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<h1>job_container/tmpfs</h1>

<h2 id="overview">Overview<a class="slurm_link" href="#overview"></a></h2>
<p>job_container/tmpfs is an optional plugin that provides job-specific, private
temporary file system space.</p>

<p>When enabled on the cluster, a filesystem namespace will be created for each
job with a unique, private instance of /tmp and /dev/shm for the job to use.
These directories can be changed with the <b>Dirs=</b> option in
job_container.conf. The contents of these directories will be removed at job
termination.</p>

<h2 id="installation">Installation
<a class="slurm_link" href="#installation"></a>
</h2>
<p>This plugin is built and installed as part of the default build, no extra
installation steps are required.</p>

<h2 id="setup">Setup<a class="slurm_link" href="#setup"></a></h2>
<p>Slurm must be configured to load the job container plugin by adding
<b>JobContainerType=job_container/tmpfs</b> and <b>PrologFlags=contain</b> in
slurm.conf. Additional configuration must be done in the job_container.conf
file, which should be placed in the same directory as slurm.conf.</p>

<p>Job containers can be configured for all nodes, or for a subset of nodes.
As an example, if all nodes will be configured the same way, you would put the
following in your job_container.conf:</p>

<pre>
AutoBasePath=true
BasePath=/var/nvme/storage
</pre>

<p>A full description of the parameters available in the job_container.conf
file can be found <a href="job_container.conf.html">here</a>.</p>

<h2 id="initial_testing">Initial Testing
<a class="slurm_link" href="#initial_testing"></a>
</h2>
<p>An easy way to verify that the container is working is to run a job and
ensure that the /tmp directory is empty (since it normally has some other
files) and that "." is owned by the user that submitted the job.</p>
<pre>
tim@slurm-ctld:~$ srun ls -al /tmp
total 8
drwx------  2 tim    root 4096 Feb 10 17:14 .
drwxr-xr-x 21 root   root 4096 Nov 15 08:46 ..
</pre>

<p>While a job is running, root should be able to confirm that
<code>/$BasePath/$JobID/_tmp</code> exists and is empty. This directory is bind
mounted into the job. <code>/$BasePath/$JobID</code> should be owned by root,
and is not intended to be accessible to the user.</p>

<h2 id="spank">SPANK<a class="slurm_link" href="#spank"></a></h2>
<p>This plugin interfaces with the SPANK api, and automatically joins the job's
container in the following functions:</p>
<ul>
<li>spank_task_init_privileged()</li>
<li>spank_task_init()</li>
</ul>

<p>In addition to the job itself, the TaskProlog will also be executed inside
the container.</p>

<p style="text-align:center;">Last modified 29 November 2023</p>

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