Environments, spack.yaml, and spack.lock

We’ve shown you how to install and remove packages with Spack. You can use spack install to install packages, spack uninstall to remove them, and spack find to look at and query what is installed. We’ve also shown you how to customize Spack’s installation with configuration files like packages.yaml.

If you build a lot of software, or if you work on multiple projects, managing everything in one place can be overwhelming. The default spack find output may contain many packages, but you may want to just focus on packages a particular project. Moreover, you may want to include special configuration with your package groups, e.g., to build all the packages in the same group the same way.

Spack environments provide a way to handle these problems.

Environment basics

Let’s look at the output of spack find at this point in the tutorial.

$ bin/spack find
==> 70 installed packages
-- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
tcl@8.6.8  zlib@1.2.8  zlib@1.2.11

-- linux-ubuntu16.04-x86_64 / gcc@4.7 ---------------------------
zlib@1.2.11

-- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
adept-utils@1.0.1  hdf5@1.10.4          mpc@1.1.0               perl@5.26.2
autoconf@2.69      hdf5@1.10.4          mpfr@3.1.6              pkgconf@1.4.2
automake@1.16.1    hdf5@1.10.4          mpich@3.2.1             readline@7.0
boost@1.68.0       hwloc@1.11.9         mpileaks@1.0            suite-sparse@5.3.0
bzip2@1.0.6        hypre@2.15.1         mumps@5.1.1             tar@1.30
callpath@1.0.4     hypre@2.15.1         mumps@5.1.1             tcl@8.6.8
cmake@3.12.3       isl@0.18             ncurses@6.1             tcl@8.6.8
diffutils@3.6      libdwarf@20180129    netcdf@4.6.1            texinfo@6.5
dyninst@9.3.2      libiberty@2.31.1     netcdf@4.6.1            trilinos@12.12.1
elfutils@0.173     libpciaccess@0.13.5  netlib-scalapack@2.0.2  trilinos@12.12.1
findutils@4.6.0    libsigsegv@2.11      netlib-scalapack@2.0.2  util-macros@1.19.1
gcc@7.2.0          libtool@2.4.6        numactl@2.0.11          xz@5.2.4
gdbm@1.14.1        libxml2@2.9.8        openblas@0.3.3          zlib@1.2.8
gettext@0.19.8.1   m4@1.4.18            openmpi@3.1.3           zlib@1.2.8
glm@0.9.7.1        matio@1.5.9          openssl@1.0.2o          zlib@1.2.11
gmp@6.1.2          matio@1.5.9          parmetis@4.0.3
hdf5@1.10.4        metis@5.1.0          parmetis@4.0.3

This is a complete, but cluttered view. There are packages built with both openmpi and mpich, as well as multiple variants of other packages, like zlib. The query mechanism we learned about in spack find can help, but it would be nice if we could start from a clean slate without losing what we’ve already done.

Creating and activating environments

The spack env command can help. Let’s create a new environment:

$ spack env create myproject
==> Created environment 'myproject' in ~/spack/var/spack/environments/myproject

An environment is a virtualized spack instance that you can use for a specific purpose. You can see the environments we’ve created so far like this:

$ spack env list
==> 1 environments
    myproject

And you can activate an environment with spack env activate:

$ spack env activate myproject

Once you enter an environment, spack find shows only what is in the current environment. That’s nothing, so far:

$ spack find
==> In environment myproject
==> No root specs

==> 0 installed packages

The spack find output is still slightly different. It tells you that you’re in the myproject environment, so that you don’t panic when you see that there is nothing installed. It also says that there are no root specs. We’ll get back to what that means later.

If you only want to check what environment you are in, you can use spack env status:

$ spack env status
==> In environment myproject

And, if you want to leave this environment and go back to normal Spack, you can use spack env deactivate. We like to use the despacktivate alias (which Spack sets up automatically) for short:

$ despacktivate     # short alias for `spack env deactivate`
$ spack env status
==> No active environment
$ spack find
netcdf@4.6.1            readline@7.0        zlib@1.2.11
diffutils@3.6      hdf5@1.10.4       m4@1.4.18            netcdf@4.6.1            suite-sparse@5.3.0
dyninst@10.0.0     hwloc@1.11.9      matio@1.5.9          netlib-scalapack@2.0.2  tar@1.30
elfutils@0.173     hypre@2.15.1      matio@1.5.9          netlib-scalapack@2.0.2  tcl@8.6.8
findutils@4.6.0    hypre@2.15.1      metis@5.1.0          numactl@2.0.11          tcl@8.6.8
gcc@7.2.0          intel-tbb@2019    mpc@1.1.0            openblas@0.3.3          texinfo@6.5~

Installing packages

Ok, now that we understand how creation and activation work, let’s go back to myproject and install a few packages:

$ spack env activate myproject
$ spack install tcl
==> tcl is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/tcl-8.6.8-qhwyccywhx2i6s7ob2gvjrjtj3rnfuqt
$ spack install trilinos
==> trilinos is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/trilinos-12.12.1-rlsruavxqvwk2tgxzxboclbo6ykjf54r
$ spack find
==> In environment myproject
==> Root specs
tcl  trilinos

==> 22 installed packages
-- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
boost@1.68.0  hwloc@1.11.9         matio@1.5.9   netlib-scalapack@2.0.2  parmetis@4.0.3      xz@5.2.4
bzip2@1.0.6   hypre@2.15.1         metis@5.1.0   numactl@2.0.11          suite-sparse@5.3.0  zlib@1.2.11
glm@0.9.7.1   libpciaccess@0.13.5  mumps@5.1.1   openblas@0.3.3          tcl@8.6.8
hdf5@1.10.4   libxml2@2.9.8        netcdf@4.6.1  openmpi@3.1.3           trilinos@12.12.1

We’ve installed tcl and trilinos in our environment, along with all of their dependencies. We call tcl and trilinos the roots because we asked for them explicitly. The other 20 packages listed under “installed packages” are present because they were needed as dependencies. So, these are the roots of the packages’ dependency graph.

