<!--#include virtual="header.txt"-->

<h1>Containers Guide</h1>

<h2 id="contents">Contents<a class="slurm_link" href="#contents"></a></h2>
<ul>
<li><a href="#overview">Overview</a></li>
<li><a href="#limitations">Known limitations</a></li>
<li><a href="#prereq">Prerequisites</a></li>
<li><a href="#software">Required software</a></li>
<li><a href="#example">Example configurations for various OCI Runtimes</a></li>
<li><a href="#testing">Testing OCI runtime outside of Slurm</a></li>
<li><a href="#request">Requesting container jobs or steps</a></li>
<li><a href="#docker-scrun">Integration with Rootless Docker</a></li>
<li><a href="#podman-scrun">Integration with Podman</a></li>
<li><a href="#bundle">OCI Container bundle</a></li>
<li><a href="#ex-ompi5-pmix4">Example OpenMPI v5 + PMIx v4 container</a></li>
<li><a href="#plugin">Container support via Plugin</a>
<ul>
<li><a href="#shifter">Shifter</a></li>
<li><a href="#enroot1">ENROOT and Pyxis</a></li>
<li><a href="#sarus">Sarus</a></li>
</ul></li>
</ul>

<h2 id="overview">Overview<a class="slurm_link" href="#overview"></a></h2>
<p>Containers are being adopted in HPC workloads.
Containers rely on existing kernel features to allow greater user control over
what applications see and can interact with at any given time. For HPC
Workloads, these are usually restricted to the
<a href="http://man7.org/linux/man-pages/man7/mount_namespaces.7.html">mount namespace</a>.
Slurm natively supports the requesting of unprivileged OCI Containers for jobs
and steps.</p>

<p>Setting up containers requires several steps:
<ol>
<li>Set up the <a href="#prereq">kernel</a> and a
    <a href="#software">container runtime</a>.</li>
<li>Deploy a suitable <a href="oci.conf.html">oci.conf</a> file accessible to
    the compute nodes (<a href="#example">examples below</a>).</li>
<li>Restart or reconfigure slurmd on the compute nodes.</li>
<li>Generate <a href="#bundle">OCI bundles</a> for containers that are needed
    and place them on the compute nodes.</li>
<li>Verify that you can <a href="#testing">run containers directly</a> through
    the chosen OCI runtime.</li>
<li>Verify that you can <a href="#request">request a container</a> through
    Slurm.</li>
</ol>
</p>

<h2 id="limitations">Known limitations
<a class="slurm_link" href="#limitations"></a>
</h2>
<p>The following is a list of known limitations of the Slurm OCI container
implementation.</p>

<ul>
<li>All containers must run under unprivileged (i.e. rootless) invocation.
All commands are called by Slurm as the user with no special
permissions.</li>

<li>Custom container networks are not supported. All containers should work
with the <a href="https://docs.docker.com/network/host/">"host"
network</a>.</li>

<li>Slurm will not transfer the OCI container bundle to the execution
nodes. The bundle must already exist on the requested path on the
execution node.</li>

<li>Containers are limited by the OCI runtime used. If the runtime does not
support a certain feature, then that feature will not work for any job
using a container.</li>

<li>oci.conf must be configured on the execution node for the job, otherwise the
requested container will be ignored by Slurm (but can be used by the
job or any given plugin).</li>
</ul>

<h2 id="prereq">Prerequisites<a class="slurm_link" href="#prereq"></a></h2>
<p>The host kernel must be configured to allow user land containers:</p>
<pre>
sudo sysctl -w kernel.unprivileged_userns_clone=1
sudo sysctl -w kernel.apparmor_restrict_unprivileged_unconfined=0
sudo sysctl -w kernel.apparmor_restrict_unprivileged_userns=0
</pre>

<p>Docker also provides a tool to verify the kernel configuration:
<pre>$ dockerd-rootless-setuptool.sh check --force
[INFO] Requirements are satisfied</pre>
</p>

<h2 id="software">Required software:
<a class="slurm_link" href="#software"></a>
</h2>
<ul>
<li>Fully functional
<a href="https://github.com/opencontainers/runtime-spec/blob/master/runtime.md">
OCI runtime</a>. It needs to be able to run outside of Slurm first.</li>

<li>Fully functional OCI bundle generation tools. Slurm requires OCI
Container compliant bundles for jobs.</li>
</ul>

<h2 id="example">Example configurations for various OCI Runtimes
<a class="slurm_link" href="#example"></a>
</h2>
<p>
The <a href="https://github.com/opencontainers/runtime-spec">OCI Runtime
Specification</a> provides requirements for all compliant runtimes but
does <b>not</b> expressly provide requirements on how runtimes will use
arguments. In order to support as many runtimes as possible, Slurm provides
pattern replacement for commands issued for each OCI runtime operation.
This will allow a site to edit how the OCI runtimes are called as needed to
ensure compatibility.
</p>
<p>
For <i>runc</i> and <i>crun</i>, there are two sets of examples provided.
The OCI runtime specification only provides the <i>start</i> and <i>create</i>
operations sequence, but these runtimes provides a much more efficient <i>run</i>
operation. Sites are strongly encouraged to use the <i>run</i> operation
(if provided) as the <i>start</i> and <i>create</i> operations require that
Slurm poll the OCI runtime to know when the containers have completed execution.
While Slurm attempts to be as efficient as possible with polling, it will
result in a thread using CPU time inside of the job and slower response of
Slurm to catch when container execution is complete.
</p>
<p>
The examples provided have been tested to work but are only suggestions. Sites
are expected to ensure that the resultant root directory used will be secure
from cross user viewing and modifications. The examples provided point to
"/run/user/%U" where %U will be replaced with the numeric user id. Systemd
manages "/run/user/" (independently of Slurm) and will likely need additional
configuration to ensure the directories exist on compute nodes when the users
will not log in to the nodes directly. This configuration is generally achieved
by calling
<a href="https://www.freedesktop.org/software/systemd/man/latest/loginctl.html#enable-linger%20USER%E2%80%A6">
loginctl to enable lingering sessions</a>. Be aware that the directory in this
example will be cleaned up by systemd once the user session ends on the node.
</p>

