Tutorial setup
If you have not done the prior sections, you’ll need to start the docker image:
docker run -it ghcr.io/spack/tutorial:isc26
and then set Spack up like this:
git clone --depth=2 --branch=releases/v1.2 https://github.com/spack/spack
. spack/share/spack/setup-env.sh
spack mirror add --unsigned tutorial /mirror
spack bootstrap now
spack compiler find
See the Basic Installation Tutorial for full details on setup.
For more help, join us in the #tutorial channel on Slack – get an invitation at slack.spack.io
Stacks Tutorial¶
Spack environments are a powerful tool not just for managing a single user’s project, but for deploying entire software stacks. In this tutorial we will see how to use them to manage large deployments, a common pattern in HPC centers.
What usually characterizes these deployments, compared to a typical single-user environment, is the need to provide the same set of packages built against a variety of configurations: different MPI libraries, LAPACK implementations, or compilers.
Below, we’ll build a representative example of such a deployment.
Our goal is to install netlib-scalapack compiled with gcc@16, which is newer than the system-provided gcc@15, and linked against:
two MPI libraries (
openmpiandmpich)two LAPACK providers (
openblasandnetlib-lapack)
We’ll also install py-scipy linked against openblas.
We’ll first focus on how to configure and install the software correctly. Then we’ll discuss how to make it accessible to users through filesystem views and module files.
Installing a Software Stack¶
Let’s start by creating an environment in a directory of our choice:
$ spack env activate --create ~/stacks
$ spack env status
==> In environment /home/spack/stacks
The first step is to install the compiler we want to use.
Let’s write a minimal spack.yaml that contains just the compiler and lmod, which we’ll need later to generate module files:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
specs:
- gcc@16 %gcc@15
- lmod@8.7.67 %gcc@15
view: false
Concretize and install:
$ spack concretize
==> Concretized 2 specs:
[b] vlwdxlj gcc@16.1.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs+profiled+strip build_system=autotools build_type=Release languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cuzgmus ^binutils@2.46.0~debuginfod+gas~gprofng~headers~interwork+ld~libiberty~lto~nls~pgo+plugins build_system=autotools compress_debug_sections=zlib libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] mmywg7x ^compiler-wrapper@1.1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] ao2onuz ^diffutils@3.12 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] vbwvgwx ^libiconv@1.18 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] z7wqeps ^gawk@5.4.0~nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] k25xiih ^readline@8.3 build_system=autotools patches:=21f0a03,72dee13,e273643 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[e] yjlog5x ^gcc@15.2.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs~profiled~strip build_system=autotools build_type=RelWithDebInfo languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3
[+] xm76mt3 ^gcc-runtime@15.2.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[e] yc4n2pp ^glibc@2.43 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] r4lhaok ^gmake@4.4.1~guile build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] xpmsy5x ^gmp@6.3.0+cxx build_system=autotools libs:=shared,static patches:=28a6673 platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] jo3eg4r ^autoconf@2.72 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] yhkgfai ^automake@1.18.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] y6uqrto ^m4@1.4.21+sigsegv build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] phcmfqk ^libsigsegv@2.15 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 3gdq456 ^libtool@2.5.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] mguwetc ^file@5.46+static build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] hhjyyqy ^xz@5.8.3~pic build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] punbqrx ^findutils@4.10.0 build_system=autotools patches:=440b954 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] gxmoxea ^mpc@1.4.1 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] melg7ga ^mpfr@4.2.2 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] sf5iutv ^autoconf-archive@2024.10.16 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] bvphs3b ^perl@5.42.0+cpanm+opcode+open+shared+threads build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 27d4iyp ^berkeley-db@18.1.40+cxx~docs+stl build_system=autotools patches:=26090f4,b231fcc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cbtgjrh ^bzip2@1.0.8~debug~pic+shared build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] cq4dkuc ^gdbm@1.26 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ohmdb2l ^less@692 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] jvlaabk ^texinfo@7.2~xs build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] sle3ix4 ^gettext@1.0+bzip2+curses+git~libunistring+libxml2+pic+shared+tar+xz build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] ujlg2ua ^libxml2@2.15.3+pic~python+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] f5xe4px ^tar@1.35 build_system=autotools zip=pigz platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] afklka7 ^pigz@2.8 build_system=makefile platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] ekvivpv ^ncurses@6.6~symlinks+termlib abi=none build_system=autotools patches:=7a351bc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] g72d7i3 ^zlib-ng@2.3.3+compat+new_strategies+opt+pic+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 63aruxk ^zstd@1.5.7+programs build_system=makefile compression:=none libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] wf22jsg lmod@8.7.67+auto_swap~redirect build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ywyq4f5 ^bc@1.08.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] litd2mh ^ed@1.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] q66mudl ^lua@5.4.8+shared build_system=makefile fetcher=curl platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] j2fa7xl ^curl@8.20.0~gssapi~ldap~libidn2~librtmp~libssh~libssh2+nghttp2 build_system=autotools libs:=shared,static tls:=openssl platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] 4lyasaz ^nghttp2@1.67.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 33yozp5 ^openssl@3.6.1~docs+shared build_system=generic certs=mozilla platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] axeuqg3 ^ca-certificates-mozilla@2026-03-19 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 4qgksuy ^unzip@6.0 build_system=makefile patches:=179330d,24582ff,251d575,3371314,44599c8,47e9def,4e5a081,59c0983,64f6498,74bc961,7d8e5c7,81ca46c,881d2ed,aced0f2,b6f64d7,b7a14c3,c9a863e,ee9e260,f6f6236,f88b9d4,fde8f9d platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] su5b2hs ^lua-luafilesystem@1.9.0 build_system=lua platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] egzwtik ^lua-luaposix@36.3 build_system=lua platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] bkzcu2s ^libxcrypt@4.5.2~obsolete_api build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] yvl6jpi ^pkgconf@2.5.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ci53fkm ^procps@4.0.6+nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] a27iqiv ^sed@4.9 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] d4ibosb ^tcl@8.6.17 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
$ spack install
[ ] d4ibosb tcl@8.6.17 fetching from build cache (0s)
[ ] 4qgksuy unzip@6.0 fetching from build cache (0s)
[ ] k25xiih readline@8.3 fetching from build cache (0s)
[ ] 4qgksuy unzip@6.0 relocating (0s)
[ ] 4lyasaz nghttp2@1.67.1 fetching from build cache (0s)
[ ] vlwdxlj gcc@16.1.0 fetching from build cache (0s)
[ ] d4ibosb tcl@8.6.17 relocating (0s)
[ ] k25xiih readline@8.3 relocating (0s)
[ ] 4lyasaz nghttp2@1.67.1 relocating (0s)
[+] 4qgksuy unzip@6.0 /home/spack/spack/opt/spack/linux-x86_64_v3/unzip-6.0-4qgksuyohalb7cfo76mqqjlmndeh3tyg (0s)
[+] k25xiih readline@8.3 /home/spack/spack/opt/spack/linux-x86_64_v3/readline-8.3-k25xiihp5dun6qwe3e5ouzdigwr5yuvz (0s)
[+] 4lyasaz nghttp2@1.67.1 /home/spack/spack/opt/spack/linux-x86_64_v3/nghttp2-1.67.1-4lyasazuklpnvidiw4ty5wvybxvkh7na (0s)
[ ] vlwdxlj gcc@16.1.0 relocating (0s)
[ ] j2fa7xl curl@8.20.0 fetching from build cache (0s)
[ ] j2fa7xl curl@8.20.0 relocating (0s)
[+] j2fa7xl curl@8.20.0 /home/spack/spack/opt/spack/linux-x86_64_v3/curl-8.20.0-j2fa7xlzdvkagqked76erodvcmcd2oqp (0s)
[ ] q66mudl lua@5.4.8 fetching from build cache (0s)
[ ] q66mudl lua@5.4.8 relocating (0s)
[+] q66mudl lua@5.4.8 /home/spack/spack/opt/spack/linux-x86_64_v3/lua-5.4.8-q66mudlsappt33u2frzcijegjay54ep3 (0s)
[ ] egzwtik lua-luaposix@36.3 fetching from build cache (0s)
[ ] su5b2hs lua-luafilesystem@1.9.0 fetching from build cache (0s)
[ ] egzwtik lua-luaposix@36.3 relocating (0s)
[ ] su5b2hs lua-luafilesystem@1.9.0 relocating (0s)
[+] su5b2hs lua-luafilesystem@1.9.0 /home/spack/spack/opt/spack/linux-x86_64_v3/lua-luafilesystem-1.9.0-su5b2hsgwgk2a4b7hkys2r23kf3me6lh (0s)
[+] egzwtik lua-luaposix@36.3 /home/spack/spack/opt/spack/linux-x86_64_v3/lua-luaposix-36.3-egzwtikjsfubsjiqpwdjemys3xqv2ytf (1s)
[+] d4ibosb tcl@8.6.17 /home/spack/spack/opt/spack/linux-x86_64_v3/tcl-8.6.17-d4ibosbgfm7536ij2dmdu6nnll5g5zpm (1s)
[ ] wf22jsg lmod@8.7.67 fetching from build cache (0s)
[ ] wf22jsg lmod@8.7.67 relocating (0s)
[+] wf22jsg lmod@8.7.67 /home/spack/spack/opt/spack/linux-x86_64_v3/lmod-8.7.67-wf22jsggn5vfsyoyuqm6ban76y7333we (0s)
[+] vlwdxlj gcc@16.1.0 /home/spack/spack/opt/spack/linux-x86_64_v3/gcc-16.1.0-vlwdxljzbis42fjrlecvyo4tmuq5eebn (1s)
Spec groups¶
We are now ready to build the software stack on top of this compiler. To do that cleanly, we’ll use spec groups, which allow you to organize specs into named collections, each with its own configuration and concretization order.
Let’s start with a single spec and a two-group spack.yaml:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
specs:
- group: compiler
specs:
- gcc@16 %gcc@15
- lmod@8.7.67 %gcc@15
- group: stack
needs: [compiler]
specs:
- netlib-scalapack %gcc@16 ^openblas ^openmpi
view: false
The environment declares two groups:
The
compilergroup contains GCC 16 andlmod(both already installed).The
stackgroup lists the software we want to deploy.
The needs: [compiler] declaration ensures that the compiler group is always concretized before the stack group, making its specs available for reuse.