The “<package> is already installed” messages above are generated because we already installed these packages in previous steps of the tutorial, and we don’t have to rebuild them to put them in an environment.

Now let’s create another project. We’ll call this one myproject2:

$ spack env create myproject2
==> Created environment 'myproject2' in ~/spack/var/spack/environments/myproject2
$ spack env activate myproject2
$ spack install hdf5
==> hdf5 is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.4-ozyvmhzdew66byarohm4p36ep7wtcuiw
$ spack install trilinos
==> trilinos is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/trilinos-12.12.1-rlsruavxqvwk2tgxzxboclbo6ykjf54r
$ spack find
==> In environment myproject2
==> Root specs
hdf5  trilinos

==> 22 installed packages
-- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
boost@1.68.0  hdf5@1.10.4          libxml2@2.9.8  netcdf@4.6.1            openmpi@3.1.3       xz@5.2.4
bzip2@1.0.6   hwloc@1.11.9         matio@1.5.9    netlib-scalapack@2.0.2  parmetis@4.0.3      zlib@1.2.11
glm@0.9.7.1   hypre@2.15.1         metis@5.1.0    numactl@2.0.11          suite-sparse@5.3.0
hdf5@1.10.4   libpciaccess@0.13.5  mumps@5.1.1    openblas@0.3.3          trilinos@12.12.1

Now we have two environments: one with tcl and trilinos, and another with hdf5 and trilinos.

We can uninstall trilinos from myproject2 as you would expect:

$ spack uninstall trilinos
==> The following packages will be uninstalled:

    -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
    rlsruav trilinos@12.12.1%gcc~alloptpkgs+amesos+amesos2+anasazi+aztec+belos+boost build_type=RelWithDebInfo ~cgns~complex~dtk+epetra+epetraext+exodus+explicit_template_instantiation~float+fortran~fortrilinos+gtest+hdf5+hypre+ifpack+ifpack2~intrepid~intrepid2~isorropia+kokkos+metis~minitensor+ml+muelu+mumps~nox~openmp~phalanx~piro~pnetcdf~python~rol~rythmos+sacado~shards+shared~stk+suite-sparse~superlu~superlu-dist~teko~tempus+teuchos+tpetra~x11~xsdkflags~zlib+zoltan+zoltan2
==> Do you want to proceed? [y/N] y
$ spack find
==> In environment myproject2
==> Root specs
hdf5

==> 8 installed packages
-- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
hdf5@1.10.4   libpciaccess@0.13.5  numactl@2.0.11  xz@5.2.4
hwloc@1.11.9  libxml2@2.9.8        openmpi@3.1.3   zlib@1.2.11

Now there is only one root spec, hdf5, which requires fewer additional dependencies.

However, we still needed trilinos for the myproject environment! What happened to it? Let’s switch back and see.

$ despacktivate
$ spack env activate myproject
$ spack find
==> In environment myproject
==> Root specs
tcl  trilinos

==> 22 installed packages
-- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
boost@1.68.0  hwloc@1.11.9         matio@1.5.9   netlib-scalapack@2.0.2  parmetis@4.0.3      xz@5.2.4
bzip2@1.0.6   hypre@2.15.1         metis@5.1.0   numactl@2.0.11          suite-sparse@5.3.0  zlib@1.2.11
glm@0.9.7.1   libpciaccess@0.13.5  mumps@5.1.1   openblas@0.3.3          tcl@8.6.8
hdf5@1.10.4   libxml2@2.9.8        netcdf@4.6.1  openmpi@3.1.3           trilinos@12.12.1

Spack is smart enough to realize that trilinos is still present in the other environment. Trilinos won’t actually be uninstalled unless it is no longer needed by any environments or packages. If it is still needed, it is only removed from the environment.

Dealing with many specs at once

In the above examples, we just used install and uninstall. There are other ways to deal with groups of packages, as well.

Adding specs

Let’s go back to our first myproject environment and add a few specs instead of installing them:

$ spack add hdf5
==> Adding hdf5 to environment myproject
$ spack add gmp
==> Adding mumps to environment myproject
$ spack find
==> In environment myproject
==> Root specs
gmp  hdf5  tcl  trilinos

==> 22 installed packages
-- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
boost@1.68.0  hwloc@1.11.9         matio@1.5.9   netlib-scalapack@2.0.2  parmetis@4.0.3      xz@5.2.4
bzip2@1.0.6   hypre@2.15.1         metis@5.1.0   numactl@2.0.11          suite-sparse@5.3.0  zlib@1.2.11
glm@0.9.7.1   libpciaccess@0.13.5  mumps@5.1.1   openblas@0.3.3          tcl@8.6.8
hdf5@1.10.4   libxml2@2.9.8        netcdf@4.6.1  openmpi@3.1.3           trilinos@12.12.1

Let’s take a close look at what happened. The two packages we added, hdf5 and gmp, are present, but they’re not installed in the environment yet. spack add just adds roots to the environment, but it does not automatically install them.