<h3 id="runc_create_start">oci.conf example for runc using create/start:
<a class="slurm_link" href="#runc_create_start"></a></h3>
<p>
<pre>
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeQuery="runc --rootless=true --root=/run/user/%U/ state %n.%u.%j.%s.%t"
RunTimeCreate="runc --rootless=true --root=/run/user/%U/ create %n.%u.%j.%s.%t -b %b"
RunTimeStart="runc --rootless=true --root=/run/user/%U/ start %n.%u.%j.%s.%t"
RunTimeKill="runc --rootless=true --root=/run/user/%U/ kill -a %n.%u.%j.%s.%t"
RunTimeDelete="runc --rootless=true --root=/run/user/%U/ delete --force %n.%u.%j.%s.%t"
</pre>
</p>

<h3 id="runc_run">oci.conf example for runc using run (recommended over using
create/start):<a class="slurm_link" href="#runc_run"></a></h3>
<p>
<pre>
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeQuery="runc --rootless=true --root=/run/user/%U/ state %n.%u.%j.%s.%t"
RunTimeKill="runc --rootless=true --root=/run/user/%U/ kill -a %n.%u.%j.%s.%t"
RunTimeDelete="runc --rootless=true --root=/run/user/%U/ delete --force %n.%u.%j.%s.%t"
RunTimeRun="runc --rootless=true --root=/run/user/%U/ run %n.%u.%j.%s.%t -b %b"
</pre>
</p>

<h3 id="crun_create_start">oci.conf example for crun using create/start:
<a class="slurm_link" href="#crun_create_start"></a></h3>
<p>
<pre>
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeQuery="crun --rootless=true --root=/run/user/%U/ state %n.%u.%j.%s.%t"
RunTimeKill="crun --rootless=true --root=/run/user/%U/ kill -a %n.%u.%j.%s.%t"
RunTimeDelete="crun --rootless=true --root=/run/user/%U/ delete --force %n.%u.%j.%s.%t"
RunTimeCreate="crun --rootless=true --root=/run/user/%U/ create --bundle %b %n.%u.%j.%s.%t"
RunTimeStart="crun --rootless=true --root=/run/user/%U/ start %n.%u.%j.%s.%t"
</pre>
</p>

<h3 id="crun_run">oci.conf example for crun using run (recommended over using
create/start):<a class="slurm_link" href="#crun_run"></a></h3>
<p>
<pre>
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeQuery="crun --rootless=true --root=/run/user/%U/ state %n.%u.%j.%s.%t"
RunTimeKill="crun --rootless=true --root=/run/user/%U/ kill -a %n.%u.%j.%s.%t"
RunTimeDelete="crun --rootless=true --root=/run/user/%U/ delete --force %n.%u.%j.%s.%t"
RunTimeRun="crun --rootless=true --root=/run/user/%U/ run --bundle %b %n.%u.%j.%s.%t"
</pre>
</p>

<h3 id="nvidia_create_start">
oci.conf example for nvidia-container-runtime using create/start:
<a class="slurm_link" href="#nvidia_create_start"></a></h3>
<p>
<pre>
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeQuery="nvidia-container-runtime --rootless=true --root=/run/user/%U/ state %n.%u.%j.%s.%t"
RunTimeCreate="nvidia-container-runtime --rootless=true --root=/run/user/%U/ create %n.%u.%j.%s.%t -b %b"
RunTimeStart="nvidia-container-runtime --rootless=true --root=/run/user/%U/ start %n.%u.%j.%s.%t"
RunTimeKill="nvidia-container-runtime --rootless=true --root=/run/user/%U/ kill -a %n.%u.%j.%s.%t"
RunTimeDelete="nvidia-container-runtime --rootless=true --root=/run/user/%U/ delete --force %n.%u.%j.%s.%t"
</pre>
</p>

<h3 id="nvidia_run">
oci.conf example for nvidia-container-runtime using run (recommended over using
create/start):<a class="slurm_link" href="#nvidia_run"></a></h3>
<p>
<pre>
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeQuery="nvidia-container-runtime --rootless=true --root=/run/user/%U/ state %n.%u.%j.%s.%t"
RunTimeKill="nvidia-container-runtime --rootless=true --root=/run/user/%U/ kill -a %n.%u.%j.%s.%t"
RunTimeDelete="nvidia-container-runtime --rootless=true --root=/run/user/%U/ delete --force %n.%u.%j.%s.%t"
RunTimeRun="nvidia-container-runtime --rootless=true --root=/run/user/%U/ run %n.%u.%j.%s.%t -b %b"
</pre>
</p>