Let’s concretize to see this in action:
$ spack concretize
==> Concretizing the 'compiler' group of specs
==> Concretizing the 'stack' group of specs
==> Concretized 3 specs:
[+] vlwdxlj gcc@16.1.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs+profiled+strip build_system=autotools build_type=Release languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cuzgmus ^binutils@2.46.0~debuginfod+gas~gprofng~headers~interwork+ld~libiberty~lto~nls~pgo+plugins build_system=autotools compress_debug_sections=zlib libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] mmywg7x ^compiler-wrapper@1.1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] ao2onuz ^diffutils@3.12 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] vbwvgwx ^libiconv@1.18 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] z7wqeps ^gawk@5.4.0~nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] k25xiih ^readline@8.3 build_system=autotools patches:=21f0a03,72dee13,e273643 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[e] yjlog5x ^gcc@15.2.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs~profiled~strip build_system=autotools build_type=RelWithDebInfo languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3
[+] xm76mt3 ^gcc-runtime@15.2.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[e] yc4n2pp ^glibc@2.43 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] r4lhaok ^gmake@4.4.1~guile build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] xpmsy5x ^gmp@6.3.0+cxx build_system=autotools libs:=shared,static patches:=28a6673 platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] jo3eg4r ^autoconf@2.72 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] yhkgfai ^automake@1.18.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] y6uqrto ^m4@1.4.21+sigsegv build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] phcmfqk ^libsigsegv@2.15 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 3gdq456 ^libtool@2.5.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] mguwetc ^file@5.46+static build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] hhjyyqy ^xz@5.8.3~pic build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] punbqrx ^findutils@4.10.0 build_system=autotools patches:=440b954 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] gxmoxea ^mpc@1.4.1 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] melg7ga ^mpfr@4.2.2 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] sf5iutv ^autoconf-archive@2024.10.16 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] bvphs3b ^perl@5.42.0+cpanm+opcode+open+shared+threads build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 27d4iyp ^berkeley-db@18.1.40+cxx~docs+stl build_system=autotools patches:=26090f4,b231fcc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cbtgjrh ^bzip2@1.0.8~debug~pic+shared build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] cq4dkuc ^gdbm@1.26 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ohmdb2l ^less@692 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] jvlaabk ^texinfo@7.2~xs build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] sle3ix4 ^gettext@1.0+bzip2+curses+git~libunistring+libxml2+pic+shared+tar+xz build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] ujlg2ua ^libxml2@2.15.3+pic~python+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] f5xe4px ^tar@1.35 build_system=autotools zip=pigz platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] afklka7 ^pigz@2.8 build_system=makefile platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] ekvivpv ^ncurses@6.6~symlinks+termlib abi=none build_system=autotools patches:=7a351bc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] g72d7i3 ^zlib-ng@2.3.3+compat+new_strategies+opt+pic+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 63aruxk ^zstd@1.5.7+programs build_system=makefile compression:=none libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] wf22jsg lmod@8.7.67+auto_swap~redirect build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ywyq4f5 ^bc@1.08.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] litd2mh ^ed@1.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] q66mudl ^lua@5.4.8+shared build_system=makefile fetcher=curl platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] j2fa7xl ^curl@8.20.0~gssapi~ldap~libidn2~librtmp~libssh~libssh2+nghttp2 build_system=autotools libs:=shared,static tls:=openssl platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 4lyasaz ^nghttp2@1.67.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 33yozp5 ^openssl@3.6.1~docs+shared build_system=generic certs=mozilla platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] axeuqg3 ^ca-certificates-mozilla@2026-03-19 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[+] 4qgksuy ^unzip@6.0 build_system=makefile patches:=179330d,24582ff,251d575,3371314,44599c8,47e9def,4e5a081,59c0983,64f6498,74bc961,7d8e5c7,81ca46c,881d2ed,aced0f2,b6f64d7,b7a14c3,c9a863e,ee9e260,f6f6236,f88b9d4,fde8f9d platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] su5b2hs ^lua-luafilesystem@1.9.0 build_system=lua platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] egzwtik ^lua-luaposix@36.3 build_system=lua platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] bkzcu2s ^libxcrypt@4.5.2~obsolete_api build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] yvl6jpi ^pkgconf@2.5.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ci53fkm ^procps@4.0.6+nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] a27iqiv ^sed@4.9 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] d4ibosb ^tcl@8.6.17 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] b4nkwcf netlib-scalapack@2.2.3~ipo~pic+shared build_system=cmake build_type=Release generator=make platform=linux os=ubuntu26.04 target=x86_64_v3 %c,fortran=gcc@16.1.0
[b] yonurps ^cmake@3.31.11~doc+ncurses+ownlibs~qtgui build_system=generic build_type=Release platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 6b5h3dv ^curl@8.20.0~gssapi~ldap~libidn2~librtmp~libssh~libssh2+nghttp2 build_system=autotools libs:=shared,static tls:=openssl platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] iiwpnp7 ^nghttp2@1.67.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] djpmji7 ^diffutils@3.12 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] yoq4amm ^openssl@3.6.1~docs+shared build_system=generic certs=mozilla platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] iehcspo ^ncurses@6.6~symlinks+termlib abi=none build_system=autotools patches:=7a351bc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] yd7lgm7 ^zlib-ng@2.3.3+compat+new_strategies+opt+pic+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] ghfita3 ^gcc-runtime@16.1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 6hzfsbp ^gmake@4.4.1~guile build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] kdylbqh ^openblas@0.3.33~bignuma~consistent_fpcsr+dynamic_dispatch+fortran~ilp64+locking+pic+shared~static build_system=makefile patches:=723ddc1 symbol_suffix=none threads=none platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[b] nzr6pd7 ^openmpi@5.0.10+atomics~cuda~debug+fortran~gpfs~internal-hwloc~internal-libevent~internal-pmix~ipv6~java~lustre~memchecker~openshmem~rocm~romio+rsh~static~two_level_namespace+vt+wrapper-rpath build_system=autotools fabrics:=none patches:=646eb1a romio-filesystem:=none schedulers:=none platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[b] yg7nv7p ^autoconf@2.72 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 47vgtt5 ^m4@1.4.21+sigsegv build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] r6vd65h ^libsigsegv@2.15 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] pdslnit ^automake@1.18.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] nn3ymay ^hwloc@2.13.0~cairo~cuda~gl~level_zero~libudev+libxml2~nvml~opencl+pci~rocm build_system=autotools libs:=shared,static patches:=b4db98b platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] cmgnxt6 ^libpciaccess@0.17 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cy6lybd ^util-macros@1.20.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] cxesrxa ^libxml2@2.15.3+pic~python+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] qs6av53 ^libiconv@1.18 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] bf6e7x2 ^xz@5.8.3~pic build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] m5ts755 ^libevent@2.1.12+openssl build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] raf5qk6 ^libtool@2.5.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] fc5ezqn ^file@5.46+static build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] lq6tsmz ^zstd@1.5.7+programs build_system=makefile compression:=none libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] l3if3dy ^findutils@4.10.0 build_system=autotools patches:=440b954 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] g3gt6ze ^gettext@1.0+bzip2+curses+git~libunistring+libxml2+pic+shared+tar+xz build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] tw6253j ^tar@1.35 build_system=autotools zip=pigz platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 4diropt ^pigz@2.8 build_system=makefile platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] swhw6f5 ^numactl@2.0.19 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] kjx2nfr ^openssh@10.3p1+gssapi build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] awic2yh ^krb5@1.22.2+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] yws52fh ^bison@3.8.2~color build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 4c4uuub ^libedit@3.1-20251016 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 44jhzjg ^libxcrypt@4.5.2~obsolete_api build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xxg272q ^perl@5.42.0+cpanm+opcode+open+shared+threads build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] aev2xm7 ^berkeley-db@18.1.40+cxx~docs+stl build_system=autotools patches:=26090f4,b231fcc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] ofahxlj ^bzip2@1.0.8~debug~pic+shared build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 2af63my ^gdbm@1.26 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cbnh7bw ^readline@8.3 build_system=autotools patches:=21f0a03,72dee13,e273643 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 3w5zzn3 ^less@692 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xp6fyih ^pkgconf@2.5.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] qcxnkrd ^pmix@6.1.0~munge~python build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cj2ohvh ^prrte@4.1.0 build_system=autotools patches:=64faa1a,91b28f5 schedulers:=none platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 4p7olya ^flex@2.6.3+lex~nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
Notice that the compiler group is processed first, and gcc@16 is immediately reused by the stack group.
We just used %gcc@16 to pin the compiler, but it’s a coarse constraint that must be repeated on every spec and does not distinguish between C, C++, and Fortran compilers.
Spec groups offer a better tool: the override block, which scopes any Spack configuration to a single group.
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- netlib-scalapack ^openblas ^openmpi
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
view: false
Here we used the override block to set compiler preferences at the language level, once for each group:
The
compilergroup prefersgcc@15The
stackgroup prefersgcc@16
These language preferences are expressed once and apply automatically to every spec in the group.
Tuning concretizer options¶
Now we add a second MPI variant to the stack, listing both ^openmpi and ^mpich variants of netlib-scalapack:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- netlib-scalapack ^openblas ^openmpi
- netlib-scalapack ^openblas ^mpich
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
view: false
The stack group now has two conflicting configurations, so, before concretizing, let’s check the concretizer:unify option:
$ spack config get concretizer | grep unify
unify: true
With unify: true, the concretizer restricts the environment to a single configuration of each package within its root unification set: the nodes reachable from the root specs via link or run edges.
Pure build dependencies, which fall outside the set, are not affected:
This is the right default for a single-user environment, since it ensures a filesystem view can be built without conflicts. A software stack, however, requires multiple configurations of the same package by design, so we need to relax this constraint.
Since only the stack group has conflicting configurations, we add unify: false to its override block and concretize:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- netlib-scalapack ^openblas ^openmpi
- netlib-scalapack ^openblas ^mpich
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
concretizer:
unify: false
view: false
$ spack concretize
==> Concretizing the 'compiler' group of specs
==> Concretizing the 'stack' group of specs
==> Starting concretization pool with 2 processes
==> Concretized 4 specs:
[+] vlwdxlj gcc@16.1.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs+profiled+strip build_system=autotools build_type=Release languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cuzgmus ^binutils@2.46.0~debuginfod+gas~gprofng~headers~interwork+ld~libiberty~lto~nls~pgo+plugins build_system=autotools compress_debug_sections=zlib libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] mmywg7x ^compiler-wrapper@1.1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] ao2onuz ^diffutils@3.12 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] vbwvgwx ^libiconv@1.18 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] z7wqeps ^gawk@5.4.0~nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] k25xiih ^readline@8.3 build_system=autotools patches:=21f0a03,72dee13,e273643 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[e] yjlog5x ^gcc@15.2.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs~profiled~strip build_system=autotools build_type=RelWithDebInfo languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3
[+] xm76mt3 ^gcc-runtime@15.2.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[e] yc4n2pp ^glibc@2.43 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] r4lhaok ^gmake@4.4.1~guile build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] xpmsy5x ^gmp@6.3.0+cxx build_system=autotools libs:=shared,static patches:=28a6673 platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] jo3eg4r ^autoconf@2.72 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] yhkgfai ^automake@1.18.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] y6uqrto ^m4@1.4.21+sigsegv build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] phcmfqk ^libsigsegv@2.15 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 3gdq456 ^libtool@2.5.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] mguwetc ^file@5.46+static build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] hhjyyqy ^xz@5.8.3~pic build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] punbqrx ^findutils@4.10.0 build_system=autotools patches:=440b954 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] gxmoxea ^mpc@1.4.1 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] melg7ga ^mpfr@4.2.2 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] sf5iutv ^autoconf-archive@2024.10.16 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] bvphs3b ^perl@5.42.0+cpanm+opcode+open+shared+threads build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 27d4iyp ^berkeley-db@18.1.40+cxx~docs+stl build_system=autotools patches:=26090f4,b231fcc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cbtgjrh ^bzip2@1.0.8~debug~pic+shared build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] cq4dkuc ^gdbm@1.26 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ohmdb2l ^less@692 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] jvlaabk ^texinfo@7.2~xs build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] sle3ix4 ^gettext@1.0+bzip2+curses+git~libunistring+libxml2+pic+shared+tar+xz build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] ujlg2ua ^libxml2@2.15.3+pic~python+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] f5xe4px ^tar@1.35 build_system=autotools zip=pigz platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] afklka7 ^pigz@2.8 build_system=makefile platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] ekvivpv ^ncurses@6.6~symlinks+termlib abi=none build_system=autotools patches:=7a351bc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] g72d7i3 ^zlib-ng@2.3.3+compat+new_strategies+opt+pic+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 63aruxk ^zstd@1.5.7+programs build_system=makefile compression:=none libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] wf22jsg lmod@8.7.67+auto_swap~redirect build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ywyq4f5 ^bc@1.08.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] litd2mh ^ed@1.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] q66mudl ^lua@5.4.8+shared build_system=makefile fetcher=curl platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] j2fa7xl ^curl@8.20.0~gssapi~ldap~libidn2~librtmp~libssh~libssh2+nghttp2 build_system=autotools libs:=shared,static tls:=openssl platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 4lyasaz ^nghttp2@1.67.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 33yozp5 ^openssl@3.6.1~docs+shared build_system=generic certs=mozilla platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] axeuqg3 ^ca-certificates-mozilla@2026-03-19 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[+] 4qgksuy ^unzip@6.0 build_system=makefile patches:=179330d,24582ff,251d575,3371314,44599c8,47e9def,4e5a081,59c0983,64f6498,74bc961,7d8e5c7,81ca46c,881d2ed,aced0f2,b6f64d7,b7a14c3,c9a863e,ee9e260,f6f6236,f88b9d4,fde8f9d platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] su5b2hs ^lua-luafilesystem@1.9.0 build_system=lua platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] egzwtik ^lua-luaposix@36.3 build_system=lua platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] bkzcu2s ^libxcrypt@4.5.2~obsolete_api build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] yvl6jpi ^pkgconf@2.5.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ci53fkm ^procps@4.0.6+nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] a27iqiv ^sed@4.9 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] d4ibosb ^tcl@8.6.17 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] x425zhl netlib-scalapack@2.2.3~ipo~pic+shared build_system=cmake build_type=Release generator=make platform=linux os=ubuntu26.04 target=x86_64_v3 %c,fortran=gcc@16.1.0