We can install all the as-yet uninstalled packages in an environment by simply running spack install with no arguments:

$ spack install
==> Concretizing hdf5
[+]  ozyvmhz  hdf5@1.10.4%gcc@5.4.0~cxx~debug~fortran~hl+mpi+pic+shared~szip~threadsafe arch=linux-ubuntu16.04-x86_64
[+]  3njc4q5      ^openmpi@3.1.3%gcc@5.4.0~cuda+cxx_exceptions fabrics= ~java~legacylaunchers~memchecker~pmi schedulers= ~sqlite3~thread_multiple+vt arch=linux-ubuntu16.04-x86_64
[+]  43tkw5m          ^hwloc@1.11.9%gcc@5.4.0~cairo~cuda+libxml2+pci+shared arch=linux-ubuntu16.04-x86_64
[+]  5urc6tc              ^libpciaccess@0.13.5%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  o2pfwjf                  ^libtool@2.4.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  suf5jtc                      ^m4@1.4.18%gcc@5.4.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=linux-ubuntu16.04-x86_64
[+]  fypapcp                          ^libsigsegv@2.11%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  fovrh7a                  ^pkgconf@1.4.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  milz7fm                  ^util-macros@1.19.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  wpexsph              ^libxml2@2.9.8%gcc@5.4.0~python arch=linux-ubuntu16.04-x86_64
[+]  teneqii                  ^xz@5.2.4%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  5nus6kn                  ^zlib@1.2.11%gcc@5.4.0+optimize+pic+shared arch=linux-ubuntu16.04-x86_64
[+]  ft463od              ^numactl@2.0.11%gcc@5.4.0 patches=592f30f7f5f757dfc239ad0ffd39a9a048487ad803c26b419e0f96b8cda08c1a arch=linux-ubuntu16.04-x86_64
[+]  3sx2gxe                  ^autoconf@2.69%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  ic2kyoa                      ^perl@5.26.2%gcc@5.4.0+cpanm patches=0eac10ed90aeb0459ad8851f88081d439a4e41978e586ec743069e8b059370ac +shared+threads arch=linux-ubuntu16.04-x86_64
[+]  q4fpyuo                          ^gdbm@1.14.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  nxhwrg7                              ^readline@7.0%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  3o765ou                                  ^ncurses@6.1%gcc@5.4.0~symlinks~termlib arch=linux-ubuntu16.04-x86_64
[+]  rymw7im                  ^automake@1.16.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
==> Concretizing gmp
[+]  qc4qcfz  gmp@6.1.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  3sx2gxe      ^autoconf@2.69%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  suf5jtc          ^m4@1.4.18%gcc@5.4.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=linux-ubuntu16.04-x86_64
[+]  fypapcp              ^libsigsegv@2.11%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  ic2kyoa          ^perl@5.26.2%gcc@5.4.0+cpanm patches=0eac10ed90aeb0459ad8851f88081d439a4e41978e586ec743069e8b059370ac +shared+threads arch=linux-ubuntu16.04-x86_64
[+]  q4fpyuo              ^gdbm@1.14.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  nxhwrg7                  ^readline@7.0%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  3o765ou                      ^ncurses@6.1%gcc@5.4.0~symlinks~termlib arch=linux-ubuntu16.04-x86_64
[+]  fovrh7a                          ^pkgconf@1.4.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  rymw7im      ^automake@1.16.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  o2pfwjf      ^libtool@2.4.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
==> Installing environment myproject
==> tcl is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/tcl-8.6.8-qhwyccywhx2i6s7ob2gvjrjtj3rnfuqt
==> trilinos is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/trilinos-12.12.1-rlsruavxqvwk2tgxzxboclbo6ykjf54r
==> hdf5 is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.4-ozyvmhzdew66byarohm4p36ep7wtcuiw
==> gmp is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/gmp-6.1.2-qc4qcfz4monpllc3nqupdo7vwinf73sw

Spack will concretize the new roots, and install everything you added to the environment. Now we can see the installed roots in the output of spack find:

$ spack find
==> In environment myproject
==> Root specs
gmp  hdf5  tcl  trilinos

==> 24 installed packages
-- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
boost@1.68.0  hdf5@1.10.4   libpciaccess@0.13.5  mumps@5.1.1             openblas@0.3.3      tcl@8.6.8
bzip2@1.0.6   hdf5@1.10.4   libxml2@2.9.8        netcdf@4.6.1            openmpi@3.1.3       trilinos@12.12.1
glm@0.9.7.1   hwloc@1.11.9  matio@1.5.9          netlib-scalapack@2.0.2  parmetis@4.0.3      xz@5.2.4
gmp@6.1.2     hypre@2.15.1  metis@5.1.0          numactl@2.0.11          suite-sparse@5.3.0  zlib@1.2.11

We can build whole environments this way, by adding specs and installing all at once, or we can install them with the usual install and uninstall portions. The advantage to doing them all at once is that we don’t have to write a script outside of Spack to automate this, and we can kick off a large build of many packages easily.

Configuration

So far, myproject does not have any special configuration associated with it. The specs concretize using Spack’s defaults:

$ spack spec hypre
Input spec
--------------------------------
hypre

Concretized
--------------------------------
hypre@2.15.1%gcc@5.4.0~debug~int64+internal-superlu+mpi+shared arch=linux-ubuntu16.04-x86_64
    ^openblas@0.3.3%gcc@5.4.0 cpu_target= ~ilp64 patches=47cfa7a952ac7b2e4632c73ae199d69fb54490627b66a62c681e21019c4ddc9d,714aea33692304a50bd0ccde42590c176c82ded4a8ac7f06e573dc8071929c33 +pic+shared threads=none ~virtual_machine arch=linux-ubuntu16.04-x86_64
    ^openmpi@3.1.3%gcc@5.4.0~cuda+cxx_exceptions fabrics= ~java~legacylaunchers~memchecker~pmi schedulers= ~sqlite3~thread_multiple+vt arch=linux-ubuntu16.04-x86_64
        ^hwloc@1.11.9%gcc@5.4.0~cairo~cuda+libxml2+pci+shared arch=linux-ubuntu16.04-x86_64
            ^libpciaccess@0.13.5%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                ^libtool@2.4.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                    ^m4@1.4.18%gcc@5.4.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=linux-ubuntu16.04-x86_64
                        ^libsigsegv@2.11%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                ^pkgconf@1.4.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                ^util-macros@1.19.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
            ^libxml2@2.9.8%gcc@5.4.0~python arch=linux-ubuntu16.04-x86_64
                ^xz@5.2.4%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                ^zlib@1.2.11%gcc@5.4.0+optimize+pic+shared arch=linux-ubuntu16.04-x86_64
            ^numactl@2.0.11%gcc@5.4.0 patches=592f30f7f5f757dfc239ad0ffd39a9a048487ad803c26b419e0f96b8cda08c1a arch=linux-ubuntu16.04-x86_64
                ^autoconf@2.69%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                    ^perl@5.26.2%gcc@5.4.0+cpanm patches=0eac10ed90aeb0459ad8851f88081d439a4e41978e586ec743069e8b059370ac +shared+threads arch=linux-ubuntu16.04-x86_64
                        ^gdbm@1.14.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                            ^readline@7.0%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                                ^ncurses@6.1%gcc@5.4.0~symlinks~termlib arch=linux-ubuntu16.04-x86_64
                ^automake@1.16.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64

