View source for SPACK on JLab ifarm


= Using the JLab SPACK Repository =
== Overview ==

[https://spack.io/ SPACK] is a package manager used to maintain multiple versions of software compiled with various compilers for various OSes. The EPSCI group takes the primary responsibility for maintaining the SPACK repository at JLab. SPACK has a rich feature set that allows a lot of flexibility in how one can use it to manage their software. This page describes details of how SPACK is implemented at JLab for the ENP program.

There are two primary use cases for the software built with the SPACK system:

# Users on the JLab SciComp farm (ifarm) want to use the pre-built binary versions 
# Users running offsite want to use the pre-built binary versions on their local computers

These are satisfied by using ''/cvmfs''.

== Quickstart ==

The spack builds may be used directly from the host OS or via a container. In both cases, the software is installed in network mounted ''/cvmfs/oasis.opensciencegrid.org/jlab/epsci/spack'' so the host will need to have that set up and working. It is recommended to use the container since there may be system packages installed there that the spack packages require. 

=== Using Podman ===

''[https://podman.io/ podman]'' is a containerization system available on the ifarm. It should already be in your PATH. It is able to run Docker or Apptainer containers as well as build Docker images. 

Images for various OSes can be found in the ''/cvmfs/oasis.opensciencegrid.org/jlab/epsci/spack/images'' directory. Note that in order to access the ''/cvmfs'' directory inside the container, you will need to bind it using the ''-v /cvmfs/oasis.opensciencegrid.org:/cvmfs/oasis.opensciencegrid.org'' option. Once the container has started, you will need to setup the spack environment by sourcing the correct ''setup_env.sh'' script.

   podman run -it --rm -v /cvmfs/oasis.opensciencegrid.org:/cvmfs/oasis.opensciencegrid.org:Z jeffersonlab/epsci-almalinux:9.2-20230718
   bash-5.1$ source /cvmfs/oasis.opensciencegrid.org/jlab/epsci/almalinux/9.2-20230718/share/spack/setup-env.sh

To see available spack packages, run ''spack find''. Below is an example of the output.

   Singularity> spack find       
   -- linux-ubuntu22.04-x86_64 / gcc@11.3.0 ------------------------
   berkeley-db@18.1.40                 geant4-data@11.0.0    libxml2@2.10.3           py-wheel@0.37.1
   binutils@2.38                       gettext@0.21.1        libxmu@1.1.2             python@3.10.8
   bison@3.8.2                         glproto@1.4.17        libxrandr@1.5.0          randrproto@1.5.0
   bzip2@1.0.8                         glx@1.4               libxrender@0.9.10        re2c@2.2
   ca-certificates-mozilla@2022-10-11  hwloc@2.8.0           libxt@1.1.5              readline@8.2
   clhep@2.4.6.0                       inputproto@2.3.2      llvm@14.0.6              renderproto@0.11.1
   cmake@3.25.1                        kbproto@1.0.7         lmod@8.7.2               sqlite@3.40.0
   curl@7.85.0                         libbsd@0.11.5         lua@5.4.4                tar@1.34
   diffutils@3.8                       libedit@3.1-20210216  lua-luafilesystem@1_8_0  tcl@8.6.12
   expat@2.5.0                         libffi@3.4.2          lua-luaposix@35.0        texinfo@7.0
   findutils@4.9.0                     libice@1.0.9          m4@1.4.19                unzip@6.0
   flex@2.6.3                          libiconv@1.16         mesa@22.1.2              util-linux-uuid@2.38.1
   g4abla@3.1                          libmd@1.0.4           mesa-glu@9.0.2           util-macros@1.19.3
   g4emlow@8.0                         libpciaccess@0.16     meson@1.0.0              xcb-proto@1.14.1
   g4ensdfstate@2.3                    libpthread-stubs@0.4  ncurses@6.3              xerces-c@3.2.3
   g4incl@1.0                          libsigsegv@2.13       ninja@1.11.1             xextproto@7.3.0
   g4ndl@4.6                           libsm@1.2.3           openssl@1.1.1s           xproto@7.0.31
   g4particlexs@4.0                    libtool@2.4.7         perl@5.36.0              xrandr@1.5.0
   g4photonevaporation@5.7             libunwind@1.6.2       perl-data-dumper@2.173   xtrans@1.3.5
   g4pii@1.3                           libx11@1.7.0          pigz@2.7                 xz@5.2.7
   g4radioactivedecay@5.6              libxau@1.0.8          pkgconf@1.8.0            zlib@1.2.13
   g4realsurface@2.2                   libxcb@1.14           py-mako@1.2.2            zstd@1.5.2
   g4saiddata@2.0                      libxcrypt@4.4.33      py-markupsafe@2.1.1
   gdbm@1.23                           libxdmcp@1.1.2        py-pip@22.2.2
   geant4@11.0.3                       libxext@1.3.3         py-setuptools@65.5.0
   ==> 97 installed packages