[b] yonurps ^cmake@3.31.11~doc+ncurses+ownlibs~qtgui build_system=generic build_type=Release platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 6b5h3dv ^curl@8.20.0~gssapi~ldap~libidn2~librtmp~libssh~libssh2+nghttp2 build_system=autotools libs:=shared,static tls:=openssl platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] iiwpnp7 ^nghttp2@1.67.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] djpmji7 ^diffutils@3.12 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] yoq4amm ^openssl@3.6.1~docs+shared build_system=generic certs=mozilla platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] iehcspo ^ncurses@6.6~symlinks+termlib abi=none build_system=autotools patches:=7a351bc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] yd7lgm7 ^zlib-ng@2.3.3+compat+new_strategies+opt+pic+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] ghfita3 ^gcc-runtime@16.1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 6hzfsbp ^gmake@4.4.1~guile build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] bovk7dt ^mpich@5.0.1~argobots~cuda+fortran+hwloc+hydra~level_zero+libxml2+pci~rocm+romio~slurm~vci~verbs+wrapperrpath~xpmem build_system=autotools datatype-engine=auto device=ch4 netmod=ofi pmi=default platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[b] l3if3dy ^findutils@4.10.0 build_system=autotools patches:=440b954 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] g3gt6ze ^gettext@1.0+bzip2+curses+git~libunistring+libxml2+pic+shared+tar+xz build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] tw6253j ^tar@1.35 build_system=autotools zip=pigz platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 4diropt ^pigz@2.8 build_system=makefile platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] nn3ymay ^hwloc@2.13.0~cairo~cuda~gl~level_zero~libudev+libxml2~nvml~opencl+pci~rocm build_system=autotools libs:=shared,static patches:=b4db98b platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] s6cemsy ^libfabric@2.5.1~asan~cuda~debug~kdreg~level_zero~lsan~rocm~tsan~ubsan~uring build_system=autotools fabrics:=sockets,tcp,udp platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cmgnxt6 ^libpciaccess@0.17 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cy6lybd ^util-macros@1.20.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] cxesrxa ^libxml2@2.15.3+pic~python+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] qs6av53 ^libiconv@1.18 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] bf6e7x2 ^xz@5.8.3~pic build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xp6fyih ^pkgconf@2.5.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] afnel7p ^python@3.14.5+bz2+ctypes+dbm~debug~freethreading+libxml2+lzma~optimizations+pic+pyexpat+pythoncmd+readline+shared+sqlite3+ssl~static~tests~tkinter+uuid+zlib+zstd build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] ofahxlj ^bzip2@1.0.8~debug~pic+shared build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xkvh6gd ^expat@2.8.1+libbsd build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] t623nqz ^libbsd@0.12.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] w3w22wx ^libmd@1.1.0 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 2af63my ^gdbm@1.26 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] jgqwv65 ^libffi@3.5.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] cbnh7bw ^readline@8.3 build_system=autotools patches:=21f0a03,72dee13,e273643 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] uliuxbf ^sqlite@3.53.1+column_metadata+fts+rtree build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] v3sdaph ^util-linux-uuid@2.41 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] lq6tsmz ^zstd@1.5.7+programs build_system=makefile compression:=none libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] kdylbqh ^openblas@0.3.33~bignuma~consistent_fpcsr+dynamic_dispatch+fortran~ilp64+locking+pic+shared~static build_system=makefile patches:=723ddc1 symbol_suffix=none threads=none platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[b] b4nkwcf netlib-scalapack@2.2.3~ipo~pic+shared build_system=cmake build_type=Release generator=make platform=linux os=ubuntu26.04 target=x86_64_v3 %c,fortran=gcc@16.1.0
[b] nzr6pd7 ^openmpi@5.0.10+atomics~cuda~debug+fortran~gpfs~internal-hwloc~internal-libevent~internal-pmix~ipv6~java~lustre~memchecker~openshmem~rocm~romio+rsh~static~two_level_namespace+vt+wrapper-rpath build_system=autotools fabrics:=none patches:=646eb1a romio-filesystem:=none schedulers:=none platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[b] yg7nv7p ^autoconf@2.72 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 47vgtt5 ^m4@1.4.21+sigsegv build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] r6vd65h ^libsigsegv@2.15 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] pdslnit ^automake@1.18.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] m5ts755 ^libevent@2.1.12+openssl build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] raf5qk6 ^libtool@2.5.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] fc5ezqn ^file@5.46+static build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] swhw6f5 ^numactl@2.0.19 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] kjx2nfr ^openssh@10.3p1+gssapi build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] awic2yh ^krb5@1.22.2+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] yws52fh ^bison@3.8.2~color build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 4c4uuub ^libedit@3.1-20251016 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 44jhzjg ^libxcrypt@4.5.2~obsolete_api build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xxg272q ^perl@5.42.0+cpanm+opcode+open+shared+threads build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] aev2xm7 ^berkeley-db@18.1.40+cxx~docs+stl build_system=autotools patches:=26090f4,b231fcc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 3w5zzn3 ^less@692 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] qcxnkrd ^pmix@6.1.0~munge~python build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cj2ohvh ^prrte@4.1.0 build_system=autotools patches:=64faa1a,91b28f5 schedulers:=none platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 4p7olya ^flex@2.6.3+lex~nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
With unify: false, Spack concretizes each root spec independently and merges the results, which is exactly what a software stack needs.
Note
If the stack is expected to have only a few duplicate nodes, when_possible is a less aggressive alternative:
override:
concretizer:
unify: when_possible
With this option Spack tries to unify the group in an eager, multi-round process.
The concretization at round n contains all the specs that could not be unified at round n-1, and considers all the specs from previous rounds for reuse.
Spec matrices¶
Let’s further expand our stack to link against different LAPACK providers as well. Adding them explicitly would be tedious, so we use a matrix to express the cross-product compactly:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- matrix:
- [netlib-scalapack]
- [^openmpi, ^mpich]
- [^openblas, ^netlib-lapack]
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
concretizer:
unify: false
view: false
A matrix expands to the cross-product of its rows. This matrix:
- matrix:
- [netlib-scalapack]
- [^openmpi, ^mpich]
- [^openblas, ^netlib-lapack]
is equivalent to this explicit list of specs:
- "netlib-scalapack ^openblas ^openmpi"
- "netlib-scalapack ^openblas ^mpich"
- "netlib-scalapack ^netlib-lapack ^openmpi"
- "netlib-scalapack ^netlib-lapack ^mpich"
No compiler annotation appears in the matrix rows: the override block in the stack group handles that.
Let’s concretize to verify our four variants:
$ spack concretize
==> Concretizing the 'stack' group of specs
==> Starting concretization pool with 2 processes
==> Concretized 2 specs:
[b] v7thz7n netlib-scalapack@2.2.3~ipo~pic+shared build_system=cmake build_type=Release generator=make platform=linux os=ubuntu26.04 target=x86_64_v3 %c,fortran=gcc@16.1.0
[b] yonurps ^cmake@3.31.11~doc+ncurses+ownlibs~qtgui build_system=generic build_type=Release platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 6b5h3dv ^curl@8.20.0~gssapi~ldap~libidn2~librtmp~libssh~libssh2+nghttp2 build_system=autotools libs:=shared,static tls:=openssl platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] iiwpnp7 ^nghttp2@1.67.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] djpmji7 ^diffutils@3.12 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] yoq4amm ^openssl@3.6.1~docs+shared build_system=generic certs=mozilla platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] axeuqg3 ^ca-certificates-mozilla@2026-03-19 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] iehcspo ^ncurses@6.6~symlinks+termlib abi=none build_system=autotools patches:=7a351bc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] yd7lgm7 ^zlib-ng@2.3.3+compat+new_strategies+opt+pic+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[+] mmywg7x ^compiler-wrapper@1.1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[+] vlwdxlj ^gcc@16.1.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs+profiled+strip build_system=autotools build_type=Release languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cuzgmus ^binutils@2.46.0~debuginfod+gas~gprofng~headers~interwork+ld~libiberty~lto~nls~pgo+plugins build_system=autotools compress_debug_sections=zlib libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] yvl6jpi ^pkgconf@2.5.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ao2onuz ^diffutils@3.12 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] vbwvgwx ^libiconv@1.18 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] z7wqeps ^gawk@5.4.0~nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] k25xiih ^readline@8.3 build_system=autotools patches:=21f0a03,72dee13,e273643 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[e] yjlog5x ^gcc@15.2.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs~profiled~strip build_system=autotools build_type=RelWithDebInfo languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3
[+] xm76mt3 ^gcc-runtime@15.2.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] r4lhaok ^gmake@4.4.1~guile build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] xpmsy5x ^gmp@6.3.0+cxx build_system=autotools libs:=shared,static patches:=28a6673 platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] jo3eg4r ^autoconf@2.72 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] yhkgfai ^automake@1.18.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] y6uqrto ^m4@1.4.21+sigsegv build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] phcmfqk ^libsigsegv@2.15 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 3gdq456 ^libtool@2.5.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] mguwetc ^file@5.46+static build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] hhjyyqy ^xz@5.8.3~pic build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] punbqrx ^findutils@4.10.0 build_system=autotools patches:=440b954 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] gxmoxea ^mpc@1.4.1 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] melg7ga ^mpfr@4.2.2 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] sf5iutv ^autoconf-archive@2024.10.16 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] bvphs3b ^perl@5.42.0+cpanm+opcode+open+shared+threads build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 27d4iyp ^berkeley-db@18.1.40+cxx~docs+stl build_system=autotools patches:=26090f4,b231fcc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cbtgjrh ^bzip2@1.0.8~debug~pic+shared build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] cq4dkuc ^gdbm@1.26 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ohmdb2l ^less@692 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] jvlaabk ^texinfo@7.2~xs build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] sle3ix4 ^gettext@1.0+bzip2+curses+git~libunistring+libxml2+pic+shared+tar+xz build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] ujlg2ua ^libxml2@2.15.3+pic~python+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] f5xe4px ^tar@1.35 build_system=autotools zip=pigz platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] afklka7 ^pigz@2.8 build_system=makefile platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] ekvivpv ^ncurses@6.6~symlinks+termlib abi=none build_system=autotools patches:=7a351bc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] g72d7i3 ^zlib-ng@2.3.3+compat+new_strategies+opt+pic+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 63aruxk ^zstd@1.5.7+programs build_system=makefile compression:=none libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] ghfita3 ^gcc-runtime@16.1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[e] yc4n2pp ^glibc@2.43 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 6hzfsbp ^gmake@4.4.1~guile build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] bovk7dt ^mpich@5.0.1~argobots~cuda+fortran+hwloc+hydra~level_zero+libxml2+pci~rocm+romio~slurm~vci~verbs+wrapperrpath~xpmem build_system=autotools datatype-engine=auto device=ch4 netmod=ofi pmi=default platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[b] l3if3dy ^findutils@4.10.0 build_system=autotools patches:=440b954 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] g3gt6ze ^gettext@1.0+bzip2+curses+git~libunistring+libxml2+pic+shared+tar+xz build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] tw6253j ^tar@1.35 build_system=autotools zip=pigz platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 4diropt ^pigz@2.8 build_system=makefile platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] nn3ymay ^hwloc@2.13.0~cairo~cuda~gl~level_zero~libudev+libxml2~nvml~opencl+pci~rocm build_system=autotools libs:=shared,static patches:=b4db98b platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] s6cemsy ^libfabric@2.5.1~asan~cuda~debug~kdreg~level_zero~lsan~rocm~tsan~ubsan~uring build_system=autotools fabrics:=sockets,tcp,udp platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cmgnxt6 ^libpciaccess@0.17 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cy6lybd ^util-macros@1.20.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] cxesrxa ^libxml2@2.15.3+pic~python+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] qs6av53 ^libiconv@1.18 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] bf6e7x2 ^xz@5.8.3~pic build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xp6fyih ^pkgconf@2.5.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] afnel7p ^python@3.14.5+bz2+ctypes+dbm~debug~freethreading+libxml2+lzma~optimizations+pic+pyexpat+pythoncmd+readline+shared+sqlite3+ssl~static~tests~tkinter+uuid+zlib+zstd build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] ofahxlj ^bzip2@1.0.8~debug~pic+shared build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xkvh6gd ^expat@2.8.1+libbsd build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] t623nqz ^libbsd@0.12.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] w3w22wx ^libmd@1.1.0 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 2af63my ^gdbm@1.26 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] jgqwv65 ^libffi@3.5.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] cbnh7bw ^readline@8.3 build_system=autotools patches:=21f0a03,72dee13,e273643 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] uliuxbf ^sqlite@3.53.1+column_metadata+fts+rtree build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] v3sdaph ^util-linux-uuid@2.41 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] lq6tsmz ^zstd@1.5.7+programs build_system=makefile compression:=none libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] zknpbz3 ^netlib-lapack@3.12.1~external-blas~ipo+lapacke+pic+shared~xblas build_system=cmake build_type=Release generator=make patches:=3059ebf,b1af8b6,e318340 platform=linux os=ubuntu26.04 target=x86_64_v3 %c,fortran=gcc@16.1.0