You may want to add extra configuration to your environment. You can see how your environment is configured using spack config get:

$ spack config get
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
  # add package specs to the `specs` list
  specs: [tcl, trilinos, hdf5, gmp]

It turns out that this is a special configuration format where Spack stores the state for the environment. Currently, the file is just a spack: header and a list of specs. These are the roots.

You can edit this file to add your own custom configuration. Spack provides a shortcut to do that:

spack config edit

You should now see the same file, and edit it to look like this:

# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
  packages:
    all:
      providers:
        mpi: [mpich]

  # add package specs to the `specs` list
  specs: [tcl, trilinos, hdf5, gmp]

Now if we run spack spec again in the environment, specs will concretize with mpich as the MPI implementation:

$ spack spec hypre
Input spec
--------------------------------
hypre

Concretized
--------------------------------
hypre@2.15.1%gcc@5.4.0~debug~int64+internal-superlu+mpi+shared arch=linux-ubuntu16.04-x86_64
    ^mpich@3.2.1%gcc@5.4.0 device=ch3 +hydra netmod=tcp +pmi+romio~verbs arch=linux-ubuntu16.04-x86_64
        ^findutils@4.6.0%gcc@5.4.0 patches=84b916c0bf8c51b7e7b28417692f0ad3e7030d1f3c248ba77c42ede5c1c5d11e,bd9e4e5cc280f9753ae14956c4e4aa17fe7a210f55dd6c84aa60b12d106d47a2 arch=linux-ubuntu16.04-x86_64
            ^autoconf@2.69%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                ^m4@1.4.18%gcc@5.4.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=linux-ubuntu16.04-x86_64
                    ^libsigsegv@2.11%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                ^perl@5.26.2%gcc@5.4.0+cpanm patches=0eac10ed90aeb0459ad8851f88081d439a4e41978e586ec743069e8b059370ac +shared+threads arch=linux-ubuntu16.04-x86_64
                    ^gdbm@1.14.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                        ^readline@7.0%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
                            ^ncurses@6.1%gcc@5.4.0~symlinks~termlib arch=linux-ubuntu16.04-x86_64
                                ^pkgconf@1.4.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
            ^automake@1.16.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
            ^libtool@2.4.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
            ^texinfo@6.5%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
    ^openblas@0.3.3%gcc@5.4.0 cpu_target= ~ilp64 patches=47cfa7a952ac7b2e4632c73ae199d69fb54490627b66a62c681e21019c4ddc9d,714aea33692304a50bd0ccde42590c176c82ded4a8ac7f06e573dc8071929c33 +pic+shared threads=none ~virtual_machine arch=linux-ubuntu16.04-x86_64

In addition to the specs section, an environment’s configuration can contain any of the configuration options from Spack’s various config sections. You can add custom repositories, a custom install location, custom compilers, or custom external packages, in addition to the package preferences we show here.

But now we have a problem. We already installed part of this environment with openmpi, but now we want to install it with mpich.

You can run spack concretize inside of an environment to concretize all of its specs. We can run it here:

$ spack concretize -f
==> Concretizing tcl
[+]  qhwyccy  tcl@8.6.8%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  5nus6kn      ^zlib@1.2.11%gcc@5.4.0+optimize+pic+shared arch=linux-ubuntu16.04-x86_64
==> Concretizing trilinos
[+]  kqc52mo  trilinos@12.12.1%gcc@5.4.0~alloptpkgs+amesos+amesos2+anasazi+aztec+belos+boost build_type=RelWithDebInfo ~cgns~complex~dtk+epetra+epetraext+exodus+explicit_template_instantiation~float+fortran~fortrilinos+gtest+hdf5+hypre+ifpack+ifpack2~intrepid~intrepid2~isorropia+kokkos+metis~minitensor+ml+muelu+mumps~nox~openmp~phalanx~piro~pnetcdf~python~rol~rythmos+sacado~shards+shared~stk+suite-sparse~superlu~superlu-dist~teko~tempus+teuchos+tpetra~x11~xsdkflags~zlib+zoltan+zoltan2 arch=linux-ubuntu16.04-x86_64
[+]  zbgfxap      ^boost@1.68.0%gcc@5.4.0+atomic+chrono~clanglibcpp cxxstd=default +date_time~debug+exception+filesystem+graph~icu+iostreams+locale+log+math~mpi+multithreaded~numpy patches=2ab6c72d03dec6a4ae20220a9dfd5c8c572c5294252155b85c6874d97c323199 +program_options~python+random+regex+serialization+shared+signals~singlethreaded+system~taggedlayout+test+thread+timer~versionedlayout+wave arch=linux-ubuntu16.04-x86_64
[+]  ufczdvs          ^bzip2@1.0.6%gcc@5.4.0+shared arch=linux-ubuntu16.04-x86_64
[+]  2rhuivg              ^diffutils@3.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  5nus6kn          ^zlib@1.2.11%gcc@5.4.0+optimize+pic+shared arch=linux-ubuntu16.04-x86_64
[+]  otafqzh      ^cmake@3.12.3%gcc@5.4.0~doc+ncurses+openssl+ownlibs patches=dd3a40d4d92f6b2158b87d6fb354c277947c776424aa03f6dc8096cf3135f5d0 ~qt arch=linux-ubuntu16.04-x86_64
[+]  3o765ou          ^ncurses@6.1%gcc@5.4.0~symlinks~termlib arch=linux-ubuntu16.04-x86_64
[+]  fovrh7a              ^pkgconf@1.4.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  b4y3w3b          ^openssl@1.0.2o%gcc@5.4.0+systemcerts arch=linux-ubuntu16.04-x86_64
[+]  ic2kyoa              ^perl@5.26.2%gcc@5.4.0+cpanm patches=0eac10ed90aeb0459ad8851f88081d439a4e41978e586ec743069e8b059370ac +shared+threads arch=linux-ubuntu16.04-x86_64
[+]  q4fpyuo                  ^gdbm@1.14.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  nxhwrg7                      ^readline@7.0%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  jnw622j      ^glm@0.9.7.1%gcc@5.4.0 build_type=RelWithDebInfo arch=linux-ubuntu16.04-x86_64
[+]  xxd7syh      ^hdf5@1.10.4%gcc@5.4.0~cxx~debug~fortran+hl+mpi+pic+shared~szip~threadsafe arch=linux-ubuntu16.04-x86_64
[+]  p3f7p2r          ^mpich@3.2.1%gcc@5.4.0 device=ch3 +hydra netmod=tcp +pmi+romio~verbs arch=linux-ubuntu16.04-x86_64
[+]  d4iajxs              ^findutils@4.6.0%gcc@5.4.0 patches=84b916c0bf8c51b7e7b28417692f0ad3e7030d1f3c248ba77c42ede5c1c5d11e,bd9e4e5cc280f9753ae14956c4e4aa17fe7a210f55dd6c84aa60b12d106d47a2 arch=linux-ubuntu16.04-x86_64
[+]  3sx2gxe                  ^autoconf@2.69%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  suf5jtc                      ^m4@1.4.18%gcc@5.4.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=linux-ubuntu16.04-x86_64
[+]  fypapcp                          ^libsigsegv@2.11%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  rymw7im                  ^automake@1.16.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  o2pfwjf                  ^libtool@2.4.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  zs7a2pc                  ^texinfo@6.5%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  obewuoz      ^hypre@2.15.1%gcc@5.4.0~debug~int64~internal-superlu+mpi+shared arch=linux-ubuntu16.04-x86_64
[+]  cyeg2yi          ^openblas@0.3.3%gcc@5.4.0 cpu_target= ~ilp64 patches=47cfa7a952ac7b2e4632c73ae199d69fb54490627b66a62c681e21019c4ddc9d,714aea33692304a50bd0ccde42590c176c82ded4a8ac7f06e573dc8071929c33 +pic+shared threads=none ~virtual_machine arch=linux-ubuntu16.04-x86_64
[+]  gvyqldh      ^matio@1.5.9%gcc@5.4.0+hdf5+shared+zlib arch=linux-ubuntu16.04-x86_64
[+]  3wnvp4j      ^metis@5.1.0%gcc@5.4.0 build_type=Release ~gdb~int64 patches=4991da938c1d3a1d3dea78e49bbebecba00273f98df2a656e38b83d55b281da1 ~real64+shared arch=linux-ubuntu16.04-x86_64
[+]  cumcj5a      ^mumps@5.1.1%gcc@5.4.0+complex+double+float~int64~metis+mpi~parmetis~ptscotch~scotch+shared arch=linux-ubuntu16.04-x86_64
[+]  p7iln2p          ^netlib-scalapack@2.0.2%gcc@5.4.0 build_type=RelWithDebInfo ~pic+shared arch=linux-ubuntu16.04-x86_64
[+]  wmmx5sg      ^netcdf@4.6.1%gcc@5.4.0~dap~hdf4 maxdims=1024 maxvars=8192 +mpi~parallel-netcdf+shared arch=linux-ubuntu16.04-x86_64
[+]  jehtata      ^parmetis@4.0.3%gcc@5.4.0 build_type=RelWithDebInfo ~gdb patches=4f892531eb0a807eb1b82e683a416d3e35154a455274cf9b162fb02054d11a5b,50ed2081bc939269689789942067c58b3e522c269269a430d5d34c00edbc5870,704b84f7c7444d4372cb59cca6e1209df4ef3b033bc4ee3cf50f369bce972a9d +shared arch=linux-ubuntu16.04-x86_64
[+]  zaau4ki      ^suite-sparse@5.3.0%gcc@5.4.0~cuda~openmp+pic~tbb arch=linux-ubuntu16.04-x86_64
==> Concretizing hdf5
 -   zjgyn3w  hdf5@1.10.4%gcc@5.4.0~cxx~debug~fortran~hl+mpi+pic+shared~szip~threadsafe arch=linux-ubuntu16.04-x86_64
[+]  p3f7p2r      ^mpich@3.2.1%gcc@5.4.0 device=ch3 +hydra netmod=tcp +pmi+romio~verbs arch=linux-ubuntu16.04-x86_64
[+]  d4iajxs          ^findutils@4.6.0%gcc@5.4.0 patches=84b916c0bf8c51b7e7b28417692f0ad3e7030d1f3c248ba77c42ede5c1c5d11e,bd9e4e5cc280f9753ae14956c4e4aa17fe7a210f55dd6c84aa60b12d106d47a2 arch=linux-ubuntu16.04-x86_64
[+]  3sx2gxe              ^autoconf@2.69%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  suf5jtc                  ^m4@1.4.18%gcc@5.4.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=linux-ubuntu16.04-x86_64
[+]  fypapcp                      ^libsigsegv@2.11%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  ic2kyoa                  ^perl@5.26.2%gcc@5.4.0+cpanm patches=0eac10ed90aeb0459ad8851f88081d439a4e41978e586ec743069e8b059370ac +shared+threads arch=linux-ubuntu16.04-x86_64
[+]  q4fpyuo                      ^gdbm@1.14.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  nxhwrg7                          ^readline@7.0%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  3o765ou                              ^ncurses@6.1%gcc@5.4.0~symlinks~termlib arch=linux-ubuntu16.04-x86_64
[+]  fovrh7a                                  ^pkgconf@1.4.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  rymw7im              ^automake@1.16.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  o2pfwjf              ^libtool@2.4.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  zs7a2pc              ^texinfo@6.5%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  5nus6kn      ^zlib@1.2.11%gcc@5.4.0+optimize+pic+shared arch=linux-ubuntu16.04-x86_64
==> Concretizing gmp
[+]  qc4qcfz  gmp@6.1.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  3sx2gxe      ^autoconf@2.69%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  suf5jtc          ^m4@1.4.18%gcc@5.4.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=linux-ubuntu16.04-x86_64
[+]  fypapcp              ^libsigsegv@2.11%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  ic2kyoa          ^perl@5.26.2%gcc@5.4.0+cpanm patches=0eac10ed90aeb0459ad8851f88081d439a4e41978e586ec743069e8b059370ac +shared+threads arch=linux-ubuntu16.04-x86_64
[+]  q4fpyuo              ^gdbm@1.14.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  nxhwrg7                  ^readline@7.0%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  3o765ou                      ^ncurses@6.1%gcc@5.4.0~symlinks~termlib arch=linux-ubuntu16.04-x86_64
[+]  fovrh7a                          ^pkgconf@1.4.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  rymw7im      ^automake@1.16.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  o2pfwjf      ^libtool@2.4.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64