To load a package, use the ''spack load'' command. For example:

   Singularity> spack load geant4

Note that this may pull in other dependency packages. For example, ''python@3.10.8'' will be loaded by the above, superseding the Ubuntu 22.04 system installed python 3.10.6.

   

=== Using via host OS ===

WARNING: Using spack directly from the host OS is deprecated. It is recommended that you use it from a container.

The recommended way to set up your environment is with one of the following: 

   [bash]  source /cvmfs/oasis.opensciencegrid.org/jlab/epsci/spack_env.sh  lmod gcc/9.3.0
   [tcsh]  source /cvmfs/oasis.opensciencegrid.org/jlab/epsci/spack_env.csh lmod gcc/9.3.0

Note that the above may take a few seconds to complete, but it sets up a user-friendly package naming scheme for "module load". If you want quicker startup and are willing to live with package names that include long hashes, then source the script with no arguments:

   [bash]  source /cvmfs/oasis.opensciencegrid.org/jlab/epsci/spack_env.sh
   [tcsh]  source /cvmfs/oasis.opensciencegrid.org/jlab/epsci/spack_env.csh

Other useful commands:

   module avail                # List available packages
   module load packagename     # Load a package (optionally specify version number)
   module unload packagename   # Unload a package that was previously loaded

The following operating systems are supported:

{| class="wikitable"
|+ Supported Operating Systems
! OS
! support start date
! status
|-
| ubuntu/22.04
| December 29, 2022
| current|
|-
| centos/7.7.1908
| March 31, 2021
| deprecated
|-
| centos/8.3.2011
| March 31, 2021
| deprecated
|-
| ubuntu/21.04
| March 31, 2021
| deprecated
|}

== CVMFS Client Configuration ==

If you are working on the JLab ifarm computers than CVMFS is already installed and configured. This is nothing else you need to do. CVMFS may also already be available on many remote HPC sites (e.g. NERSC). Check the site's specific documentation or simply look for the /cvmfs/oasis.opensciencegrid.org directory.

To mount the public, read-only CVMFS volume that contains the pre-built binaries see the instructions in one of the following sections for your specific platform. 

''The most up to date instructions on installing and configuring the CVMFS client software can be found on the [https://cernvm.cern.ch/fs/ CVMFS website].''

<hr width="50%">
=== Linux ===

Here are instructions for installing on a CentOS or RedHat system (personal laptop or desktop)

1. Install the pointer to the CVMFS repo and then install cvmfs itself. After it is installed, generate a default config file.

   sudo yum install https://ecsft.cern.ch/dist/cvmfs/cvmfs-release/cvmfs-release-latest.noarch.rpm
   sudo yum install -y cvmfs
   cvmfs_config setup

2. Create a config file '''''/etc/cvmfs/default.local''''' with the following content (you need to do this with sudo):

  CVMFS_REPOSITORIES=oasis.opensciencegrid.org
  CVMFS_HTTP_PROXY=DIRECT
  CVMFS_CLIENT_PROFILE=single