[b] 2zi5wtu netlib-scalapack@2.2.3~ipo~pic+shared build_system=cmake build_type=Release generator=make platform=linux os=ubuntu26.04 target=x86_64_v3 %c,fortran=gcc@16.1.0
[b] nzr6pd7 ^openmpi@5.0.10+atomics~cuda~debug+fortran~gpfs~internal-hwloc~internal-libevent~internal-pmix~ipv6~java~lustre~memchecker~openshmem~rocm~romio+rsh~static~two_level_namespace+vt+wrapper-rpath build_system=autotools fabrics:=none patches:=646eb1a romio-filesystem:=none schedulers:=none platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[b] yg7nv7p ^autoconf@2.72 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 47vgtt5 ^m4@1.4.21+sigsegv build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] r6vd65h ^libsigsegv@2.15 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] pdslnit ^automake@1.18.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] m5ts755 ^libevent@2.1.12+openssl build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] raf5qk6 ^libtool@2.5.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] fc5ezqn ^file@5.46+static build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] swhw6f5 ^numactl@2.0.19 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] kjx2nfr ^openssh@10.3p1+gssapi build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] awic2yh ^krb5@1.22.2+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] yws52fh ^bison@3.8.2~color build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 4c4uuub ^libedit@3.1-20251016 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 44jhzjg ^libxcrypt@4.5.2~obsolete_api build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xxg272q ^perl@5.42.0+cpanm+opcode+open+shared+threads build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] aev2xm7 ^berkeley-db@18.1.40+cxx~docs+stl build_system=autotools patches:=26090f4,b231fcc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 3w5zzn3 ^less@692 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] qcxnkrd ^pmix@6.1.0~munge~python build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cj2ohvh ^prrte@4.1.0 build_system=autotools patches:=64faa1a,91b28f5 schedulers:=none platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 4p7olya ^flex@2.6.3+lex~nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
We now have four variations of netlib-scalapack ready to install.
Reusable definitions¶
So far each matrix row has been written out inline.
When multiple matrices share rows, duplicating them becomes a maintenance burden.
Spack allows defining lists of constraints under the definitions attribute and reusing them across matrices.
Let’s rewrite our manifest using definitions:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
definitions:
- mpis: [openmpi, mpich]
- lapacks: [openblas, netlib-lapack]
- mpi_packages: [netlib-scalapack]
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- matrix:
- [$mpi_packages]
- [$^mpis]
- [$^lapacks]
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
concretizer:
unify: false
view: false
Concretizing confirms the result is identical:
$ spack concretize
==> No new specs to concretize.
Now that we have definitions, we can add a second matrix for serial packages that link against LAPACK but not MPI.
In a real deployment this list might include many packages, but here we use just py-scipy as an example.
Not every combination is meaningful though: py-scipy ^netlib-lapack is not a useful build, so we use exclude to drop that specific entry from the cross-product:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
definitions:
- mpis: [openmpi, mpich]
- lapacks: [openblas, netlib-lapack]
- mpi_packages: [netlib-scalapack]
- serial_packages: [py-scipy]
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- matrix:
- [$mpi_packages]
- [$^mpis]
- [$^lapacks]
- matrix:
- [$serial_packages]
- [$^lapacks]
exclude:
- "py-scipy ^netlib-lapack"
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
concretizer:
unify: false
view: false
Concretize the environment again:
$ spack concretize
==> Concretizing the 'stack' group of specs
==> Starting concretization
==> Concretized 1 spec:
[b] gouabck py-scipy@1.17.1 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[+] mmywg7x ^compiler-wrapper@1.1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[+] vlwdxlj ^gcc@16.1.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs+profiled+strip build_system=autotools build_type=Release languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cuzgmus ^binutils@2.46.0~debuginfod+gas~gprofng~headers~interwork+ld~libiberty~lto~nls~pgo+plugins build_system=autotools compress_debug_sections=zlib libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] yvl6jpi ^pkgconf@2.5.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ao2onuz ^diffutils@3.12 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] vbwvgwx ^libiconv@1.18 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] z7wqeps ^gawk@5.4.0~nls build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] k25xiih ^readline@8.3 build_system=autotools patches:=21f0a03,72dee13,e273643 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[e] yjlog5x ^gcc@15.2.0+binutils+bootstrap~graphite+libsanitizer~mold~nvptx~piclibs~profiled~strip build_system=autotools build_type=RelWithDebInfo languages:='c,c++,fortran' platform=linux os=ubuntu26.04 target=x86_64_v3
[+] xm76mt3 ^gcc-runtime@15.2.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] r4lhaok ^gmake@4.4.1~guile build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] xpmsy5x ^gmp@6.3.0+cxx build_system=autotools libs:=shared,static patches:=28a6673 platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] jo3eg4r ^autoconf@2.72 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] yhkgfai ^automake@1.18.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] y6uqrto ^m4@1.4.21+sigsegv build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] phcmfqk ^libsigsegv@2.15 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 3gdq456 ^libtool@2.5.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] mguwetc ^file@5.46+static build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] hhjyyqy ^xz@5.8.3~pic build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] punbqrx ^findutils@4.10.0 build_system=autotools patches:=440b954 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] gxmoxea ^mpc@1.4.1 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] melg7ga ^mpfr@4.2.2 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] sf5iutv ^autoconf-archive@2024.10.16 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] bvphs3b ^perl@5.42.0+cpanm+opcode+open+shared+threads build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] 27d4iyp ^berkeley-db@18.1.40+cxx~docs+stl build_system=autotools patches:=26090f4,b231fcc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] cbtgjrh ^bzip2@1.0.8~debug~pic+shared build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] cq4dkuc ^gdbm@1.26 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] ohmdb2l ^less@692 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[b] jvlaabk ^texinfo@7.2~xs build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] sle3ix4 ^gettext@1.0+bzip2+curses+git~libunistring+libxml2+pic+shared+tar+xz build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] ujlg2ua ^libxml2@2.15.3+pic~python+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] f5xe4px ^tar@1.35 build_system=autotools zip=pigz platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] afklka7 ^pigz@2.8 build_system=makefile platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@15.2.0
[+] ekvivpv ^ncurses@6.6~symlinks+termlib abi=none build_system=autotools patches:=7a351bc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] g72d7i3 ^zlib-ng@2.3.3+compat+new_strategies+opt+pic+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[+] 63aruxk ^zstd@1.5.7+programs build_system=makefile compression:=none libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@15.2.0
[b] ghfita3 ^gcc-runtime@16.1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[e] yc4n2pp ^glibc@2.43 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 6mel4bl ^meson@1.11.1 build_system=python_pip patches:=0f0b1bd platform=linux os=ubuntu26.04 target=x86_64_v3
[b] yqhdh2x ^ninja@1.13.2+re2c build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] rcco4zy ^re2c@4.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] ytwnkqf ^py-setuptools@82.0.1 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] kdylbqh ^openblas@0.3.33~bignuma~consistent_fpcsr+dynamic_dispatch+fortran~ilp64+locking+pic+shared~static build_system=makefile patches:=723ddc1 symbol_suffix=none threads=none platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[b] 6hzfsbp ^gmake@4.4.1~guile build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xp6fyih ^pkgconf@2.5.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 3ggpdjv ^py-cython@3.2.4 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] c6oww3b ^py-meson-python@0.19.0 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] x55wsqe ^py-packaging@26.2 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] hn6pbjh ^py-flit-core@3.12.0 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] cuihsxt ^py-pyproject-metadata@0.11.0 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 7g2cva3 ^py-numpy@2.4.6 build_system=python_pip patches:=873745d platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 5p3frq3 ^py-pip@26.1 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 3iqsk4i ^py-pybind11@3.0.2+ipo build_system=cmake build_type=Release generator=ninja platform=linux os=ubuntu26.04 target=x86_64_v3 %cxx=gcc@16.1.0
[b] yonurps ^cmake@3.31.11~doc+ncurses+ownlibs~qtgui build_system=generic build_type=Release platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 6b5h3dv ^curl@8.20.0~gssapi~ldap~libidn2~librtmp~libssh~libssh2+nghttp2 build_system=autotools libs:=shared,static tls:=openssl platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] iiwpnp7 ^nghttp2@1.67.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 5anzcvk ^py-scikit-build-core@0.12.2~pyproject build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx,fortran=gcc@16.1.0
[b] 4qnonii ^py-hatch-vcs@0.5.0 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] psffea6 ^py-setuptools-scm@9.2.2+toml build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] loixb6c ^git@2.53.0+man+nls+perl+subtree~tcltk build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] yg7nv7p ^autoconf@2.72 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3
[b] pdslnit ^automake@1.18.1 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 6hwe4tz ^libidn2@2.3.8 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] iyz34h3 ^libunistring@1.4.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] raf5qk6 ^libtool@2.5.4 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] fc5ezqn ^file@5.46+static build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] l3if3dy ^findutils@4.10.0 build_system=autotools patches:=440b954 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 47vgtt5 ^m4@1.4.21+sigsegv build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] r6vd65h ^libsigsegv@2.15 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] kjx2nfr ^openssh@10.3p1+gssapi build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] awic2yh ^krb5@1.22.2+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] yws52fh ^bison@3.8.2~color build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 4c4uuub ^libedit@3.1-20251016 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 44jhzjg ^libxcrypt@4.5.2~obsolete_api build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] wttcr2f ^pcre2@10.44~jit+multibyte+pic build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] dxgdks3 ^py-hatchling@1.29.0 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] etdouzz ^py-pluggy@1.6.0 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] cj7d3wo ^py-trove-classifiers@2026.6.1.19 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] t7ufmfz ^py-calver@2025.10.20 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] ble4v64 ^py-pathspec@1.1.1 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 36lyfl6 ^py-pythran@0.18.1 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3 %cxx=gcc@16.1.0
[b] k7zfexy ^py-beniget@0.4.2.post1 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] 5nakdbl ^py-gast@0.6.0 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] kbtru35 ^py-ply@3.11 build_system=python_pip platform=linux os=ubuntu26.04 target=x86_64_v3
[b] yygojb3 ^py-wheel@0.45.1 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] afnel7p ^python@3.14.5+bz2+ctypes+dbm~debug~freethreading+libxml2+lzma~optimizations+pic+pyexpat+pythoncmd+readline+shared+sqlite3+ssl~static~tests~tkinter+uuid+zlib+zstd build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] ofahxlj ^bzip2@1.0.8~debug~pic+shared build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] djpmji7 ^diffutils@3.12 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] xkvh6gd ^expat@2.8.1+libbsd build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] t623nqz ^libbsd@0.12.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] w3w22wx ^libmd@1.1.0 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 2af63my ^gdbm@1.26 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] g3gt6ze ^gettext@1.0+bzip2+curses+git~libunistring+libxml2+pic+shared+tar+xz build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] qs6av53 ^libiconv@1.18 build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cxesrxa ^libxml2@2.15.3+pic~python+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] tw6253j ^tar@1.35 build_system=autotools zip=pigz platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] 4diropt ^pigz@2.8 build_system=makefile platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] jgqwv65 ^libffi@3.5.2 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] iehcspo ^ncurses@6.6~symlinks+termlib abi=none build_system=autotools patches:=7a351bc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] yoq4amm ^openssl@3.6.1~docs+shared build_system=generic certs=mozilla platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] axeuqg3 ^ca-certificates-mozilla@2026-03-19 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
[b] xxg272q ^perl@5.42.0+cpanm+opcode+open+shared+threads build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] aev2xm7 ^berkeley-db@18.1.40+cxx~docs+stl build_system=autotools patches:=26090f4,b231fcc platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] 3w5zzn3 ^less@692 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] cbnh7bw ^readline@8.3 build_system=autotools patches:=21f0a03,72dee13,e273643 platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] uliuxbf ^sqlite@3.53.1+column_metadata+fts+rtree build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] v3sdaph ^util-linux-uuid@2.41 build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] bf6e7x2 ^xz@5.8.3~pic build_system=autotools libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c=gcc@16.1.0
[b] yd7lgm7 ^zlib-ng@2.3.3+compat+new_strategies+opt+pic+shared build_system=autotools platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] lq6tsmz ^zstd@1.5.7+programs build_system=makefile compression:=none libs:=shared,static platform=linux os=ubuntu26.04 target=x86_64_v3 %c,cxx=gcc@16.1.0
[b] bcclnnz ^python-venv@1.0 build_system=generic platform=linux os=ubuntu26.04 target=x86_64_v3
The exclusion worked: the environment contains only py-scipy ^openblas.
