====== Apptainer ======

   * Category: Vendor provision
   * Access method: Loaded from Linux module software
   * License: Open Source 
   * Command Line: **Yes**
   * Desktop GUI: **Yes** (no specific support for GUI, but can be used at the desktop without issue)

Apptainer is a software container tool. It allows you to encapsulate an application and all the necessary supporting tools and libraries, enabling you to run the application without needing to locally install all of the supporting tools. You can move the container from machine to machine - for example from your desktop to a server, or HPC - without needing to make any changes to the application, or needing administrative permissions.

On an HPC, this is an ideal way of having a repeatable environment to run code between vastly different systems and ensure reproducibility.

   * For more information, see https://apptainer.org/

Apptainer **replaces** the use of Singularity, which should now be considered deprecated.

===== Running =====

=== Versions ===

<code lang=shell-session>
$ module avail apptainer
</code>

=== Loading ===

<code lang=shell-session>
$ module load apptainer
</code>

=== Testing ===

<code lang=shell-session>
$ module load apptainer
$ module list

Currently Loaded Modules:
  1) squashfuse/0.6.1   2) apptainer/1.4.1

$ apptainer
Usage:
  apptainer [global options...] <command>

Available Commands:
  build       Build an Apptainer image
  cache       Manage the local cache
  capability  Manage Linux capabilities for users and groups
  checkpoint  Manage container checkpoint state (experimental)
  completion  Generate the autocompletion script for the specified shell
  config      Manage various apptainer configuration (root user only)
  delete      Deletes requested image from the library
  exec        Run a command within a container
  inspect     Show metadata for an image
  instance    Manage containers running as services
  key         Manage OpenPGP keys
  keyserver   Manage apptainer keyservers
  oci         Manage OCI containers
  overlay     Manage an EXT3 writable overlay image
  plugin      Manage Apptainer plugins
  pull        Pull an image from a URI
  push        Upload image to the provided URI
  registry    Manage authentication to OCI/Docker registries
  remote      Manage apptainer remote endpoints
  run         Run the user-defined default command within a container
  run-help    Show the user-defined help for an image
  search      Search a Container Library for images
  shell       Run a shell within a container
  sif         Manipulate Singularity Image Format (SIF) images
  sign        Add digital signature(s) to an image
  test        Run the user-defined tests within a container
  verify      Verify digital signature(s) within an image
  version     Show the version for Apptainer

Run 'apptainer --help' for more detailed usage information.
</code>

=== Application Help Pages ===

   * [[advanced:apptainer|Apptainer help guide]] - Our local support page for Apptainer on Comet

===== Requests =====

Requests for new/alternate versions of this package should be submitted via the [[https://nuservice.ncl.ac.uk|NUIT ITService]] website using the **HPC Software - Installation** category.

Software requests will be collated, prioritized and submitted to our HPC support vendor. 

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