3. Restart the autofs service

   systemctl restart autofs

4. Make the mount point and mount the cvmfs disk

  sudo mkdir -p /cvmfs/oasis.opensciencegrid.org
  sudo mount -t cvmfs oasis.opensciencegrid.org /cvmfs/oasis.opensciencegrid.org

<hr width="50%">

=== Mac OS X ===
To use CVMFS on Mac OS X, you need to install the ''MacFUSE'' package and then the ''cvmfs'' package. You should then reboot so everything will load properly. The step-by-step instructions follow. 

1. Download and install the [https://osxfuse.github.io/ macFUSE package]

2. Download and install the cvmfs package with the following (Note that downloading the cvmfs package via ''curl'' apparently avoids some signature security issue on Mac OS X that you would get if downloaded via web-browser. Don't ask me how.)

  curl -o ~/Downloads/cvmfs-2.7.5.pkg https://ecsft.cern.ch/dist/cvmfs/cvmfs-2.7.5/cvmfs-2.7.5.pkg
  open cvmfs-2.7.5.pkg

3. Create a config file '''''/etc/cvmfs/default.local''''' with the following content (you need to do this with sudo):
  CVMFS_REPOSITORIES=oasis.opensciencegrid.org
  CVMFS_HTTP_PROXY=DIRECT

4. Restart the computer

5. Create the mount point and mount oasis with:
  sudo mkdir -p /cvmfs/oasis.opensciencegrid.org
  sudo mount -t cvmfs oasis.opensciencegrid.org /cvmfs/oasis.opensciencegrid.org

If it all works you should see something like this:

  >sudo mount -t cvmfs oasis.opensciencegrid.org /cvmfs/oasis.opensciencegrid.org
  CernVM-FS: running with credentials 10000:10000
  CernVM-FS: loading Fuse module... done
  CernVM-FS: mounted cvmfs on /Users/Shared/cvmfs/oasis.opensciencegrid.org

<hr width="50%">
=== Docker ===

There are actually two options for using CVMFS inside a Docker container:
# Install CVMFS on the host and simply bind the /cvmfs directory to the same directory inside the container
# Run the CVMFS software inside the container and mount it there.

Option 1 is preferred since any caching of the files is done by the host and and so does not disappear when the container goes away. It also can be used with any image and does not require another image to be created with the CVMFS software installed. To implement option 1, first mount CMVFS on the host using the above instructions for your host platform. Then, when you start the container, give the docker command an argument of ''-v /cvmfs:/cvmfs''.

Option 2 can be convenient if you have trouble getting CVMFS working on the host. There are actually two methods here. One is to use the pre-made Docker container [https://cvmfs.readthedocs.io/en/stable/cpt-quickstart.html#docker-container as described in the CVMFS documentation]. You may create an image based on this or even use it as-is to supply /cvmfs to the host and then use option 1 above.

The second method is to create a new image from scratch containing the necessary software. This method has worked in the past, though there may be easier ways of doing it today. Here are the instructions though in case all of the other above methods fail.

Unfortunately, there are a couple of steps that cannot be done when the image is created and must be implemented when the container is created. A working example with some comments can be found here: 

[https://github.com/faustus123/hdcontainers/tree/master/Docker_cvmfs https://github.com/faustus123/hdcontainers/tree/master/Docker_cvmfs]


== Running untethered (no CVMFS) ==
<div id="untethered"></div>

Running untethered means installing the packages on your local computer so you can still run the software even with no internet connection. It is stated up front that this is unlikely to work for numerous reasons, but for those who like punishing themselves, here is some info that may help get you going. It goes without saying that none of this is recommended.