Conditional definitions¶
A common need in multi-site or multi-cluster deployments is enabling different software sets based on environment variables or host properties.
Definitions support a when clause for exactly this.
when is a Python expression evaluated at concretization time, with access to the following variables:
variable name |
value |
|---|---|
|
The spack platform name for this machine |
|
The default spack os name and version string for this machine |
|
The default spack target string for this machine |
|
The default spack architecture string platform-os-target for this machine |
|
Alias for |
|
A dictionary representing the user’s environment variables |
|
The python |
|
The hostname of this node |
Suppose we want to build with mpich by default, and add openmpi when a site-specific environment variable is set.
We can express this with two definitions of mpis, the second guarded by a when clause:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
definitions:
- mpis: [mpich]
- mpis: [openmpi]
when: 'env.get("SPACK_STACK_USE_OPENMPI", "") == "1"'
- lapacks: [openblas, netlib-lapack]
- mpi_packages: [netlib-scalapack]
- serial_packages: [py-scipy]
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- matrix:
- [$mpi_packages]
- [$^mpis]
- [$^lapacks]
- matrix:
- [$serial_packages]
- [$^lapacks]
exclude:
- "py-scipy ^netlib-lapack"
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
concretizer:
unify: false
view: false
When multiple definitions share the same name, they are concatenated, so the conditional entry simply appends openmpi to the list when the variable is set.
First, concretize without the variable:
$ spack concretize
==> No new specs to concretize.
$ spack find -cl netlib-scalapack
==> In environment /home/spack/stacks (5 root specs)
-- root specs / compiler ----------------------------------------
[+] vlwdxlj gcc@16 [+] wf22jsg lmod@8.7.67
-- root specs / stack -------------------------------------------
[b] v7thz7n netlib-scalapack [b] x425zhl netlib-scalapack [b] gouabck py-scipy
-- linux-ubuntu26.04-x86_64_v3 / %c,fortran=gcc@16.1.0 ----------
[b] v7thz7n netlib-scalapack@2.2.3 [b] x425zhl netlib-scalapack@2.2.3
==> 0 installed packages
==> 2 concretized packages to be installed
Only mpich is used.
Now set the variable and re-concretize:
$ export SPACK_STACK_USE_OPENMPI=1
$ spack concretize
$ spack find -cl netlib-scalapack
==> In environment /home/spack/stacks (7 root specs)
-- root specs / compiler ----------------------------------------
[+] vlwdxlj gcc@16 [+] wf22jsg lmod@8.7.67
-- root specs / stack -------------------------------------------
[b] v7thz7n netlib-scalapack [b] 2zi5wtu netlib-scalapack [b] gouabck py-scipy
[b] x425zhl netlib-scalapack [b] b4nkwcf netlib-scalapack
-- linux-ubuntu26.04-x86_64_v3 / %c,fortran=gcc@16.1.0 ----------
[b] v7thz7n netlib-scalapack@2.2.3 [b] 2zi5wtu netlib-scalapack@2.2.3
[b] x425zhl netlib-scalapack@2.2.3 [b] b4nkwcf netlib-scalapack@2.2.3
==> 0 installed packages
==> 4 concretized packages to be installed
Both MPI providers are now active.
We now have a complete, well-structured environment. It’s time to install it:
$ spack install
[ ] ghfita3 gcc-runtime@16.1.0 fetching from build cache (0s)
[ ] ghfita3 gcc-runtime@16.1.0 relocating (0s)
[+] ghfita3 gcc-runtime@16.1.0 /home/spack/spack/opt/spack/linux-x86_64_v3/gcc-runtime-16.1.0-ghfita36diqcbps7me6eh5im5crijl3g (0s)
[ ] ofahxlj bzip2@1.0.8 fetching from build cache (0s)
[ ] ofahxlj bzip2@1.0.8 relocating (0s)
[ ] kdylbqh openblas@0.3.33 fetching from build cache (0s)
[ ] kdylbqh openblas@0.3.33 relocating (0s)
[ ] 44jhzjg libxcrypt@4.5.2 fetching from build cache (0s)
[ ] 44jhzjg libxcrypt@4.5.2 relocating (0s)
[ ] qs6av53 libiconv@1.18 fetching from build cache (0s)
[ ] qs6av53 libiconv@1.18 relocating (0s)
[ ] cmgnxt6 libpciaccess@0.17 fetching from build cache (0s)
[ ] cmgnxt6 libpciaccess@0.17 relocating (0s)
[ ] zknpbz3 netlib-lapack@3.12.1 fetching from build cache (0s)
[ ] zknpbz3 netlib-lapack@3.12.1 relocating (0s)
[ ] swhw6f5 numactl@2.0.19 fetching from build cache (0s)
[ ] swhw6f5 numactl@2.0.19 relocating (0s)
[ ] jgqwv65 libffi@3.5.2 fetching from build cache (0s)
[ ] jgqwv65 libffi@3.5.2 relocating (0s)
[ ] yd7lgm7 zlib-ng@2.3.3 fetching from build cache (0s)
[ ] yd7lgm7 zlib-ng@2.3.3 relocating (0s)
[ ] bf6e7x2 xz@5.8.3 fetching from build cache (0s)
[ ] bf6e7x2 xz@5.8.3 relocating (0s)
[ ] w3w22wx libmd@1.1.0 fetching from build cache (0s)
[ ] w3w22wx libmd@1.1.0 relocating (0s)
[ ] v3sdaph util-linux-uuid@2.41 fetching from build cache (0s)
[+] ofahxlj bzip2@1.0.8 /home/spack/spack/opt/spack/linux-x86_64_v3/bzip2-1.0.8-ofahxljg6r4dtlyfgtolxexpmnw4cnkz (0s)
[+] 44jhzjg libxcrypt@4.5.2 /home/spack/spack/opt/spack/linux-x86_64_v3/libxcrypt-4.5.2-44jhzjg42xausczvpn26wr6gyzsh2wnu (0s)
[ ] iehcspo ncurses@6.6 fetching from build cache (0s)
[+] cmgnxt6 libpciaccess@0.17 /home/spack/spack/opt/spack/linux-x86_64_v3/libpciaccess-0.17-cmgnxt6kpobrrgj7k5a4iweh6p2qemnw (0s)
[ ] lq6tsmz zstd@1.5.7 fetching from build cache (0s)
[ ] v3sdaph util-linux-uuid@2.41 relocating (0s)
[+] swhw6f5 numactl@2.0.19 /home/spack/spack/opt/spack/linux-x86_64_v3/numactl-2.0.19-swhw6f5gno25h4ap4h6htedy5thh2k55 (0s)
[+] qs6av53 libiconv@1.18 /home/spack/spack/opt/spack/linux-x86_64_v3/libiconv-1.18-qs6av53jc6wvykpse3q7o7sm2dazibpv (0s)
[ ] s6cemsy libfabric@2.5.1 fetching from build cache (0s)
[ ] iehcspo ncurses@6.6 relocating (0s)
[+] jgqwv65 libffi@3.5.2 /home/spack/spack/opt/spack/linux-x86_64_v3/libffi-3.5.2-jgqwv653kext2ew4mzjg3cbmlflyhdbb (0s)
[ ] lq6tsmz zstd@1.5.7 relocating (0s)
[ ] s6cemsy libfabric@2.5.1 relocating (0s)
[+] yd7lgm7 zlib-ng@2.3.3 /home/spack/spack/opt/spack/linux-x86_64_v3/zlib-ng-2.3.3-yd7lgm73h2wqb74e6pz2sdszwkubvpzd (0s)
[+] w3w22wx libmd@1.1.0 /home/spack/spack/opt/spack/linux-x86_64_v3/libmd-1.1.0-w3w22wxnstajwmg2wmtfm6nayugxqbvo (0s)
[ ] yoq4amm openssl@3.6.1 fetching from build cache (0s)
[+] bf6e7x2 xz@5.8.3 /home/spack/spack/opt/spack/linux-x86_64_v3/xz-5.8.3-bf6e7x2te7rdq6kt43maxjnnntvnkpza (0s)
[ ] 4diropt pigz@2.8 fetching from build cache (0s)
[+] lq6tsmz zstd@1.5.7 /home/spack/spack/opt/spack/linux-x86_64_v3/zstd-1.5.7-lq6tsmzmnrljkb52otacw2o4iqmskxn5 (0s)
[ ] t623nqz libbsd@0.12.2 fetching from build cache (0s)
[+] v3sdaph util-linux-uuid@2.41 /home/spack/spack/opt/spack/linux-x86_64_v3/util-linux-uuid-2.41-v3sdaph4k3onzfo5nbhk6gt3typaycl7 (0s)
[ ] yoq4amm openssl@3.6.1 relocating (0s)
[ ] 4diropt pigz@2.8 relocating (0s)
[+] zknpbz3 netlib-lapack@3.12.1 /home/spack/spack/opt/spack/linux-x86_64_v3/netlib-lapack-3.12.1-zknpbz3xor7rz2jo6ek5p4dba6ac4ujs (0s)
[ ] t623nqz libbsd@0.12.2 relocating (0s)
[ ] cxesrxa libxml2@2.15.3 fetching from build cache (0s)
[+] s6cemsy libfabric@2.5.1 /home/spack/spack/opt/spack/linux-x86_64_v3/libfabric-2.5.1-s6cemsy3l7cfqnetr3sjcrtcsln4quey (0s)
[ ] cxesrxa libxml2@2.15.3 relocating (0s)
[+] 4diropt pigz@2.8 /home/spack/spack/opt/spack/linux-x86_64_v3/pigz-2.8-4diroptd5kjfnmxyjlgutr4sh7m53ctf (0s)
[+] kdylbqh openblas@0.3.33 /home/spack/spack/opt/spack/linux-x86_64_v3/openblas-0.3.33-kdylbqhaa64fb44w6hbaoj4eibakcc6u (0s)
[ ] tw6253j tar@1.35 fetching from build cache (0s)
[+] t623nqz libbsd@0.12.2 /home/spack/spack/opt/spack/linux-x86_64_v3/libbsd-0.12.2-t623nqzi6s364pdvgvf7ooygtsagc7ue (0s)
[ ] tw6253j tar@1.35 relocating (0s)
[+] cxesrxa libxml2@2.15.3 /home/spack/spack/opt/spack/linux-x86_64_v3/libxml2-2.15.3-cxesrxalf2jcma3g5dew6ovwxyqqgdqn (0s)
[+] yoq4amm openssl@3.6.1 /home/spack/spack/opt/spack/linux-x86_64_v3/openssl-3.6.1-yoq4ammrtbfxojt6fms67bekd7a5izst (0s)
[ ] xkvh6gd expat@2.8.1 fetching from build cache (0s)
[ ] xkvh6gd expat@2.8.1 relocating (0s)