<h3 id="singularity_native">oci.conf example for
<a href="https://docs.sylabs.io/guides/4.1/admin-guide/installation.html">
Singularity v4.1.3</a> using native runtime:
<a class="slurm_link" href="#singularity_native"></a></h3>
<p>
<pre>
IgnoreFileConfigJson=true
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeRun="singularity exec --userns %r %@"
RunTimeKill="kill -s SIGTERM %p"
RunTimeDelete="kill -s SIGKILL %p"
</pre>
</p>

<h3 id="singularity_oci">oci.conf example for
<a href="https://docs.sylabs.io/guides/4.0/admin-guide/installation.html">
Singularity v4.0.2</a> in OCI mode:
<a class="slurm_link" href="#singularity_oci"></a></h3>
<p>
Singularity v4.x requires setuid mode for OCI support.
<pre>
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeQuery="sudo singularity oci state %n.%u.%j.%s.%t"
RunTimeRun="sudo singularity oci run --bundle %b %n.%u.%j.%s.%t"
RunTimeKill="sudo singularity oci kill %n.%u.%j.%s.%t"
RunTimeDelete="sudo singularity oci delete %n.%u.%j.%s.%t"
</pre>
</p>

<p><b>WARNING</b>: Singularity (v4.0.2) requires <i>sudo</i> or setuid binaries
for OCI support, which is a security risk since the user is able to modify
these calls. This example is only provided for testing purposes.</p>
<p><b>WARNING</b>:
<a href="https://groups.google.com/a/lbl.gov/g/singularity/c/vUMUkMlrpQc/m/gIsEiiP7AwAJ">
Upstream singularity development</a> of the OCI interface appears to have
ceased and sites should use the <a href="#singularity_native">user
namespace support</a> instead.</p>

<h3 id="singularity_hpcng">oci.conf example for hpcng Singularity v3.8.0:
<a class="slurm_link" href="#singularity_hpcng"></a></h3>
<p>
<pre>
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeQuery="sudo singularity oci state %n.%u.%j.%s.%t"
RunTimeCreate="sudo singularity oci create --bundle %b %n.%u.%j.%s.%t"
RunTimeStart="sudo singularity oci start %n.%u.%j.%s.%t"
RunTimeKill="sudo singularity oci kill %n.%u.%j.%s.%t"
RunTimeDelete="sudo singularity oci delete %n.%u.%j.%s.%t
</pre>
</p>

<p><b>WARNING</b>: Singularity (v3.8.0) requires <i>sudo</i> or setuid binaries
for OCI support, which is a security risk since the user is able to modify
these calls. This example is only provided for testing purposes.</p>
<p><b>WARNING</b>:
<a href="https://groups.google.com/a/lbl.gov/g/singularity/c/vUMUkMlrpQc/m/gIsEiiP7AwAJ">
Upstream singularity development</a> of the OCI interface appears to have
ceased and sites should use the <a href="#singularity_native">user
namespace support</a> instead.</p>

<h3 id="charliecloud">oci.conf example for
<a href="https://github.com/hpc/charliecloud">Charliecloud</a> (v0.30)
<a class="slurm_link" href="#charliecloud"></a></h3>
<p>
<pre>
IgnoreFileConfigJson=true
CreateEnvFile=newline
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeRun="env -i PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin/:/sbin/ USER=$(whoami) HOME=/home/$(whoami)/ ch-run -w --bind /etc/group:/etc/group --bind /etc/passwd:/etc/passwd --bind /etc/slurm:/etc/slurm --bind %m:/var/run/slurm/ --bind /var/run/munge/:/var/run/munge/ --set-env=%e --no-passwd %r -- %@"
RunTimeKill="kill -s SIGTERM %p"
RunTimeDelete="kill -s SIGKILL %p"
</pre>
</p>

<h3 id="enroot">oci.conf example for
<a href="https://github.com/NVIDIA/enroot">Enroot</a> (3.3.0)
<a class="slurm_link" href="#enroot"></a></h3>
<p>
<pre>
IgnoreFileConfigJson=true
CreateEnvFile=newline
EnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeEnvExclude="^(SLURM_CONF|SLURM_CONF_SERVER)="
RunTimeRun="/usr/local/bin/enroot-start-wrapper %b %m %e -- %@"
RunTimeKill="kill -s SIGINT %p"
RunTimeDelete="kill -s SIGTERM %p"
</pre>
</p>

<p>/usr/local/bin/enroot-start-wrapper:
<pre>
#!/bin/bash
BUNDLE="$1"
SPOOLDIR="$2"
ENVFILE="$3"
shift 4
IMAGE=

export USER=$(whoami)
export HOME="$BUNDLE/"
export TERM
export ENROOT_SQUASH_OPTIONS='-comp gzip -noD'
export ENROOT_ALLOW_SUPERUSER=n
export ENROOT_MOUNT_HOME=y
export ENROOT_REMAP_ROOT=y
export ENROOT_ROOTFS_WRITABLE=y
export ENROOT_LOGIN_SHELL=n
export ENROOT_TRANSFER_RETRIES=2
export ENROOT_CACHE_PATH="$SPOOLDIR/"
export ENROOT_DATA_PATH="$SPOOLDIR/"
export ENROOT_TEMP_PATH="$SPOOLDIR/"
export ENROOT_ENVIRON="$ENVFILE"

if [ ! -f "$BUNDLE" ]
then
        IMAGE="$SPOOLDIR/container.sqsh"
        enroot import -o "$IMAGE" -- "$BUNDLE" && \
        enroot create "$IMAGE"
        CONTAINER="container"
else
        CONTAINER="$BUNDLE"
fi

enroot start -- "$CONTAINER" "$@"
rc=$?