The main issue with installing locally is that many packages build their installation paths into their installed scripts and binaries. While spack does have mechanisms to try and fix this, they can fail if the directory path is either too long or too short. Your best chances of success will come if you create a local directory path that matches exactly what it would be if /CVMFS were mounted. Here are some example instructions: 

   mkdir -p /cvmfs/oasis.opensciencegrid.org/jlab/epsci/centos/
   git clone --depth 1 https://github.com/spack/spack.git /cvmfs/oasis.opensciencegrid.org/jlab/epsci/centos/7.7.1908
   source /cvmfs/oasis.opensciencegrid.org/jlab/epsci/centos/7.7.1908/share/spack/setup-env.sh # or setup-env.csh
   spack mirror add jlab-public https://spack.jlab.org/mirror
   spack install -f -o -u clhep   # This should install "CLHEP" locally using the pre-built binaries 




<!-- ================================================================================================ -->
<hr>

= Administration of the SPACK Repository =
The following sections describe various aspects of creating and managing the JLab SPACK repository. There are a number of choices that were made in how this was set up so this documents those since they may not all be obvious by simply looking at directory structures and config. files.

Perhaps one of the most important pieces of information is that scripts and tools used to help us maintain spack at JLab are kept in a github repository:

   [https://github.com/JeffersonLab/epsci-spack/tree/main/admin https://github.com/JeffersonLab/epsci-spack]

which is checked out on the CUE in ''/scigroup/spack/admin''.

== Organizational Overview ==
The organization of the spack binaries is as follows:

# Packages are built using podman containers
#* Containers bind the ''/scigroup/cvmfs'' subdirectory to be at ''/cvmfs/oasis.opensciencegrid.org/jlab'' inside the container
#* This allows absolute paths that start with /cvmfs to be writable in the build/install process
#* The ''/scigroup/cvmfs/epsci'' directory is exported to CVMFS so it can be mounted read-only from anywhere
#* The export is done every 4 hours via cronjob. Thus, newly built packages will not be immediately accessible.
#** Wes Moore set this up and can increase frequency if needed.
# A separate spack repository is maintained for every platform (e.g. centos/7.7.1908 is separate from centos/8.0.2011)
#* This was a choice made on our end to segregate the binaries and make it easier to add and drop support for platforms in the future.
# In addition to the [https://github.com/spack/spack global spack repository], we also include the [https://github.com/eic/eic-spack eic-spack] and [https://github.com/JeffersonLab/epsci-spack epsci-spack] repositories.
#* This allows us to pull from the eic-spack package configurations and maintain our own package configurations.
# Users will access the software via the ''/cvmfs'' directory.
#* The SciComp computers (e.g. ifarm1901) all mount ''/cvmfs''
#* Users can also install the CVMFS client on their personal laptop or desktop to access the software.
# The packages are exported to a ''build cache'' accessible from https://spack.jlab.org/mirror
#* We do this only because it is simple and doesn't cost us anything significant. We discourage its use and may remove it in the future.

== Setting up a new platform ==

A platform here is defined as the OS name and version. e.g. almalinux:9.3. The specific versions are chosen based on official Docker images maintained by the OS vendors on [https://hub.docker.com Docker Hub](for examples, look [https://hub.docker.com/_/almalinux/tags here]). For platforms corresponding to the JLab SciComp farm, the exact tags used are selected to be as close as possible to what is being used there.

The basic steps are to create a docker image and then run it with [https://podman.io/ podman] in user mode to setup a new [https://spack.io spack] instance ( helper script is available for this). Packages will then be built with the native compiler for the platform. Optionally, other compiler versions may be built using spack and then those compilers used to build versions of the spack packages compatible with that compiler.

Note that [https://apptainer.org/ apptainer/singularity] support here is deprecated in favor of podman in user mode.

The following sections describe these steps in some detail.

=== Creating a new container Image ===
<div id="Apptainer"></div>
The current ifarm architecture is amd64 so that is the only required platform to build for. However, it is easy enough to build for arm64 as well which may be useful in the future so we do a multi-platform build of the container with Docker.

