An Apptainer plugin is a package that can be dynamically loaded by the Apptainer runtime, augmenting Apptainer with experimental, non-standard and/or vendor-specific functionality. Currently, plugins are able to add commands and flags to Apptainer. In the future, plugins will also be able to interface with more complex subsystems of the Apptainer runtime.
list command prints the currently installed plugins.
$ apptainer plugin list There are no plugins installed.
Plugins are packaged and distributed as binaries encoded with the
versatile Singularity Image Format (SIF). However, plugin authors may
also distribute the source code of their plugins. A plugin can be
compiled from its source code with the
compile command. A sample
test-plugin is included with the Apptainer source code.
$ apptainer plugin compile examples/plugins/test-plugin/
Upon successful compilation, a SIF file will appear in the directory of the plugin’s source code.
$ ls examples/plugins/test-plugin/ | grep sif test-plugin.sif
Currently, all plugins must be compiled from the Apptainer source code tree.
Also, the plugins mechanism for the Go language that Apptainer is
written in is quite restrictive - it requires extremely close version
matching of packages used in a plugin to the ones used in the program
the plugin is built for. Additionally Apptainer is using build
time config to get the source tree location for
compile so that you don’t need to export environment variables etc,
and there isn’t mismatch between package path information that Go
uses. This means that at present you must:
Build plugins using the exact same version of the source code, in the same location, as was used to build the Apptainer executable.
Use the exact same version of Go that was used to build the executable when compiling a plugin for it.
Every plugin encapsulates various information such as the plugin’s
author, the plugin’s version, etc. To view this information about a
plugin, use the
$ apptainer plugin inspect examples/plugins/test-plugin/test-plugin.sif Name: sylabs.io/test-plugin Description: This is a short test plugin for Apptainer Author: Michael Bauer Version: 0.0.1
To install a plugin, use the
install command. This operation
requires root privilege.
$ sudo apptainer plugin install examples/plugins/test-plugin/test-plugin.sif $ apptainer plugin list ENABLED NAME yes sylabs.io/test-plugin
After successful installation, the plugin will automatically be enabled.
Any plugin can be disabled with the
disable command and re-enabled
enable command. Both of these operations require root
$ sudo apptainer plugin disable sylabs.io/test-plugin $ apptainer plugin list ENABLED NAME no sylabs.io/test-plugin $ sudo apptainer plugin enable sylabs.io/test-plugin $ apptainer plugin list ENABLED NAME yes sylabs.io/test-plugin
Finally, to uninstall a plugin, use the
uninstall command. This
operation requires root privilege.
$ sudo apptainer plugin uninstall sylabs.io/test-plugin Uninstalled plugin "sylabs.io/test-plugin". $ apptainer plugin list There are no plugins installed.
Writing a Plugin
Developers interested in writing Apptainer plugins can get started by reading the Go documentation for the plugin package. Furthermore, reading through the source code for the example plugins will prove valuable. More detailed plugin development documentation is in the works and will be released at a future date.