[ ] m5ts755 libevent@2.1.12 fetching from build cache (0s)
[+] tw6253j tar@1.35 /home/spack/spack/opt/spack/linux-x86_64_v3/tar-1.35-tw6253j6xqn7udhufev2afnhjepbunqh (0s)
[ ] m5ts755 libevent@2.1.12 relocating (0s)
[+] xkvh6gd expat@2.8.1 /home/spack/spack/opt/spack/linux-x86_64_v3/expat-2.8.1-xkvh6gdnqgwccukuhsyvfry63qseotlz (0s)
[+] iehcspo ncurses@6.6 /home/spack/spack/opt/spack/linux-x86_64_v3/ncurses-6.6-iehcspoirzcldubv7budljlbeiooqvpa (0s)
[ ] 4c4uuub libedit@3.1-20251016 fetching from build cache (0s)
[+] m5ts755 libevent@2.1.12 /home/spack/spack/opt/spack/linux-x86_64_v3/libevent-2.1.12-m5ts755lehs4a7r5psjeh5k6pjptap4v (0s)
[ ] g3gt6ze gettext@1.0 fetching from build cache (0s)
[ ] 4c4uuub libedit@3.1-20251016 relocating (0s)
[ ] cbnh7bw readline@8.3 fetching from build cache (0s)
[ ] nn3ymay hwloc@2.13.0 fetching from build cache (1s)
[ ] cbnh7bw readline@8.3 relocating (1s)
[ ] g3gt6ze gettext@1.0 relocating (1s)
[ ] nn3ymay hwloc@2.13.0 relocating (1s)
[+] 4c4uuub libedit@3.1-20251016 /home/spack/spack/opt/spack/linux-x86_64_v3/libedit-3.1-20251016-4c4uuubtih3trasplcywhk2ena3knzjk (1s)
[+] cbnh7bw readline@8.3 /home/spack/spack/opt/spack/linux-x86_64_v3/readline-8.3-cbnh7bwdfvbzqpoww77ltp2s54nizaxx (1s)
[ ] uliuxbf sqlite@3.53.1 fetching from build cache (0s)
[ ] 2af63my gdbm@1.26 fetching from build cache (0s)
[ ] uliuxbf sqlite@3.53.1 relocating (0s)
[ ] 2af63my gdbm@1.26 relocating (0s)
[+] nn3ymay hwloc@2.13.0 /home/spack/spack/opt/spack/linux-x86_64_v3/hwloc-2.13.0-nn3ymaytmizysjb5hfbyzn7migudvklf (1s)
[ ] bovk7dt mpich@5.0.1 fetching from build cache (0s)
[ ] qcxnkrd pmix@6.1.0 fetching from build cache (0s)
[+] 2af63my gdbm@1.26 /home/spack/spack/opt/spack/linux-x86_64_v3/gdbm-1.26-2af63myyx6xsgd5vuwqhj7ibwmnptibj (0s)
[ ] bovk7dt mpich@5.0.1 relocating (0s)
[ ] qcxnkrd pmix@6.1.0 relocating (0s)
[+] uliuxbf sqlite@3.53.1 /home/spack/spack/opt/spack/linux-x86_64_v3/sqlite-3.53.1-uliuxbfvj27y6podjxir7af7frdjuord (0s)
[+] qcxnkrd pmix@6.1.0 /home/spack/spack/opt/spack/linux-x86_64_v3/pmix-6.1.0-qcxnkrd6rle6hjxvjeevshakgvxxsi7g (0s)
[+] g3gt6ze gettext@1.0 /home/spack/spack/opt/spack/linux-x86_64_v3/gettext-1.0-g3gt6ze7gojves2utbt43mddfmx3evv3 (1s)
[ ] cj2ohvh prrte@4.1.0 fetching from build cache (0s)
[ ] awic2yh krb5@1.22.2 fetching from build cache (0s)
[ ] cj2ohvh prrte@4.1.0 relocating (0s)
[ ] afnel7p python@3.14.5 fetching from build cache (0s)
[ ] awic2yh krb5@1.22.2 relocating (0s)
[ ] afnel7p python@3.14.5 relocating (0s)
[+] awic2yh krb5@1.22.2 /home/spack/spack/opt/spack/linux-x86_64_v3/krb5-1.22.2-awic2yh3c7mlbqbamsoxcwrciv4h6utb (0s)
[+] cj2ohvh prrte@4.1.0 /home/spack/spack/opt/spack/linux-x86_64_v3/prrte-4.1.0-cj2ohvhvhiawcijsrkgs5nldcxi42hfd (0s)
[ ] kjx2nfr openssh@10.3p1 fetching from build cache (0s)
[ ] kjx2nfr openssh@10.3p1 relocating (0s)
[+] kjx2nfr openssh@10.3p1 /home/spack/spack/opt/spack/linux-x86_64_v3/openssh-10.3p1-kjx2nfrhrvxzutcvg3zyxjv7tvyqiat2 (0s)
[ ] nzr6pd7 openmpi@5.0.10 fetching from build cache (0s)
[+] bovk7dt mpich@5.0.1 /home/spack/spack/opt/spack/linux-x86_64_v3/mpich-5.0.1-bovk7dtifzhj3qyej4pmqssvi4oda2k4 (0s)
[ ] nzr6pd7 openmpi@5.0.10 relocating (0s)
[ ] x425zhl netlib-scalapack@2.2.3 fetching from build cache (0s)
[ ] v7thz7n netlib-scalapack@2.2.3 fetching from build cache (0s)
[ ] x425zhl netlib-scalapack@2.2.3 relocating (0s)
[ ] v7thz7n netlib-scalapack@2.2.3 relocating (0s)
[+] x425zhl netlib-scalapack@2.2.3 /home/spack/spack/opt/spack/linux-x86_64_v3/netlib-scalapack-2.2.3-x425zhlxzxtbvtol4voqnfnwkwi7i7jm (1s)
[+] v7thz7n netlib-scalapack@2.2.3 /home/spack/spack/opt/spack/linux-x86_64_v3/netlib-scalapack-2.2.3-v7thz7nq3c2kfw4rbqhsulbd3yprhrap (1s)
[+] afnel7p python@3.14.5 /home/spack/spack/opt/spack/linux-x86_64_v3/python-3.14.5-afnel7povb4oermf4jcb5pchgjqkmmux (1s)
[ ] bcclnnz python-venv@1.0 fetching from build cache (0s)
[+] nzr6pd7 openmpi@5.0.10 /home/spack/spack/opt/spack/linux-x86_64_v3/openmpi-5.0.10-nzr6pd7wjjwsa7eltwui6dzmv7klrucn (1s)
[ ] bcclnnz python-venv@1.0 relocating (0s)
[ ] b4nkwcf netlib-scalapack@2.2.3 fetching from build cache (0s)
[ ] 2zi5wtu netlib-scalapack@2.2.3 fetching from build cache (0s)
[ ] b4nkwcf netlib-scalapack@2.2.3 relocating (0s)
[ ] 2zi5wtu netlib-scalapack@2.2.3 relocating (0s)
[+] bcclnnz python-venv@1.0 /home/spack/spack/opt/spack/linux-x86_64_v3/python-venv-1.0-bcclnnzhc3vordjcpw474p7acng2prlx (0s)
[ ] 7g2cva3 py-numpy@2.4.6 fetching from build cache (0s)
[ ] 3iqsk4i py-pybind11@3.0.2 fetching from build cache (0s)
[ ] 7g2cva3 py-numpy@2.4.6 relocating (0s)
[ ] 3iqsk4i py-pybind11@3.0.2 relocating (0s)
[+] b4nkwcf netlib-scalapack@2.2.3 /home/spack/spack/opt/spack/linux-x86_64_v3/netlib-scalapack-2.2.3-b4nkwcfstoe3im2ia3x4sybstfpwfprz (0s)
[+] 2zi5wtu netlib-scalapack@2.2.3 /home/spack/spack/opt/spack/linux-x86_64_v3/netlib-scalapack-2.2.3-2zi5wtuh2jnzfsfjctcvwu7bxugildzo (0s)
[+] 3iqsk4i py-pybind11@3.0.2 /home/spack/spack/opt/spack/linux-x86_64_v3/py-pybind11-3.0.2-3iqsk4i75azrkcftvwmnyp6hezl35dl3 (0s)
[+] 7g2cva3 py-numpy@2.4.6 /home/spack/spack/opt/spack/linux-x86_64_v3/py-numpy-2.4.6-7g2cva3wwgq2nffqpvwujvc2rbbk57hp (0s)
[ ] gouabck py-scipy@1.17.1 fetching from build cache (0s)
[ ] gouabck py-scipy@1.17.1 relocating (0s)
[+] gouabck py-scipy@1.17.1 /home/spack/spack/opt/spack/linux-x86_64_v3/py-scipy-1.17.1-gouabckeot5bo6tkkjiz5o5grjhbhptd (1s)
Other useful features¶
Before moving to views and modules, two other features are worth knowing about.
The first is source mirrors. When the environment is active, creating one is as simple as:
$ spack mirror create --all -d ./stacks-mirror
This fetches all the tarballs listed in spack.lock into the given directory.
You can then move the mirror to an air-gapped machine and register it with:
$ spack mirror add <name> <stacks-mirror>
This lets you rebuild the specs from source on the target machine. Alternatively, to create a buildcache you can:
$ spack gpg create <name> <e-mail>
$ spack buildcache push ./mirror
Don’t forget to set an appropriate value for the padding of the install tree; see how to set up relocation in our documentation.
Multiple Filesystem Views¶
Views give users access to the installed software through standard filesystem paths, without requiring them to interact with Spack directly. A stack, however, contains multiple configurations of the same package, which would conflict in a single merged directory tree. Instead, we define multiple views, each covering a curated subset of the stack, with optional projections that control the directory layout.
Let’s add view descriptors to our spack.yaml:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
definitions:
- mpis: [mpich]
- mpis: [openmpi]
when: 'env.get("SPACK_STACK_USE_OPENMPI", "") == "1"'
- lapacks: [openblas, netlib-lapack]
- mpi_packages: [netlib-scalapack]
- serial_packages: [py-scipy]
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- matrix:
- [$mpi_packages]
- [$^mpis]
- [$^lapacks]
- matrix:
- [$serial_packages]
- [$^lapacks]
exclude:
- "py-scipy ^netlib-lapack"
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
concretizer:
unify: false
view:
default:
root: views/default
select: ['%gcc@16']
exclude: [^mpich, ^netlib-lapack]
full:
root: views/full
projections:
^mpi^lapack: '{name}/{name}-{version}-{^c.name}-{^c.version}-{^mpi.name}-{^mpi.version}-{^lapack.name}-{^lapack.version}'
^lapack: '{name}/{name}-{version}-{^c.name}-{^c.version}-{^lapack.name}-{^lapack.version}'
'%c': '{name}/{name}-{version}-{^c.name}-{^c.version}'
'%cxx': '{name}/{name}-{version}-{^cxx.name}-{^cxx.version}'
'%fortran': '{name}/{name}-{version}-{^fortran.name}-{^fortran.version}'
all: '{name}/{name}-{version}'
We defined two views, default and full.