The ''Dockerfile''s used to create the Docker images are kept in the git-hub repository [https://github.com/JeffersonLab/epsci-containers ''"epsci-containers"'']. They are also copied into the image itself so one can always access the Dockerfile used to create an image via ''/container/Dockerfile.*'' within a container. The Docker images are created with only a few system software packages installed. Mainly a C++ compiler, version control tools (e.g. git and svn), python, and a couple of other tools needed for building packages (e.g. cmake). Below is an example of a Dockerfile (click right-hand side to view).

<div class="toccolours mw-collapsible mw-collapsed">
EXAMPLE Dockerfile. (Click "Expand" to the right to see the example -->):

<div class="mw-collapsible-content">
<pre>
#--------------------------------------------------------------------------
# almalinux build environment
#
# 
# This Dockerfile will produce an image suitable for compiling software.
# The image will gave a C/C++ and Fortran compiler as well as python,
# It will also contain version control software (e.g. git and svn).
#
# The commands below are simplified by setting this environment variable:
#
#   export MYOS=almalinux:9.3
#   export MYOS_=almalinux-9.3
#
# The instructions below give a few options for building the image using
# either podman or docker. Both support multi-platform builds, but podman
# on ifarm only seems to support the native architecture while docker
# is able to build multiple. Thus, it is recommended to build using docker
# on your local desktop/laptop.
#--------------------------------------------------------------------------
#
#  These instructions are for a multi-architecture docker build:
#
#   docker buildx create --name mybuilder
#   docker buildx use mybuilder
#   docker buildx inspect --bootstrap
#   docker buildx build --platform linux/arm64,linux/amd64 -t jeffersonlab/epsci-${MYOS} --push -f Dockerfile.${MYOS_} .
#
#--------------------------------------------------------------------------
#
#  These instructions are for building with podman.
#
#  Note that this can be used to build multi-architecture by using a 
#  comma separated list for the platform (e.g. linux/amd64,linux/arm64).
#  ifarm though is not able to handle this so these build only for amd64.
#
#   podman manifest create epsci-${MYOS}
#   podman build --platform linux/amd64 --manifest epsci-${MYOS} -f Dockerfile.almalinux.9.3 .
#   podman manifest push epsci-${MYOS} docker://jeffersonlab/epsci-${MYOS}
#
#--------------------------------------------------------------------------
#
#  These instructions are for the classic single architecture docker build.
#  They also work for podman by just replacing "docker" with "podman".
#  This is mainly informational as it is recommended to do a multi-architecture
#  build using one of the above.
#
#   docker build -t epsci-${MYOS} -t jeffersonlab/epsci-${MYOS} -f Dockerfile.${MYOS} .
#   docker push jeffersonlab/epsci-${MYOS}
#
#--------------------------------------------------------------------------
# This is how you can pull the image into an apptainer container on ifarm:
#
#   cd /scigroup/cvmfs/epsci/spack/images
#   apptainer build epsci-${MYOS_}.img docker://jeffersonlab/epsci-${MYOS}
#
#--------------------------------------------------------------------------

FROM almalinux:9.3

# Python3 requires the timezone be set and will try and prompt for it.
ENV TZ=US/Eastern
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone

# Install compiler and code management tools
RUN dnf -y groupinstall 'Development Tools' \
	&& dnf -y install --allowerasing gcc-gfortran python3 git subversion curl which \
	&& dnf clean all

COPY Dockerfile.almalinux.9.3 /container/Dockerfile.almalinux.9.3
RUN ln -s /root /home/root
RUN ln -s /root /home/0

CMD ["/bin/bash"]
</pre>
</div>

</div>


First, create a Docker image. To do this, you need access to a computer with Docker installed. This generally needs to be a personal desktop or laptop since Docker requires root access and is therefore not available on the public machines like ''ifarm''. If you do not have access to such a machine, you can use podman to build the image for just the amd64 platform (see instructions inside the Dockerfile.) Here is an example of the steps you might go through if creating an image for a version of almalinux. This assumes you are starting on a computer with Docker installed and running.