[ $IMAGE ] && unlink $IMAGE

exit $rc
</pre>
</p>

<h3 id="multiple-runtimes">Handling multiple runtimes
<a class="slurm_link" href="#multiple-runtimes"></a>
</h3>

<p>If you wish to accommodate multiple runtimes in your environment,
it is possible to do so with a bit of extra setup. This section outlines one
possible way to do so:</p>

<ol>
<li>Create a generic oci.conf that calls a wrapper script
<pre>
IgnoreFileConfigJson=true
RunTimeRun="/opt/slurm-oci/run %b %m %u %U %n %j %s %t %@"
RunTimeKill="kill -s SIGTERM %p"
RunTimeDelete="kill -s SIGKILL %p"
</pre>
</li>
<li>Create the wrapper script to check for user-specific run configuration
(e.g., /opt/slurm-oci/run)
<pre>
#!/bin/bash
if [[ -e ~/.slurm-oci-run ]]; then
	~/.slurm-oci-run "$@"
else
	/opt/slurm-oci/slurm-oci-run-default "$@"
fi
</pre>
</li>
<li>Create a generic run configuration to use as the default
(e.g., /opt/slurm-oci/slurm-oci-run-default)
<pre>
#!/bin/bash --login
# Parse
CONTAINER="$1"
SPOOL_DIR="$2"
USER_NAME="$3"
USER_ID="$4"
NODE_NAME="$5"
JOB_ID="$6"
STEP_ID="$7"
TASK_ID="$8"
shift 8 # subsequent arguments are the command to run in the container
# Run
apptainer run --bind /var/spool --containall "$CONTAINER" "$@"
</pre>
</li>
<li>Add executable permissions to both scripts
<pre>chmod +x /opt/slurm-oci/run /opt/slurm-oci/slurm-oci-run-default</pre>
</li>
</ol>

<p>Once this is done, users may create a script at '~/.slurm-oci-run' if
they wish to customize the container run process, such as using a different
container runtime. Users should model this file after the default
'/opt/slurm-oci/slurm-oci-run-default'</p>

<h2 id="testing">Testing OCI runtime outside of Slurm
<a class="slurm_link" href="#testing"></a>
</h2>
<p>Slurm calls the OCI runtime directly in the job step. If it fails,
then the job will also fail.</p>
<ul>
<li>Go to the directory containing the OCI Container bundle:
<pre>cd $ABS_PATH_TO_BUNDLE</pre></li>

<li>Execute OCI Container runtime (You can find a few examples on how to build
a bundle <a href="#bundle">below</a>):
<pre>$OCIRunTime $ARGS create test --bundle $PATH_TO_BUNDLE</pre>
<pre>$OCIRunTime $ARGS start test</pre>
<pre>$OCIRunTime $ARGS kill test</pre>
<pre>$OCIRunTime $ARGS delete test</pre>
If these commands succeed, then the OCI runtime is correctly
configured and can be tested in Slurm.
</li>
</ul>

<h2 id="request">Requesting container jobs or steps
<a class="slurm_link" href="#request"></a>
</h2>
<p>
<i>salloc</i>, <i>srun</i> and <i>sbatch</i> (in Slurm 21.08+) have the
'--container' argument, which can be used to request container runtime
execution. The requested job container will not be inherited by the steps
called, excluding the batch and interactive steps.
</p>

<ul>
<li>Batch step inside of container:
<pre>sbatch --container $ABS_PATH_TO_BUNDLE --wrap 'bash -c "cat /etc/*rel*"'
</pre></li>

<li>Batch job with step 0 inside of container:
<pre>
sbatch --wrap 'srun bash -c "--container $ABS_PATH_TO_BUNDLE cat /etc/*rel*"'
</pre></li>

<li>Interactive step inside of container:
<pre>salloc --container $ABS_PATH_TO_BUNDLE bash -c "cat /etc/*rel*"</pre></li>

<li>Interactive job step 0 inside of container:
<pre>salloc srun --container $ABS_PATH_TO_BUNDLE bash -c "cat /etc/*rel*"
</pre></li>

<li>Job with step 0 inside of container:
<pre>srun --container $ABS_PATH_TO_BUNDLE bash -c "cat /etc/*rel*"</pre></li>

<li>Job with step 1 inside of container:
<pre>srun srun --container $ABS_PATH_TO_BUNDLE bash -c "cat /etc/*rel*"
</pre></li>
</ul>

<p><b>NOTE</b>: Commands run with the <code>--container</code> flag are resolved
through PATH <i>before</i> they are sent to the container. If the container has
a unique file structure, it may be necessary to give the full path to the
command or specify <code>--export=NONE</code> to have the container define the
PATH to be used:
<pre>srun --container $ABS_PATH_TO_BUNDLE --export=NONE bash -c "cat /etc/*rel*"
</pre></p>