The default view consists of all the packages compiled with gcc@16, excluding those that depend on mpich or netlib-lapack.
View descriptors accept both select and exclude constraints.
The full view uses a more complex projection to place each spec into an appropriate subdirectory, according to the first constraint that matches.
all is the default projection and always has the lowest priority, regardless of the order in which it appears.
To avoid confusion, we advise always keeping it last in projections.
Concretize to regenerate the views and check their structure:
$ spack concretize
==> No new specs to concretize.
==> Updating view at /home/spack/stacks/views/default
==> Updating view at /home/spack/stacks/views/full
$ ls ~/stacks/views/default
bin etc include lib lib64 libexec man pyvenv.cfg sbin share var
$ ls ~/stacks/views/default/lib
cmake libevent_core-2.1.so.7.0.1 libgettextpo.a libkrb5.so libmpich.so libpanel.so libtinfo_g.a
gettext libevent_core.a libgettextpo.so libkrb5.so.3 libmpichcxx.so libpanel.so.6 libtinfow.a
krb5 libevent_core.so libgettextpo.so.0 libkrb5.so.3.3 libmpichf90.so libpanel.so.6.6 libtinfow.so
libasan.so.8 libevent_extra-2.1.so.7 libgettextpo.so.0.6.0 libkrb5support.so libmpicxx.a libpanel_g.a libtinfow.so.6
libasprintf.a libevent_extra-2.1.so.7.0.1 libgettextsrc-1.0.so libkrb5support.so.0 libmpicxx.so libpanelw.a libtinfow.so.6.6
libasprintf.so libevent_extra.a libgettextsrc.a libkrb5support.so.0.1 libmpicxx.so.12 libpanelw.so libtinfow_g.a
libasprintf.so.0 libevent_extra.so libgettextsrc.so liblapack.so libmpicxx.so.12.6.1 libpanelw.so.6 libtmglib.so
libasprintf.so.0.0.0 libevent_openssl-2.1.so.7 libgfortran.so.5 liblapack.so.3 libmpifort.a libpanelw.so.6.6 libtmglib.so.3
libatomic.so.1 libevent_openssl-2.1.so.7.0.1 libgomp.so.1 liblapack.so.3.12.0 libmpifort.so libpanelw_g.a libtmglib.so.3.12.0
libblas.so libevent_openssl.a libgssapi_krb5.so liblapacke.so libmpifort.so.12 libpciaccess.a libtsan.so.2
libblas.so.3 libevent_openssl.so libgssapi_krb5.so.2 liblapacke.so.3 libmpifort.so.12.6.1 libpciaccess.so libubsan.so.1
libblas.so.3.12.0 libevent_pthreads-2.1.so.7 libgssapi_krb5.so.2.2 liblapacke.so.3.12.0 libmpl.so libpciaccess.so.0 libuuid.a
libbsd-ctor.a libevent_pthreads-2.1.so.7.0.1 libgssrpc.so liblsan.so.0 libncurses++.a libpciaccess.so.0.11.1 libuuid.so
libbsd.a libevent_pthreads.a libgssrpc.so.4 liblzma.a libncurses++.so libpmix.a libuuid.so.1
libbsd.so libevent_pthreads.so libgssrpc.so.4.2 liblzma.so libncurses++.so.6 libpmix.so libuuid.so.1.3.0
libbsd.so.0 libexpat.a libhistory.a liblzma.so.5 libncurses++.so.6.6 libpmix.so.2 libverto.so
libbsd.so.0.12.2 libexpat.so libhistory.so liblzma.so.5.8.3 libncurses++_g.a libpmix.so.2.23.0 libverto.so.0
libbz2.a libexpat.so.1 libhistory.so.8 libmd.a libncurses++w.a libprrte.a libverto.so.0.0
libbz2.so libexpat.so.1.12.1 libhistory.so.8.3 libmd.so libncurses++w.so libprrte.so libxml2.so
libbz2.so.1 libfabric.a libhwasan.so.0 libmd.so.0 libncurses++w.so.6 libprrte.so.3 libxml2.so.16
libbz2.so.1.0 libfabric.so libhwloc.a libmd.so.0.1.0 libncurses++w.so.6.6 libprrte.so.3.1.0 libxml2.so.16.1.3
libbz2.so.1.0.8 libfabric.so.1 libhwloc.so libmenu.a libncurses++w_g.a libpython3.14.so libz.a
libcblas.so libfabric.so.1.31.1 libhwloc.so.15 libmenu.so libncurses.a libpython3.14.so.1.0 libz.so
libcblas.so.3 libfmpich.so libhwloc.so.15.10.2 libmenu.so.6 libncurses.so libpython3.so libz.so.1
libcblas.so.3.12.0 libform.a libiconv.a libmenu.so.6.6 libncurses.so.6 libquadmath.so.0 libz.so.1.3.1.zlib-ng
libcharset.a libform.so libiconv.so libmenu_g.a libncurses.so.6.6 libreadline.a libzstd.a
libcharset.so libform.so.6 libiconv.so.2 libmenuw.a libncurses_g.a libreadline.so libzstd.so
libcharset.so.1 libform.so.6.6 libiconv.so.2.7.0 libmenuw.so libncursesw.a libreadline.so.8 libzstd.so.1
libcharset.so.1.0.0 libform_g.a libitm.so.1 libmenuw.so.6 libncursesw.so libreadline.so.8.3 libzstd.so.1.5.7
libcom_err.so libformw.a libk5crypto.so libmenuw.so.6.6 libncursesw.so.6 libscalapack.so mpi.mod
libcom_err.so.3 libformw.so libk5crypto.so.3 libmenuw_g.a libncursesw.so.6.6 libscalapack.so.2.2 mpi_ext.mod
libcom_err.so.3.0 libformw.so.6 libk5crypto.so.3.1 libmpi.a libncursesw_g.a libscalapack.so.2.2.3 mpi_f08.mod
libcrypt.a libformw.so.6.6 libkadm5clnt.so libmpi.so libnuma.a libsqlite3.a mpi_f08_callbacks.mod
libcrypt.so libformw_g.a libkadm5clnt_mit.so libmpi.so.12 libnuma.so libsqlite3.so mpi_f08_ext.mod
libcrypt.so.2 libgcc_s.so.1 libkadm5clnt_mit.so.12 libmpi.so.12.6.1 libnuma.so.1 libsqlite3.so.0 mpi_f08_interfaces.mod
libcrypt.so.2.0.0 libgdbm.a libkadm5clnt_mit.so.12.0 libmpi.so.40 libnuma.so.1.0.0 libsqlite3.so.3.53.1 mpi_f08_interfaces_callbacks.mod
libcurses.so libgdbm.so libkadm5srv.so libmpi.so.40.40.7 libopa.so libssp.so.0 mpi_f08_types.mod
libedit.a libgdbm.so.6 libkadm5srv_mit.so libmpi_mpifh.so libopen-pal.so libstdc++.so.6 mpi_types.mod
libedit.so libgdbm.so.6.0.0 libkadm5srv_mit.so.12 libmpi_mpifh.so.40 libopen-pal.so.80 libtextstyle.a openmpi
libedit.so.0 libgdbm_compat.a libkadm5srv_mit.so.12.0 libmpi_mpifh.so.40.40.1 libopen-pal.so.80.0.5 libtextstyle.so pkgconfig
libedit.so.0.0.76 libgdbm_compat.so libkdb5.so libmpi_usempi_ignore_tkr.so libopenblas-r0.3.33.a libtextstyle.so.0 pmpi_f08_interfaces.mod
libevent-2.1.so.7 libgdbm_compat.so.4 libkdb5.so.10 libmpi_usempi_ignore_tkr.so.40 libopenblas-r0.3.33.so libtextstyle.so.0.2.7 preloadable_libintl.so
libevent-2.1.so.7.0.1 libgdbm_compat.so.4.0.0 libkdb5.so.10.0 libmpi_usempi_ignore_tkr.so.40.40.1 libopenblas.a libtinfo.a python3.14
libevent.a libgettextlib-1.0.so libkrad.so libmpi_usempif08.so libopenblas.so libtinfo.so terminfo
libevent.so libgettextlib.a libkrad.so.0 libmpi_usempif08.so.40 libopenblas.so.0 libtinfo.so.6
libevent_core-2.1.so.7 libgettextlib.so libkrad.so.0.0 libmpi_usempif08.so.40.40.3 libpanel.a libtinfo.so.6.6
$ ls ~/stacks/views/full
binutils expat gdbm hwloc libedit libffi libpciaccess lmod mpfr netlib-lapack numactl openssh pmix readline tcl xz
bzip2 gcc gettext krb5 libevent libiconv libxcrypt lua mpich netlib-scalapack openblas openssl prrte sqlite unzip zlib-ng
curl gcc-runtime gmp libbsd libfabric libmd libxml2 mpc ncurses nghttp2 openmpi pigz python tar util-linux-uuid zstd
$ ls ~/stacks/views/full/gcc/
gcc-16.1.0-gcc-15.2.0
$ ls ~/stacks/views/full/gcc/gcc-16.1.0-gcc-15.2.0
bin include lib lib64 libexec share
By default, a view includes all packages, link and run dependencies included.
Setting link: roots restricts it to root specs only:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
definitions:
- mpis: [mpich]
- mpis: [openmpi]
when: 'env.get("SPACK_STACK_USE_OPENMPI", "") == "1"'
- lapacks: [openblas, netlib-lapack]
- mpi_packages: [netlib-scalapack]
- serial_packages: [py-scipy]
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- matrix:
- [$mpi_packages]
- [$^mpis]
- [$^lapacks]
- matrix:
- [$serial_packages]
- [$^lapacks]
exclude:
- "py-scipy ^netlib-lapack"
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
concretizer:
unify: false
view:
default:
root: views/default
select: ['%gcc@16']
exclude: [^mpich, ^netlib-lapack]
link: roots
full:
root: views/full
projections:
^mpi^lapack: '{name}/{name}-{version}-{^c.name}-{^c.version}-{^mpi.name}-{^mpi.version}-{^lapack.name}-{^lapack.version}'
^lapack: '{name}/{name}-{version}-{^c.name}-{^c.version}-{^lapack.name}-{^lapack.version}'
'%c': '{name}/{name}-{version}-{^c.name}-{^c.version}'
'%cxx': '{name}/{name}-{version}-{^cxx.name}-{^cxx.version}'
'%fortran': '{name}/{name}-{version}-{^fortran.name}-{^fortran.version}'
all: '{name}/{name}-{version}'
$ spack concretize
==> No new specs to concretize.
==> Updating view at /home/spack/stacks/views/default
$ ls ~/stacks/views/default
lib
$ ls ~/stacks/views/default/lib
cmake libscalapack.so libscalapack.so.2.2 libscalapack.so.2.2.3 pkgconfig python3.14
$ ls ~/stacks/views/full
binutils expat gdbm hwloc libedit libffi libpciaccess lmod mpfr netlib-lapack numactl openssh pmix readline tcl xz
bzip2 gcc gettext krb5 libevent libiconv libxcrypt lua mpich netlib-scalapack openblas openssl prrte sqlite unzip zlib-ng
curl gcc-runtime gmp libbsd libfabric libmd libxml2 mpc ncurses nghttp2 openmpi pigz python tar util-linux-uuid zstd
Now we see only the root packages in the default view. The rest are hidden, but are still available in the full view. Full documentation on views is available in the Spack environments guide.
Module Files¶
Module files are the standard mechanism for managing multiple software versions on HPC systems.
In this section we’ll show how to configure and generate a hierarchical module structure with lmod.
Note
A more in-depth tutorial, focused only on module files, can be found at Module Files Tutorial.
It covers the general architecture and differences between environment-modules and lmod that are out of scope here.