NOTE: These instructions build a multi-architecture image for both '''amd64''' and '''arm64''' that gets pushed directly to Dockerhub. 

<pre>
# export MYOS=almalinux:9.3
# export MYOS_=almalinux.9.3
# git clone https://github.com/JeffersonLab/epsci-containers
# cd epsci-containers/base
# cp Dockerfile.almalinux.9.2-20230718 Dockerfile.${MYOS_}
# ''edit Dockerfile.${MYOS_} to replace the version numbers with the new ones. They appear in a few places so better to do global replace''
# docker buildx create --name mybuilder
# docker buildx use mybuilder
# docker buildx inspect --bootstrap
# docker buildx build --platform linux/arm64,linux/amd64 -t jeffersonlab/epsci-${MYOS} --push -f Dockerfile.${MYOS_} .
# ssh ifarm
# cd /scigroup/spack/images
# mkdir /scratch/${USER}/tmp
# apptainer build --tmpdir /scratch/${USER}/tmp epsci-${MYOS_}.img docker://jeffersonlab/epsci-${MYOS}
# cp -rp epsci-${MYOS_}.img /scigroup/cvmfs/epsci/singularity/images
</pre>

=== Initializing the new platform configuration ===
<div id="add_to_platform"></div>
There are some pitfalls that are easy to fall into when trying to setup a new platform. Particularly
if you want to build using a non-default compiler. To ameliorate this several administration scripts
have been written to make it as turnkey as possible.

Step-by-step instructions are below, but you may find some useful details in the comments at the
top of the script: [https://github.com/JeffersonLab/epsci-spack/blob/main/admin/mnp.sh /scigroup/spack/admin/mnp.sh]

To set up the initial directory and build some of the base packages do the following. Note that this assumes an Apptainer image exists in the standard location for the platform version you are setting up (see [[#Apptainer|Apptainer section above]] for details).

In this example we assume we are building for a new platform named "almalinux:9.2-20230718".

# newgrp spack   # start new shell with spack as the default group
# cd /scigroup/spack/admin
# cp make_new_platform_centos7.9.sh make_new_platform_almalinux9.2.sh
# <edit the settings at the top of the new make_new_platform_almalinux9.2.sh script>
# ./make_new_platform_almalinux9.2.sh

==== Potential Issues ====
* I had an issue with incompatible compiler and os which was due to the almalinux9.2 compiler gcc11.3.1 being installed with "operating_system: almalinux9" instead of "operating_system: almalinux9.2". I'm not 100% sure where to fix this upstream at the moment so the easy solution is to edit the file ''/home/davidl/.spack/linux/compilers.yaml'' and fix it there.

* When trying to setup centos7.9.2009 I ran into permission denied errors when it started trying to install packages built with the 9.3.0 compiler. This turned out to be as simple as manually creating the directory from inside a singularity shell with:
   mkdir -p ${spack_top}/opt/spack/linux-*-x86_64/gcc-${spack_compiler}

Note that I added the above to the mnp.sh script so it should be done automatically. (I actually haven't tested it yet there may also be a bug in it!)

* The ifarm was unable to reach the website for the ''ca-certificates-mozilla'' package that was a dependency of lmod. The easiest way to handle this was to download it on my ''jana2'' desktop using the ''spack mirror'' command like this:
   ssh jana2
   git clone -c feature.manyFiles=true https://github.com/spack/spack.git
   source spack/share/spack/setup-env.csh
   spack mirror create -D -d spack-mirror-2022-10-28 lmod
   tar czf spack-mirror-2022-10-28.tgz spack-mirror-2022-10-28
   scp spack-mirror-2022-10-28.tgz ifarm1801:/work/epsci
   
   ssh ifarm1801
   newgrp spack
   cd /scigroup/spack
   tar xzf /work/epsci/spack-mirror-2022-10-28.tgz

Then, in a singularity shell on ''ifarm'':
   spack mirror add local_filesystem file:///scigroup/spack/spack-mirror-2022-10-28

At this point re-run the ''./make_new_platform_rocky8.sh'' script and it should install everything for lmod OK.