<h2 id="docker-scrun">Integration with Rootless Docker (Docker Engine v20.10+ & Slurm-23.02+)
<a class="slurm_link" href="#docker-scrun"></a>
</h2>
<p>Slurm's <a href="scrun.html">scrun</a> can be directly integrated with <a
href="https://docs.docker.com/engine/security/rootless/">Rootless Docker</a> to
run containers as jobs. No special user permissions are required and <b>should
not</b> be granted to use this functionality.</p>
<h3>Prerequisites</h3>
<ol>
<li><a href="slurm.conf.html">slurm.conf</a> must be configured to use Munge
authentication.<pre>AuthType=auth/munge</pre></li>
<li><a href="scrun.html#SECTION_Example-<B>scrun.lua</B>-scripts">scrun.lua</a>
must be configured for site storage configuration.</li>
<li><a href="https://docs.docker.com/engine/security/rootless/#routing-ping-packets">
	Configure kernel to allow pings</a></li>
<li><a href="https://docs.docker.com/engine/security/rootless/#exposing-privileged-ports">
	Configure rootless dockerd to allow listening on privileged ports
	</a></li>
<li><a href="scrun.html#SECTION_Example-%3CB%3Escrun.lua%3C/B%3E-scripts">
	scrun.lua</a> must be present on any node where scrun may be run. The
	example should be sufficient for most environments but paths should be
	modified to match available local storage.</li>
<li><a href="oci.conf.html">oci.conf</a> must be present on any node where any
	container job may be run. Example configurations for
	<a href="https://slurm.schedmd.com/containers.html#example">
	known OCI runtimes</a> are provided above. Examples may require
	paths to be correct to installation locations.</li>
</ol>
<h3>Limitations</h3>
<ol>
<li>JWT authentication is not supported.</li>
<li>Docker container building is not currently functional pending merge of
<a href="https://github.com/moby/moby/pull/41442"> Docker pull request</a>.</li>
<li>Docker does <b>not</b> expose configuration options to disable security
options needed to run jobs. This requires that all calls to docker provide the
following command line arguments.  This can be done via shell variable, an
alias, wrapper function, or wrapper script:
<pre>--security-opt label:disable --security-opt seccomp=unconfined --security-opt apparmor=unconfined --net=none</pre>
Docker's builtin security functionality is not required (or wanted) for
containers being run by Slurm.  Docker is only acting as a container image
lifecycle manager. The containers will be executed remotely via Slurm following
the existing security configuration in Slurm outside of unprivileged user
control.</li>
<li>All containers must use the
<a href="https://docs.docker.com/network/drivers/none/">"none" networking driver
</a>. Attempting to use bridge, overlay, host, ipvlan, or macvlan can result in
scrun being isolated from the network and not being able to communicate with
the Slurm controller. The container is run by Slurm on the compute nodes which
makes having Docker setup a network isolation layer ineffective for the
container.</li>
<li><code>docker exec</code> command is not supported.</li>
<li><code>docker swarm</code> command is not supported.</li>
<li><code>docker compose</code>/<code>docker-compose</code> command is not
	supported.</li>
<li><code>docker pause</code> command is not supported.</li>
<li><code>docker unpause</code> command is not supported.</li>
<li><code>docker swarm</code> command is not supported.</li>
<li>All <code>docker</code> commands are not supported inside of containers.</li>
<li><a href="https://docs.docker.com/reference/api/engine/">Docker API</a> is
	not supported inside of containers.</li>
</ol>

<h3>Setup procedure</h3>
<ol>
<li><a href="https://docs.docker.com/engine/security/rootless/"> Install and
configure Rootless Docker</a><br> Rootless Docker must be fully operational and
able to run containers before continuing.</li>
<li>
Setup environment for all docker calls:
<pre>export DOCKER_HOST=unix://$XDG_RUNTIME_DIR/docker.sock</pre>
All commands following this will expect this environment variable to be set.</li>
<li>Stop rootless docker: <pre>systemctl --user stop docker</pre></li>
<li>Configure Docker to call scrun instead of the default OCI runtime.
<!-- Docker does not document: --runtime= argument -->
<ul>
<li>To configure for all users: <pre>/etc/docker/daemon.json</pre></li>
<li>To configure per user: <pre>~/.config/docker/daemon.json</pre></li>
</ul>
Set the following fields to configure Docker:
<pre>{
    "experimental": true,
    "iptables": false,
    "bridge": "none",
    "no-new-privileges": true,
    "rootless": true,
    "selinux-enabled": false,
    "default-runtime": "slurm",
    "runtimes": {
        "slurm": {
            "path": "/usr/local/bin/scrun"
        }
    },
    "data-root": "/run/user/${USER_ID}/docker/",
    "exec-root": "/run/user/${USER_ID}/docker-exec/"
}</pre>
Correct path to scrun as if installation prefix was configured. Replace
${USER_ID} with numeric user id or target a different directory with global
write permissions and sticky bit. Rootless docker requires a different root
directory than the system's default to avoid permission errors.</li>
<li>It is strongly suggested that sites consider using inter-node shared
filesystems to store Docker's containers. While it is possible to have a
scrun.lua script to push and pull images for each deployment, there can be a
massive performance penalty.  Using a shared filesystem will avoid moving these
files around.<br>Possible configuration additions to daemon.json to use a
shared filesystem with <a
href="https://docs.docker.com/storage/storagedriver/vfs-driver/"> vfs storage
driver</a>:
<pre>{
  "storage-driver": "vfs",
  "data-root": "/path/to/shared/filesystem/user_name/data/",
  "exec-root": "/path/to/shared/filesystem/user_name/exec/",
}</pre>
Any node expected to be able to run containers from Docker must have ability to
at least read the filesystem used. Full write privileges are suggested and will
be required if changes to the container filesystem are desired.</li>

