apptainer-capability

Manage Linux capabilities for Apptainer container users and groups

TLDR

List capabilities granted to a specific user

$ sudo apptainer capability list --user [username]

Grant a capability to a user

$ sudo apptainer capability add --user [username] [CAP_NET_RAW]

Drop a capability from a user

$ sudo apptainer capability drop --user [username] [CAP_NET_RAW]

Grant all capabilities to a group

$ sudo apptainer capability add --group [groupname] all

List all available Linux capabilities with descriptions

$ apptainer capability avail

Drop all capabilities from a user

$ sudo apptainer capability drop --user [username] all

SYNOPSIS

apptainer capability subcommand [options]

apptainer capability manages Linux capabilities granted to users and groups for use inside Apptainer containers. Administrators use this command to authorize specific users or groups to request particular capabilities at container runtime.Capabilities are stored in a capability.json file maintained by Apptainer. Granting a capability does not automatically enable it inside containers — users must explicitly request granted capabilities at runtime using the --add-caps flag with commands like apptainer exec or apptainer run.

PARAMETERS

--user name

Target a specific user for add, drop, or list operations.

--group name

Target a specific group for add, drop, or list operations.

SUBCOMMANDS

add

Grant one or more Linux capabilities to a user or group. Requires root.

drop

Revoke one or more Linux capabilities from a user or group. Requires root.

list

Display capabilities currently assigned to a user or group.

avail

Show all recognized Linux capabilities with brief descriptions.

CAVEATS

Granting Linux capabilities to users is usually equivalent to granting root-level access on the host system. Most capabilities allow users to break out of containers and escalate privileges. This feature is intended for trusted environments, not multi-tenant HPC clusters. Both add and drop accept the case-insensitive keyword all to operate on every available capability at once.