To add a list of packages to the spack instance, write them to a text file with one line per package specification. An example can be seen here: 
<font size="-1">
''n.b. this can also be done via a [https://spack-tutorial.readthedocs.io/en/latest/tutorial_environments.html yaml file] which may eventually be used to replace this system''
</font>

   [https://github.com/JeffersonLab/epsci-spack/blob/main/admin/jlabce-2.4.txt jlabce-2.4.txt]

# cd /scigroup/spack/admin
# cp add_to_platform_centos7.sh add_to_platform_rocky8.sh
# <edit the settings at the top of the new add_to_platform_rocky8.sh script>
# ./add_to_platform_rocky8.sh jlabce-2.4.txt

=== Setting up the module system (LMOD) ===

The [https://github.com/JeffersonLab/epsci-spack/blob/main/admin/mnp.sh mnp.sh] script should already set up the LMOD system configuration when a new platform is created. This section documents some of what was done and why.

We would like most users to be be able to interact with the spack packages using the standard "module load" command. Spack has nice support for this though there are options for how it is setup and we'd like to be consistent across supported platforms.

First off, we use the LMOD system as it supports hierarchical module files. This allows us to configure the system so that when a specific compiler is loaded, only packages corresponding to that compiler are listed. This should make it easier on the user to navigate and to avoid loading incompatible packages. We also configure it to present packages using the {package}/{version} naming scheme. This is what is used by /apps on the CUE which will make the spack packages integrate more seamlessly with those.

==== Modules configuration file ====

The ''${SPACK_ROOT}/etc/spack/modules.yaml'' configuration file must be created and have the following content added. This is mostly based on an example given in the [https://spack-tutorial.readthedocs.io/en/latest/tutorial_modules.html spack documentation] under "Hierarchical Module Files". Descriptions of the settings are given below. 

<div class="toccolours mw-collapsible mw-collapsed">
EXAMPLE modules.yaml. (Click "Expand" to the right to see the example -->):

<div class="mw-collapsible-content">
  modules:
    enable::
      - lmod
    lmod:
      core_compilers:
        - 'gcc@4.8.5'
      hierarchy:
        - mpi
      hash_length: 0
      whitelist:
        - gcc
      blacklist:
        - '%gcc@4.8.5'
        - 'arch=linux-centos7-zen2'
      all:
        filter:
          environment_blacklist:
            - "C_INCLUDE_PATH"
            - "CPLUS_INCLUDE_PATH"
            - "LIBRARY_PATH"
        environment:
          set:
            '{name}_ROOT': '{prefix}'
      projections:
        all:          '{name}/{version}'
        ^lapack:      '{name}/{version}-{^lapack.name}'
</div>
</div>

* The core_compilers section should list the system compiler as the default.
* hash_length: 0 removes the spack hash from package names
* whitelist ensures all gcc compilers are available. (Once one of those is loaded, other packages will appear.)
* blacklist excludes packages built with the default system compiler (n.b. whitelist overrides this so other compilers will still be listed)
** the ''arch='' blacklist line excludes packages built specifically with the zen2 microcode instead of generic x86_64. Those packages were actually built by mistake and may be removed altogether. This is a nice way though of obscuring them from view.
* The environment_blacklist filter was just copied from the spack example in the documentation. We may want to remove it. I did not recall build systems using those variables so just left it in.
* The environment: set: section adds an environment variable for every package that is {package}_ROOT so the root directory of the package can be easily obtained, even if the package itself does not define such a variable.
* The projections section defines the module naming scheme. The line for ''lapack'' was left in from the spack tutorial example.