Now, all the specs in the environemnt are concrete and ready to be installed wiht mpich as the MPI immplementation.

Normally, we could just run spack config edit, edit the environment configuration, spack add some specs, and install.

But, when we already have installed packages in the environment, we have to force everything in the environment to be re-concretized using spack concretize -f. Then we can re-run spack install.

spack.yaml and spack.lock

So far we’ve shown you how to interact with environments from the command line, but they also have a file-based interface that can be used by developers and admins to manage workflows for projects.

In this section we’ll dive a little deeper to see how environments are implemented, and how you could use this in your day-to-day development.

spack.yaml

Earlier, we changed an environment’s configuration using spack config edit. We were actually editing a special file called spack.yaml. Let’s take a look.

We can get directly to the current environment’s location using spack cd:

$ spack cd -e myproject
$ pwd
~/spack/var/spack/environments/myproject
$ ls
spack.lock  spack.yaml

We notice two things here. First, the environment is just a directory inside of var/spack/environments within the Spack installation. Second, it contains two important files: spack.yaml and spack.lock.

spack.yaml is the configuration file for environments that we’ve already seen, but it does not have to live inside Spack. If you create an environment using spack env create, it is managed by Spack in the var/spack/environments directory, and you can refer to it by name.

You can actually put a spack.yaml file anywhere, and you can use it to bundle an environment, or a list of dependencies to install, with your project. Let’s make a simple project:

$ cd
$ mkdir code
$ cd code
$ spack env create -d .
==> Created environment in ~/code

Here, we made a new directory called code, and we used the -d option to create an environment in it.

What really happened?

$ ls
spack.yaml
$ cat spack.yaml
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
  # add package specs to the `specs` list
  specs: []

Spack just created a spack.yaml file in the code directory, with an empty list of root specs. Now we have a Spack environment, in a directory, that we can use to manage dependencies. Suppose your project depends on boost, trilinos, and openmpi. You can add these to your spec list:

# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
  # add package specs to the `specs` list
  specs:
  - boost
  - trilinos
  - openmpi

And now anyone who uses the code repository can use this format to install the project’s dependencies. They need only clone the repository, cd into it, and type spack install:

$ spack install
==> Concretizing boost
[+]  zbgfxap  boost@1.68.0%gcc@5.4.0+atomic+chrono~clanglibcpp cxxstd=default +date_time~debug+exception+filesystem+graph~icu+iostreams+locale+log+math~mpi+multithreaded~numpy patches=2ab6c72d03dec6a4ae20220a9dfd5c8c572c5294252155b85c6874d97c323199 +program_options~python+random+regex+serialization+shared+signals~singlethreaded+system~taggedlayout+test+thread+timer~versionedlayout+wave arch=linux-ubuntu16.04-x86_64
[+]  ufczdvs      ^bzip2@1.0.6%gcc@5.4.0+shared arch=linux-ubuntu16.04-x86_64
[+]  2rhuivg          ^diffutils@3.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  5nus6kn      ^zlib@1.2.11%gcc@5.4.0+optimize+pic+shared arch=linux-ubuntu16.04-x86_64
==> Concretizing trilinos
[+]  rlsruav  trilinos@12.12.1%gcc@5.4.0~alloptpkgs+amesos+amesos2+anasazi+aztec+belos+boost build_type=RelWithDebInfo ~cgns~complex~dtk+epetra+epetraext+exodus+explicit_template_instantiation~float+fortran~fortrilinos+gtest+hdf5+hypre+ifpack+ifpack2~intrepid~intrepid2~isorropia+kokkos+metis~minitensor+ml+muelu+mumps~nox~openmp~phalanx~piro~pnetcdf~python~rol~rythmos+sacado~shards+shared~stk+suite-sparse~superlu~superlu-dist~teko~tempus+teuchos+tpetra~x11~xsdkflags~zlib+zoltan+zoltan2 arch=linux-ubuntu16.04-x86_64
[+]  zbgfxap      ^boost@1.68.0%gcc@5.4.0+atomic+chrono~clanglibcpp cxxstd=default +date_time~debug+exception+filesystem+graph~icu+iostreams+locale+log+math~mpi+multithreaded~numpy patches=2ab6c72d03dec6a4ae20220a9dfd5c8c572c5294252155b85c6874d97c323199 +program_options~python+random+regex+serialization+shared+signals~singlethreaded+system~taggedlayout+test+thread+timer~versionedlayout+wave arch=linux-ubuntu16.04-x86_64
[+]  ufczdvs          ^bzip2@1.0.6%gcc@5.4.0+shared arch=linux-ubuntu16.04-x86_64
[+]  2rhuivg              ^diffutils@3.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  5nus6kn          ^zlib@1.2.11%gcc@5.4.0+optimize+pic+shared arch=linux-ubuntu16.04-x86_64
[+]  otafqzh      ^cmake@3.12.3%gcc@5.4.0~doc+ncurses+openssl+ownlibs patches=dd3a40d4d92f6b2158b87d6fb354c277947c776424aa03f6dc8096cf3135f5d0 ~qt arch=linux-ubuntu16.04-x86_64
[+]  3o765ou          ^ncurses@6.1%gcc@5.4.0~symlinks~termlib arch=linux-ubuntu16.04-x86_64
[+]  fovrh7a              ^pkgconf@1.4.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  b4y3w3b          ^openssl@1.0.2o%gcc@5.4.0+systemcerts arch=linux-ubuntu16.04-x86_64
[+]  ic2kyoa              ^perl@5.26.2%gcc@5.4.0+cpanm patches=0eac10ed90aeb0459ad8851f88081d439a4e41978e586ec743069e8b059370ac +shared+threads arch=linux-ubuntu16.04-x86_64
[+]  q4fpyuo                  ^gdbm@1.14.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  nxhwrg7                      ^readline@7.0%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  jnw622j      ^glm@0.9.7.1%gcc@5.4.0 build_type=RelWithDebInfo arch=linux-ubuntu16.04-x86_64
[+]  oqwnui7      ^hdf5@1.10.4%gcc@5.4.0~cxx~debug~fortran+hl+mpi+pic+shared~szip~threadsafe arch=linux-ubuntu16.04-x86_64
[+]  3njc4q5          ^openmpi@3.1.3%gcc@5.4.0~cuda+cxx_exceptions fabrics= ~java~legacylaunchers~memchecker~pmi schedulers= ~sqlite3~thread_multiple+vt arch=linux-ubuntu16.04-x86_64
[+]  43tkw5m              ^hwloc@1.11.9%gcc@5.4.0~cairo~cuda+libxml2+pci+shared arch=linux-ubuntu16.04-x86_64
[+]  5urc6tc                  ^libpciaccess@0.13.5%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  o2pfwjf                      ^libtool@2.4.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  suf5jtc                          ^m4@1.4.18%gcc@5.4.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=linux-ubuntu16.04-x86_64
[+]  fypapcp                              ^libsigsegv@2.11%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  milz7fm                      ^util-macros@1.19.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  wpexsph                  ^libxml2@2.9.8%gcc@5.4.0~python arch=linux-ubuntu16.04-x86_64
[+]  teneqii                      ^xz@5.2.4%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  ft463od                  ^numactl@2.0.11%gcc@5.4.0 patches=592f30f7f5f757dfc239ad0ffd39a9a048487ad803c26b419e0f96b8cda08c1a arch=linux-ubuntu16.04-x86_64
[+]  3sx2gxe                      ^autoconf@2.69%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  rymw7im                      ^automake@1.16.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  fshksdp      ^hypre@2.15.1%gcc@5.4.0~debug~int64~internal-superlu+mpi+shared arch=linux-ubuntu16.04-x86_64
[+]  cyeg2yi          ^openblas@0.3.3%gcc@5.4.0 cpu_target= ~ilp64 patches=47cfa7a952ac7b2e4632c73ae199d69fb54490627b66a62c681e21019c4ddc9d,714aea33692304a50bd0ccde42590c176c82ded4a8ac7f06e573dc8071929c33 +pic+shared threads=none ~virtual_machine arch=linux-ubuntu16.04-x86_64
[+]  lmzdgss      ^matio@1.5.9%gcc@5.4.0+hdf5+shared+zlib arch=linux-ubuntu16.04-x86_64
[+]  3wnvp4j      ^metis@5.1.0%gcc@5.4.0 build_type=Release ~gdb~int64 patches=4991da938c1d3a1d3dea78e49bbebecba00273f98df2a656e38b83d55b281da1 ~real64+shared arch=linux-ubuntu16.04-x86_64
[+]  acsg2dz      ^mumps@5.1.1%gcc@5.4.0+complex+double+float~int64~metis+mpi~parmetis~ptscotch~scotch+shared arch=linux-ubuntu16.04-x86_64
[+]  wotpfwf          ^netlib-scalapack@2.0.2%gcc@5.4.0 build_type=RelWithDebInfo ~pic+shared arch=linux-ubuntu16.04-x86_64
[+]  mhm4izp      ^netcdf@4.6.1%gcc@5.4.0~dap~hdf4 maxdims=1024 maxvars=8192 +mpi~parallel-netcdf+shared arch=linux-ubuntu16.04-x86_64
[+]  uv6h3sq      ^parmetis@4.0.3%gcc@5.4.0 build_type=RelWithDebInfo ~gdb patches=4f892531eb0a807eb1b82e683a416d3e35154a455274cf9b162fb02054d11a5b,50ed2081bc939269689789942067c58b3e522c269269a430d5d34c00edbc5870,704b84f7c7444d4372cb59cca6e1209df4ef3b033bc4ee3cf50f369bce972a9d +shared arch=linux-ubuntu16.04-x86_64
[+]  zaau4ki      ^suite-sparse@5.3.0%gcc@5.4.0~cuda~openmp+pic~tbb arch=linux-ubuntu16.04-x86_64
==> Concretizing openmpi
[+]  3njc4q5  openmpi@3.1.3%gcc@5.4.0~cuda+cxx_exceptions fabrics= ~java~legacylaunchers~memchecker~pmi schedulers= ~sqlite3~thread_multiple+vt arch=linux-ubuntu16.04-x86_64
[+]  43tkw5m      ^hwloc@1.11.9%gcc@5.4.0~cairo~cuda+libxml2+pci+shared arch=linux-ubuntu16.04-x86_64
[+]  5urc6tc          ^libpciaccess@0.13.5%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  o2pfwjf              ^libtool@2.4.6%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  suf5jtc                  ^m4@1.4.18%gcc@5.4.0 patches=3877ab548f88597ab2327a2230ee048d2d07ace1062efe81fc92e91b7f39cd00,c0a408fbffb7255fcc75e26bd8edab116fc81d216bfd18b473668b7739a4158e,fc9b61654a3ba1a8d6cd78ce087e7c96366c290bc8d2c299f09828d793b853c8 +sigsegv arch=linux-ubuntu16.04-x86_64
[+]  fypapcp                      ^libsigsegv@2.11%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  fovrh7a              ^pkgconf@1.4.2%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  milz7fm              ^util-macros@1.19.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  wpexsph          ^libxml2@2.9.8%gcc@5.4.0~python arch=linux-ubuntu16.04-x86_64
[+]  teneqii              ^xz@5.2.4%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  5nus6kn              ^zlib@1.2.11%gcc@5.4.0+optimize+pic+shared arch=linux-ubuntu16.04-x86_64
[+]  ft463od          ^numactl@2.0.11%gcc@5.4.0 patches=592f30f7f5f757dfc239ad0ffd39a9a048487ad803c26b419e0f96b8cda08c1a arch=linux-ubuntu16.04-x86_64
[+]  3sx2gxe              ^autoconf@2.69%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  ic2kyoa                  ^perl@5.26.2%gcc@5.4.0+cpanm patches=0eac10ed90aeb0459ad8851f88081d439a4e41978e586ec743069e8b059370ac +shared+threads arch=linux-ubuntu16.04-x86_64
[+]  q4fpyuo                      ^gdbm@1.14.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  nxhwrg7                          ^readline@7.0%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
[+]  3o765ou                              ^ncurses@6.1%gcc@5.4.0~symlinks~termlib arch=linux-ubuntu16.04-x86_64
[+]  rymw7im              ^automake@1.16.1%gcc@5.4.0 arch=linux-ubuntu16.04-x86_64
==> Installing environment ~/code
==> boost is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/boost-1.68.0-zbgfxapchxa4awxdwpleubfuznblxzvt
==> trilinos is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/trilinos-12.12.1-rlsruavxqvwk2tgxzxboclbo6ykjf54r
==> openmpi is already installed in ~/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openmpi-3.1.3-3njc4q5pqdpptq6jvqjrezkffwokv2sx

