h2(#overview). Overview
-Arvados can be configured to use "Singularity":https://sylabs.io/singularity/ instead of Docker to execute containers on cloud nodes or a SLURM/LSF cluster. Singularity may be preferable due to its simpler installation and lack of long-running daemon process and special system users/groups.
-
-*Current limitations*:
-* Even when using the singularity runtime, users' container images are expected to be saved in Docker format using @arv keep docker@. Arvados converts the Docker image to Singularity format (@.sif@) at runtime as needed. Specifying a @.sif@ file as an image when submitting a container request is not yet supported.
-* Singularity does not limit the amount of memory available in a container. Each container will have access to all memory on the host where it runs, unless memory use is restricted by SLURM/LSF.
-* Programs running in containers may behave differently due to differences between Singularity and Docker.
-** The root (image) filesystem is read-only in a Singularity container. Programs that attempt to write outside a designated output or temporary directory are likely to fail.
-** The Docker ENTRYPOINT instruction is ignored.
-* Arvados is tested with Singularity version 3.7.4. Other versions may not work.
+Please refer to the "Singularity":{{site.baseurl}}/architecture/singularity.html documentation in the Architecture section.
h2(#configuration). Configuration
-To use singularity, first make sure "Singularity is installed":https://sylabs.io/guides/3.7/user-guide/quick_start.html on your cloud worker image or SLURM/LSF compute nodes as applicable. Note @squashfs-tools@ is required.
+To use singularity, first make sure "Singularity is installed":https://sylabs.io/guides/3.7/user-guide/quick_start.html on your cloud worker image or Slurm/LSF compute nodes as applicable. Note @squashfs-tools@ is required.
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<pre><code>$ <span class="userinput">singularity version</span>
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Restart your dispatcher (@crunch-dispatch-slurm@, @arvados-dispatch-cloud@, or @arvados-dispatch-lsf@) after updating your configuration file.
+
+h2(#singularity_configuration). Singularity configuration
+
+Docker images are converted on the fly by @mksquashfs@, which can consume a considerable amount of RAM. The RAM usage of mksquashfs can be restricted in @/etc/singularity/singularity.conf@ with a line like @mksquashfs mem = 512M@. The amount of memory made available for mksquashfs should be configured lower than the smallest amount of memory requested by a container on the cluster to avoid the conversion being killed for using too much memory.
projects / arvados.git / blobdiff