== Building a new package ==

We anticipate getting user requests for new packages. Building packages that already have a spack configuration should be fairly straight-forward. There are a couple of questions to answer before you do it though are:

# Is this package something we should be supporting via spack?
# Should this be part of a spack Environment?
# What compilers/platforms should this be built for?

Once you have answers for these then you can proceed.

The best way to handle this is to use the appropriate ''[https://github.com/JeffersonLab/epsci-spack/blob/main/admin/add_to_platform_centos7.sh add_to_platform_X.sh]'' script with the exact package specification written in a text file. If it is not being added to an existing spack Environment then it should be added to the ''misc_packages.txt'' file for archival purposes. Make sure to commit any changes to github.

Details on this can be seen at the bottom of the [[#add_to_platform|section above on adding packages]] to a new platform.

=== Building a new package manually ===
If you have trouble using an ''add_to_platform_X.sh'' script then you can build the package manually. This is useful if you need to debug why a package is failing to build. If you decide you need to build manually you can do so by launching a singularity shell for the appropriate platform and running the ''spack install'' command. To make the command for launching the singularity container with all of the correct volume bindings, admin scripts are available:

   > ssh ifarm1901
   > /scigroup/spack/admin/singshell_centos7.sh
   source /cvmfs/oasis.opensciencegrid.org/jlab/epsci/centos/7.7.1908/share/spack/setup-env.sh
   Singularity>

The last line indicates you are now running in a singularity shell. The line before it that starts with ''"source /cvmfs/..."'' SHOULD BE COPIED AND EXECUTED WITHIN THE SHELL. This is important since the setup-env.sh script is not run automatically when the singularity shell is created. Sourcing it is necessary to setup your environment for working with the spack instance.

continuing the example ...

   Singularity> source /cvmfs/oasis.opensciencegrid.org/jlab/epsci/centos/7.7.1908/share/spack/setup-env.sh
   Singularity> spack install -j16 clhep@2.4.1.3 %gcc@9.3.0 target=x86_64 

The above will build the clhep package version 2.4.1.3 using the GCC 9.3.0 compiler and make the binaries for the generic x86_64 target. Note that by default spack will build with microcode for the specific processor in use on the machine on which you are compiling. Adding the ''target=x86_64'' ensures all packages are built the same regardless of specifics of the CPU.

It should also be noted that, if there are dependencies for the package you are building the specific versions should be given in the package specification. The syntax for this is beyond the scope of this document and the spack documentation should be consulted for details.

= Updating the buildcache aka mirror =

The build cache is only useful if someone is trying to run [[#untethered|untethered]]. Individual packages (tarballs) can be made from existing spack package builds with the ''buildcache create'' command. It is also possible to generate buildcache packages from all packages in a repository or (probably) an Environment with a single command. Look into the spack help for details. Once the buildcache packages are built, you need to rebuild the index. Here are some specific commands:

# spack buildcache create -r -a -u -d . zlib%gcc@10.2.1
# spack buildcache update-index -k -d /scigroup/spack/mirror

== Misc. Notes ==
Here are some miscellaneous notes to catch useful tidbits not covered in the previous sections.

=== Mac OS X + Docker ===
The default disk format for Mac OS X is non-case-sensitive. It automatically translates file and directory names to give the illusion that it is case sensitive. This works fine except when you have two files in the same directory whose name only differs by case. This becomes an issue if you are building spack packages for Linux using Docker and are doing so in a directory from the local disk (bound in the Docker container). I saw this with the ncurses package failing with errors related to '''E/E_TERM''' and '''A/APPLE_TERM''' (I may not be remembering the exact file names correctly).

One work-around is to create a disk image using Disk Utility and choose the format to be ''"Mac OS Extended (Case-sensitive, Journaled)"''. Mount the disk image and bind that to the docker container. This will give you a case sensitive persistent disk (i.e. survives after the container exits).

If you do not care about persistence, then just build in a directory in the Docker container's temporary file system. You can always save to a buildcache from there and copy just the buildcache file out of the container.