Spack concretizes the specs in the spack.yaml file and installs them.

What happened here? If you cd into a directory tha has a spack.yaml file in it, Spack considers this directory’s environment to be activated. The directory does not have to live within Spack; it can be anywhere.

So, from ~/code, we can actually manipulate spack.yaml using spack add and spack remove (just like managed environments):

$ spack add hdf5@5.5.1
==> Adding hdf5 to environment ~/code
$ cat spack.yaml
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
  # add package specs to the `specs` list
  specs:
  - boost
  - trilinos
  - openmpi
  - hdf5@5.5.1

$ spack remove hdf5
==> Removing hdf5 from environment ~/code
$ cat spack.yaml
# This is a Spack Environment file.
#
# It describes a set of packages to be installed, along with
# configuration settings.
spack:
  # add package specs to the `specs` list
  specs:
  - boost
  - trilinos
  - openmpi

spack.lock

Ok, we’ve covered managed environments, environments in directories, and the last thing we’ll cover is spack.lock. You may remember that when we ran spack install, Spack concretized all the specs in the spack.yaml file and installed them.

Whenever we concretize Specs in an environment, all concrete specs in the environment are written out to a spack.lock file alongside spack.yaml. The spack.lock file is not really human-readable like the spack.yaml file. It is a json format that contains all the information that we need to reproduce the build of an environment:

$ head spack.lock
{
  "concrete_specs": {
   "teneqii2xv5u6zl5r6qi3pwurc6pmypz": {
    "xz": {
      "version": "5.2.4",
      "arch": {
        "platform": "linux",
        "platform_os": "ubuntu16.04",
      "target": "x86_64"
 },
 ...

spack.yaml and spack.lock correspond to two fundamental concepts in Spack, but for environments:

  • spack.yaml is the set of abstract specs and configuration that you want to install.
  • spack.lock is the set of all fully concretized specs generated from concretizing spack.yaml

Using either of these, you can recreate an environment that someone else built. spack env create takes an extra optional argument, which can be either a spack.yaml or a spack.lock file:

$ spack env create my-project spack.yaml

$ spack env create my-project spack.lock

Both of these create a new environment called my-project, but which one you choose to use depends on your needs:

  1. copying the yaml file allows someone else to build your requirements, potentially a different way.
  2. copying the lock file allows someone else to rebuild your installation exactly as you built it.

The first use case can re-concretize the same specs on new platforms in order to build, but it will preserve the abstract requirements. The second use case (currently) requires you to be on the same machine, but it retains all decisions made during concretization and is faithful to a prior install.