<li>Configure dockerd to not setup network namespace, which will break scrun's
	ability to talk to the Slurm controller.
<!-- Docker does not document: --runtime= argument -->
<ul>
<li>To configure for all users:
<pre>/etc/systemd/user/docker.service.d/override.conf</pre></li>
<li>To configure per user:
<pre>~/.config/systemd/user/docker.service.d/override.conf</pre></li>
</ul>
<pre>
[Service]
Environment="DOCKERD_ROOTLESS_ROOTLESSKIT_PORT_DRIVER=none"
Environment="DOCKERD_ROOTLESS_ROOTLESSKIT_NET=host"
</pre>
</li>
<li>Reload docker's service unit in systemd:
<pre>systemctl --user daemon-reload</pre></li>
<li>Start rootless docker: <pre>systemctl --user start docker</pre></li>
<li>Verify Docker is using scrun:
<pre>export DOCKER_SECURITY="--security-opt label=disable --security-opt seccomp=unconfined  --security-opt apparmor=unconfined --net=none"
docker run $DOCKER_SECURITY hello-world
docker run $DOCKER_SECURITY alpine /bin/printenv SLURM_JOB_ID
docker run $DOCKER_SECURITY alpine /bin/hostname
docker run $DOCKER_SECURITY -e SCRUN_JOB_NUM_NODES=10 alpine /bin/hostname</pre>
</li>
</ol>

<h2 id="podman-scrun">Integration with Podman (Slurm-23.02+)
<a class="slurm_link" href="#podman-scrun"></a>
</h2>
<p>
Slurm's <a href="scrun.html">scrun</a> can be directly integrated with
<a href="https://podman.io/">Podman</a>
to run containers as jobs. No special user permissions are required and
<b>should not</b> be granted to use this functionality.
</p>
<h3>Prerequisites</h3>
<ol>
<li>Slurm must be fully configured and running on host running podman.</li>
<li><a href="slurm.conf.html">slurm.conf</a> must be configured to use Munge
authentication.<pre>AuthType=auth/munge</pre></li>
<li><a href="scrun.html">scrun.lua</a> must be configured for site storage
configuration.</li>
<li><a href="scrun.html#SECTION_Example-%3CB%3Escrun.lua%3C/B%3E-scripts">
	scrun.lua</a> must be present on any node where scrun may be run. The
	example should be sufficient for most environments but paths should be
	modified to match available local storage.</li>
<li><a href="oci.conf.html">oci.conf</a>
	must be present on any node where any container job may be run.
	Example configurations for
	<a href="https://slurm.schedmd.com/containers.html#example">
	known OCI runtimes</a> are provided above. Examples may require
	paths to be correct to installation locations.</li>
</ol>
</ol>
<h3>Limitations</h3>
<ol>
<li>JWT authentication is not supported.</li>
<li>All containers must use
<a href="https://github.com/containers/podman/blob/main/docs/tutorials/basic_networking.md">
host networking</a></li>
<li><code>podman exec</code> command is not supported.</li>
<li><code>podman-compose</code> command is not supported, due to only being
	partially implemented. Some compositions may work but each container
	may be run on different nodes. The network for all containers must be
	the <code>network_mode: host</code> device.</li>
<li><code>podman kube</code> command is not supported.</li>
<li><code>podman pod</code> command is not supported.</li>
<li><code>podman farm</code> command is not supported.</li>
<li>All <code>podman</code> commands are not supported inside of containers.</li>
<li>Podman REST API is not supported inside of containers.</li>
</ol>

<h3>Setup procedure</h3>
<ol>
<li><a href="https://podman.io/docs/installation">Install Podman</li>
<li><a href="https://github.com/containers/podman/blob/main/docs/tutorials/rootless_tutorial.md">
Configure rootless Podman</a></li>
<li>Verify rootless podman is configured
	<pre>$ podman info --format '{{.Host.Security.Rootless}}'
true</pre></li>
<li>Verify rootless Podman is fully functional before adding Slurm support:
<ul>
	<li>The value printed by the following commands should be the same:
	<pre>$ id
$ podman run --userns keep-id alpine id</pre>
	<pre>$ sudo id
$ podman run --userns nomap alpine id</pre></li>
</ul></li>
<li>
Configure Podman to call scrun instead of the <a
href="https://github.com/opencontainers/runtime-spec"> default OCI runtime</a>.
See <a href="https://github.com/containers/common/blob/main/docs/containers.conf.5.md">
upstream documentation</a> for details on configuration locations and loading
order for containers.conf.
<ul>
<li>To configure for all users:
<code>/etc/containers/containers.conf</code></li>
<li>To configure per user:
<code>$XDG_CONFIG_HOME/containers/containers.conf</code>
or
<code>~/.config/containers/containers.conf</code>
(if <code>$XDG_CONFIG_HOME</code> is not defined).</li>
</ul>
Set the following configuration parameters to configure Podman's containers.conf:
<pre>[containers]
apparmor_profile = "unconfined"
cgroupns = "host"
cgroups = "enabled"
default_sysctls = []
label = false
netns = "host"
no_hosts = true
pidns = "host"
utsns = "host"
userns = "host"
log_driver = "journald"