Since lmod is already part of our compiler group and has been installed, we just need to add the module command to our shell:
$ . $(spack location -i lmod)/lmod/lmod/init/bash
You should now have the module command available:
$ module --version
Modules based on Lua: Version 8.7.67 2025-10-04 20:16 -05:00
by Robert McLay mclay@tacc.utexas.edu
The next step is to add some basic configuration to our spack.yaml to generate module files:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
definitions:
- mpis: [mpich]
- mpis: [openmpi]
when: 'env.get("SPACK_STACK_USE_OPENMPI", "") == "1"'
- lapacks: [openblas, netlib-lapack]
- mpi_packages: [netlib-scalapack]
- serial_packages: [py-scipy]
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- matrix:
- [$mpi_packages]
- [$^mpis]
- [$^lapacks]
- matrix:
- [$serial_packages]
- [$^lapacks]
exclude:
- "py-scipy ^netlib-lapack"
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
concretizer:
unify: false
view: false
modules:
default:
enable:
- lmod
roots:
lmod: modules
lmod:
hierarchy:
- mpi
- lapack
core_specs:
- '%gcc@15'
This configuration tells Spack to:
generate
lmodmodule files undermodules/, with a hierarchy based onmpiandlapackplace all specs built with the system compiler (
%gcc@15) into theCoredesignation
We can generate the module files and use them with the following commands:
$ spack module lmod refresh -y
$ module use $PWD/stacks/modules/linux-ubuntu26.04-x86_64/Core
Let’s check the generated module files:
$ module av
----------------------------------------------------------------------- /home/spack/stacks/modules/linux-ubuntu26.04-x86_64/Core -----------------------------------------------------------------------
binutils/2.46.0-cuzgmus gcc/15.2.0-yjlog5x libxcrypt/4.5.2-bkzcu2s mpc/1.4.1-gxmoxea pkgconf/2.5.1-yvl6jpi zlib-ng/2.3.3-g72d7i3
bzip2/1.0.8-cbtgjrh gcc/16.1.0-vlwdxlj (D) libxml2/2.15.3-ujlg2ua mpfr/4.2.2-melg7ga readline/8.3-k25xiih zstd/1.5.7-63aruxk
compiler-wrapper/1.1.0-mmywg7x gettext/1.0-sle3ix4 lmod/8.7.67-wf22jsg ncurses/6.6-ekvivpv tar/1.35-f5xe4px
curl/8.20.0-j2fa7xl glibc/2.43-yc4n2pp lua-luafilesystem/1.9.0-su5b2hs nghttp2/1.67.1-4lyasaz tcl/8.6.17-d4ibosb
gcc-runtime/15.2.0-xm76mt3 gmp/6.3.0-xpmsy5x lua-luaposix/36.3-egzwtik openssl/3.6.1-33yozp5 unzip/6.0-4qgksuy
gcc-runtime/16.1.0-ghfita3 (D) libiconv/1.18-vbwvgwx lua/5.4.8-q66mudl pigz/2.8-afklka7 xz/5.8.3-hhjyyqy
Where:
D: Default Module
If the avail list is too long consider trying:
"module --default avail" or "ml -d av" to just list the default modules.
"module overview" or "ml ov" to display the number of modules for each name.
Use "module spider" to find all possible modules and extensions.
Use "module keyword key1 key2 ..." to search for all possible modules matching any of the "keys".
The set of modules is already usable, and the hierarchy already works.
For instance, we can load the gcc compiler and check that gcc is in our path and that many modules are available, all compiled with gcc@16:
$ module load gcc
$ which gcc
/home/spack/spack/opt/spack/linux-x86_64_v3/gcc-16.1.0-vlwdxljzbis42fjrlecvyo4tmuq5eebn/bin/gcc
$ gcc --version
gcc (Spack GCC) 16.1.0
Copyright (C) 2026 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ module av
-------------------------------------------------------------------- /home/spack/stacks/modules/linux-ubuntu26.04-x86_64/gcc/16.1.0 --------------------------------------------------------------------
bzip2/1.0.8-ofahxlj (D) libedit/3.1-20251016-4c4uuub libxcrypt/4.5.2-44jhzjg (D) openmpi/5.0.10-nzr6pd7 python-venv/1.0-bcclnnz zlib-ng/2.3.3-yd7lgm7 (D)
expat/2.8.1-xkvh6gd libevent/2.1.12-m5ts755 libxml2/2.15.3-cxesrxa openssh/10.3p1-kjx2nfr python/3.14.5-afnel7p zstd/1.5.7-lq6tsmz
gdbm/1.26-2af63my libfabric/2.5.1-s6cemsy mpich/5.0.1-bovk7dt openssl/3.6.1-yoq4amm readline/8.3-cbnh7bw
gettext/1.0-g3gt6ze libffi/3.5.2-jgqwv65 ncurses/6.6-iehcspo (D) pigz/2.8-4diropt (D) sqlite/3.53.1-uliuxbf
hwloc/2.13.0-nn3ymay libiconv/1.18-qs6av53 netlib-lapack/3.12.1-zknpbz3 pmix/6.1.0-qcxnkrd tar/1.35-tw6253j (D)
krb5/1.22.2-awic2yh libmd/1.1.0-w3w22wx numactl/2.0.19-swhw6f5 prrte/4.1.0-cj2ohvh util-linux-uuid/2.41-v3sdaph
libbsd/0.12.2-t623nqz libpciaccess/0.17-cmgnxt6 openblas/0.3.33-kdylbqh py-pybind11/3.0.2-3iqsk4i xz/5.8.3-bf6e7x2
----------------------------------------------------------------------- /home/spack/stacks/modules/linux-ubuntu26.04-x86_64/Core -----------------------------------------------------------------------
binutils/2.46.0-cuzgmus (L) gcc/15.2.0-yjlog5x libxcrypt/4.5.2-bkzcu2s mpc/1.4.1-gxmoxea (L) pkgconf/2.5.1-yvl6jpi zlib-ng/2.3.3-g72d7i3 (L)
bzip2/1.0.8-cbtgjrh gcc/16.1.0-vlwdxlj (L,D) libxml2/2.15.3-ujlg2ua (D) mpfr/4.2.2-melg7ga (L) readline/8.3-k25xiih (D) zstd/1.5.7-63aruxk (L,D)
compiler-wrapper/1.1.0-mmywg7x gettext/1.0-sle3ix4 (D) lmod/8.7.67-wf22jsg ncurses/6.6-ekvivpv tar/1.35-f5xe4px
curl/8.20.0-j2fa7xl glibc/2.43-yc4n2pp (L) lua-luafilesystem/1.9.0-su5b2hs nghttp2/1.67.1-4lyasaz tcl/8.6.17-d4ibosb
gcc-runtime/15.2.0-xm76mt3 (L) gmp/6.3.0-xpmsy5x (L) lua-luaposix/36.3-egzwtik openssl/3.6.1-33yozp5 (D) unzip/6.0-4qgksuy
gcc-runtime/16.1.0-ghfita3 (D) libiconv/1.18-vbwvgwx (D) lua/5.4.8-q66mudl pigz/2.8-afklka7 xz/5.8.3-hhjyyqy (D)
Where:
D: Default Module
L: Module is loaded
If the avail list is too long consider trying:
"module --default avail" or "ml -d av" to just list the default modules.
"module overview" or "ml ov" to display the number of modules for each name.
Use "module spider" to find all possible modules and extensions.
Use "module keyword key1 key2 ..." to search for all possible modules matching any of the "keys".
$ module unload gcc
The default configuration has a few rough edges, though:
dependency modules from
gccclutter the listing with packages users will never load directlyhashes in module names make scripts non-portable across similar environments
some modules may need custom environment variables specific to site policy
To address all these needs, we can extend our modules configuration:
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
definitions:
- mpis: [mpich]
- mpis: [openmpi]
when: 'env.get("SPACK_STACK_USE_OPENMPI", "") == "1"'
- lapacks: [openblas, netlib-lapack]
- mpi_packages: [netlib-scalapack]
- serial_packages: [py-scipy]
specs:
- group: compiler
specs:
- gcc@16
- lmod@8.7.67
override:
packages:
c:
prefer: [gcc@15]
cxx:
prefer: [gcc@15]
fortran:
prefer: [gcc@15]
- group: stack
needs: [compiler]
specs:
- matrix:
- [$mpi_packages]
- [$^mpis]
- [$^lapacks]
- matrix:
- [$serial_packages]
- [$^lapacks]
exclude:
- "py-scipy ^netlib-lapack"
override:
packages:
c:
prefer: [gcc@16]
cxx:
prefer: [gcc@16]
fortran:
prefer: [gcc@16]
concretizer:
unify: false
view: false
modules:
default:
enable:
- lmod
roots:
lmod: modules
lmod:
hierarchy:
- mpi
- lapack
core_specs:
- '%gcc@15'
hash_length: 0
include:
- gcc
exclude:
- '%gcc@15'
- autoconf
all:
environment:
set:
'{name}_ROOT': '{prefix}'
openmpi:
environment:
set:
SLURM_MPI_TYPE: pmi2
OMPI_MCA_btl_openib_warn_default_gid_prefix: '0'
projections:
all: '{name}/{version}'
Regenerate the modules:
$ spack module lmod refresh --delete-tree -y
==> Regenerating lmod module files
Now we have module files without hashes, a correct hierarchy, and our custom environment variables:
$ module load gcc
$ module load openmpi openblas netlib-scalapack py-scipy
$ module av
-------------------------------------------------------------------- /home/spack/stacks/modules/linux-ubuntu26.04-x86_64/gcc/16.1.0 --------------------------------------------------------------------
bzip2/1.0.8 hwloc/2.13.0 libevent/2.1.12 libmd/1.1.0 mpich/5.0.1 openblas/0.3.33 pigz/2.8 python-venv/1.0 tar/1.35 zstd/1.5.7
expat/2.8.1 krb5/1.22.2 libfabric/2.5.1 libpciaccess/0.17 ncurses/6.6 openmpi/5.0.10 pmix/6.1.0 python/3.14.5 util-linux-uuid/2.41
gdbm/1.26 libbsd/0.12.2 libffi/3.5.2 libxcrypt/4.5.2 netlib-lapack/3.12.1 openssh/10.3p1 prrte/4.1.0 readline/8.3 xz/5.8.3
gettext/1.0 libedit/3.1-20251016 libiconv/1.18 libxml2/2.15.3 numactl/2.0.19 openssl/3.6.1 py-pybind11/3.0.2 sqlite/3.53.1 zlib-ng/2.3.3
----------------------------------------------------------------------- /home/spack/stacks/modules/linux-ubuntu26.04-x86_64/Core -----------------------------------------------------------------------
compiler-wrapper/1.1.0 gcc-runtime/16.1.0 gcc/15.2.0 gcc/16.1.0 (L,D) glibc/2.43 (L)
Where:
D: Default Module
L: Module is loaded
If the avail list is too long consider trying:
"module --default avail" or "ml -d av" to just list the default modules.
"module overview" or "ml ov" to display the number of modules for each name.
Use "module spider" to find all possible modules and extensions.
Use "module keyword key1 key2 ..." to search for all possible modules matching any of the "keys".
$ module load mpich
Lmod is automatically replacing "openmpi/5.0.10" with "mpich/5.0.1".
Due to MODULEPATH changes, the following have been reloaded:
1) netlib-scalapack/2.2.3
$ module load netlib-lapack
Lmod is automatically replacing "openblas/0.3.33" with "netlib-lapack/3.12.1".
Due to MODULEPATH changes, the following have been reloaded:
1) netlib-scalapack/2.2.3
$ module purge
This concludes the stacks tutorial.
Summary¶
In this tutorial we built a realistic HPC software stack: a cross-product of MPI and LAPACK libraries, compiled with a newer compiler than the system default. Along the way we used:
Spec groups with
needsandoverrideto control build order and compiler selection per groupSpec matrices and definitions to express the cross-product concisely
Conditional definitions to make the MPI selection configurable at concretization time
Filesystem views and module files to make the software accessible to users