[engine]
cgroup_manager = "systemd"
runtime = "slurm"
remote = false

[engine.runtimes]
slurm = [
	"/usr/local/bin/scrun",
	"/usr/bin/scrun"
]</pre>
Correct path to scrun as if installation prefix was configured.</li>
<li>The "cgroup_manager" field will need to be swapped to "cgroupfs" on systems
not running systemd.</li>
<li>It is strongly suggested that sites consider using inter-node shared
filesystems to store Podman's containers. While it is possible to have a
scrun.lua script to push and pull images for each deployment, there can be a
massive performance penalty. Using a shared filesystem will avoid moving these
files around.<br>
<ul>
<li>To configure for all users: <pre>/etc/containers/storage.conf</pre></li>
<li>To configure per user: <pre>$XDG_CONFIG_HOME/containers/storage.conf</pre></li>
</ul>
Possible configuration additions to storage.conf to use a shared filesystem with
<a href="https://docs.podman.io/en/latest/markdown/podman.1.html#storage-driver-value">
vfs storage driver</a>:
<pre>[storage]
driver = "vfs"
runroot = "$HOME/containers"
graphroot = "$HOME/containers"

[storage.options]
pull_options = {use_hard_links = "true", enable_partial_images = "true"}


[storage.options.vfs]
ignore_chown_errors = "true"</pre>
Any node expected to be able to run containers from Podman must have ability to
at least read the filesystem used. Full write privileges are suggested and will
be required if changes to the container filesystem are desired.</li>
<li> Verify Podman is using scrun:
<pre>podman run hello-world
podman run alpine printenv SLURM_JOB_ID
podman run alpine hostname
podman run alpine -e SCRUN_JOB_NUM_NODES=10 hostname
salloc podman run --env-host=true alpine hostname
salloc sh -c 'podman run -e SLURM_JOB_ID=$SLURM_JOB_ID alpine hostname'</pre>
</li>
<li>Optional: Create alias for Docker:
	<pre>alias docker=podman</pre> or
	<pre>alias docker='podman --config=/some/path "$@"'</pre>
</li>
</ol>

<h3>Troubleshooting</h3>
<ul>
<li>Podman runs out of locks:
<pre>$ podman run alpine uptime
Error: allocating lock for new container: allocation failed; exceeded num_locks (2048)
</pre>
<ol>
	<li>Try renumbering:<pre>podman system renumber</pre></li>
	<li>Try resetting all storage:<pre>podman system reset</pre></li>
</ol>
</li>
</ul>

<h2 id="bundle">OCI Container bundle
<a class="slurm_link" href="#bundle"></a>
</h2>
<p>There are multiple ways to generate an OCI Container bundle. The
instructions below are the method we found the easiest. The OCI standard
provides the requirements for any given bundle:
<a href="https://github.com/opencontainers/runtime-spec/blob/master/bundle.md">
Filesystem Bundle</a>
</p>

<p>Here are instructions on how to generate a container using a few
alternative container solutions:</p>

<ul>
    <li>Create an image and prepare it for use with runc:
    <ol>
	<li>
	Use an existing tool to create a filesystem image in /image/rootfs:
	<ul>
	    <li>
		debootstrap:
		<pre>sudo debootstrap stable /image/rootfs http://deb.debian.org/debian/</pre>
	    </li>
	    <li>
		yum:
		<pre>sudo yum --config /etc/yum.conf --installroot=/image/rootfs/ --nogpgcheck --releasever=${CENTOS_RELEASE} -y</pre>
	    </li>
	    <li>
		docker:
		<pre>
mkdir -p ~/oci_images/alpine/rootfs
cd ~/oci_images/
docker pull alpine
docker create --name alpine alpine
docker export alpine | tar -C ~/oci_images/alpine/rootfs -xf -
docker rm alpine</pre>
	    </li>
	</ul>

	<li>
	Configure a bundle for runtime to execute:
	<ul>
	    <li>Use <a href="https://github.com/opencontainers/runc">runc</a>
	    to generate a config.json:
	    <pre>
cd ~/oci_images/alpine
runc --rootless=true spec --rootless</pre>
	    </li>
	    <li>Test running image:</li>
	    <pre>
srun --container ~/oci_images/alpine/ uptime</pre>
	    </li>
	</ul>
    </ol>
    </li>

    <li>Use <a href="https://github.com/opencontainers/umoci">umoci</a>
    and skopeo to generate a full image:
    <pre>
mkdir -p ~/oci_images/
cd ~/oci_images/
skopeo copy docker://alpine:latest oci:alpine:latest
umoci unpack --rootless --image alpine ~/oci_images/alpine
srun --container ~/oci_images/alpine uptime</pre>
    </li>

    <li>
    Use <a href="https://sylabs.io/guides/3.1/user-guide/oci_runtime.html">
    singularity</a> to generate a full image:
    <pre>
mkdir -p ~/oci_images/alpine/
cd ~/oci_images/alpine/
singularity pull alpine
sudo singularity oci mount ~/oci_images/alpine/alpine_latest.sif ~/oci_images/alpine
mv config.json singularity_config.json
runc spec --rootless
srun --container ~/oci_images/alpine/ uptime</pre>
    </li>
</ul>

<h2 id="ex-ompi5-pmix4">Example OpenMPI v5 + PMIx v4 container
<a class="slurm_link" href="#ex-ompi5-pmix4"></a>
</h2>

Minimalist Dockerfile to generate a image with OpenMPI and PMIx to test basic MPI jobs.

<h4>Dockerfile</h4>
<pre>
FROM almalinux:latest
RUN dnf -y update && dnf -y upgrade && dnf install -y epel-release && dnf -y update
RUN dnf -y install make automake gcc gcc-c++ kernel-devel bzip2 python3 wget libevent-devel hwloc-devel

WORKDIR /usr/local/src/
RUN wget --quiet 'https://github.com/openpmix/openpmix/releases/download/v5.0.7/pmix-5.0.7.tar.bz2' -O - | tar --no-same-owner -xvjf -
WORKDIR /usr/local/src/pmix-5.0.7/
RUN ./configure && make -j && make install

WORKDIR /usr/local/src/
RUN wget --quiet --inet4-only 'https://download.open-mpi.org/release/open-mpi/v5.0/openmpi-5.0.7.tar.bz2' -O - | tar --no-same-owner -xvjf -
WORKDIR /usr/local/src/openmpi-5.0.7/
RUN ./configure --disable-pty-support --enable-ipv6 --without-slurm --with-pmix --enable-debug && make -j && make install

WORKDIR /usr/local/src/openmpi-5.0.7/examples
RUN make && cp -v hello_c ring_c connectivity_c spc_example /usr/local/bin
</pre>

<h2 id="plugin">Container support via Plugin
<a class="slurm_link" href="#plugin"></a></h2>

<p>Slurm allows container developers to create <a href="plugins.html">SPANK
Plugins</a> that can be called at various points of job execution to support
containers. Any site using one of these plugins to start containers <b>should
not</b> have an "oci.conf" configuration file. The "oci.conf" file activates the
builtin container functionality which may conflict with the SPANK based plugin
functionality.</p>

<p>The following projects are third party container solutions that have been
designed to work with Slurm, but they have not been tested or validated by
SchedMD.</p>

<h3 id="shifter">Shifter<a class="slurm_link" href="#shifter"></a></h3>

<p><a href="https://github.com/NERSC/shifter">Shifter</a> is a container
project out of <a href="http://www.nersc.gov/">NERSC</a>
to provide HPC containers with full scheduler integration.

<ul>
	<li>Shifter provides full
		<a href="https://github.com/NERSC/shifter/wiki/SLURM-Integration">
			instructions to integrate with Slurm</a>.
	</li>
	<li>Presentations about Shifter and Slurm:
		<ul>
			<li> <a href="https://slurm.schedmd.com/SLUG15/shifter.pdf">
				Never Port Your Code Again - Docker functionality with Shifter using SLURM
			</a> </li>
			<li> <a href="https://www.slideshare.net/insideHPC/shifter-containers-in-hpc-environments">
				Shifter: Containers in HPC Environments
			</a> </li>
		</ul>
	</li>
</ul>
</p>

<h3 id="enroot1">ENROOT and Pyxis<a class="slurm_link" href="#enroot1"></a></h3>

<p><a href="https://github.com/NVIDIA/enroot">Enroot</a> is a user namespace
container system sponsored by <a href="https://www.nvidia.com">NVIDIA</a>
that supports:
<ul>
	<li>Slurm integration via
		<a href="https://github.com/NVIDIA/pyxis">pyxis</a>
	</li>
	<li>Native support for Nvidia GPUs</li>
	<li>Faster Docker image imports</li>
</ul>
</p>

<h3 id="sarus">Sarus<a class="slurm_link" href="#sarus"></a></h3>

<p><a href="https://github.com/eth-cscs/sarus">Sarus</a> is a privileged
container system sponsored by ETH Zurich
<a href="https://user.cscs.ch/tools/containers/sarus/">CSCS</a> that supports:
<ul>
	<li>
		<a href="https://sarus.readthedocs.io/en/latest/config/slurm-global-sync-hook.html">
			Slurm image synchronization via OCI hook</a>
	</li>
	<li>Native OCI Image support</li>
	<li>NVIDIA GPU Support</li>
	<li>Similar design to <a href="#shifter">Shifter</a></li>
</ul>
Overview slides of Sarus are
<a href="http://hpcadvisorycouncil.com/events/2019/swiss-workshop/pdf/030419/K_Mariotti_CSCS_SARUS_OCI_ContainerRuntime_04032019.pdf">
	here</a>.
</p>

<hr size=4 width="100%">

<p style="text-align:center;">Last modified 26 June 2025</p>

<!--#include virtual="footer.txt"-->