A snap component is part of a snap that has been declared as optional. A snap component may then be either installed or not installed alongside its host snap. See Components for further details.
Component support requires snapd 2.67+.
Installing components
Components can be installed with the snap install command:
snap install my-snap+comp1+comp2
The syntax
<snap_name>+<comp_1>+...+<comp_N>will be used to refer to components from the command line.
The above command will install my-snap alongside components comp1 and comp2. If the snap is already installed, the command will instead install only the missing components.
It is also possible to install components from local files. If unasserted, they can be installed only if the host snap is unasserted too and you will need to use the --dangerous flag:
snap install --dangerous ./my-snap+comp1+comp2_1.0.comp
Once installed, the (asserted) components will refresh when new revisions are available in the store, in the same way as for snaps.
When refreshing a snap, all components will refresh to the new revisions tuple. If the new snap revision does not define some components defined in the previously installed snap and that are currently installed, those components will be removed.
Updating components
It is also possible to refresh a snap and install a component at the same time:
snap refresh my-snap+comp1
Listing components
The snap components command is used to list the components installed and available on the system:
$ snap components
Component Status Type
snap-with-comps+one installed standard
snap-with-comps+two installed standard
snap-with-comps+three available standard
other-snap-with-comps+one installed standard
other-snap-with-comps+two installed standard
other-snap-with-comps+three available standard
A snap name can be optionally provided to filters the list of reported components to those only associated with the provided snap:
$ snap components snap-with-comps
Component Status Type
snap-with-comps+one installed standard
snap-with-comps+two installed standard
snap-with-comps+three available standard
Note that there are some plans for a "snap component" subcommand, but that is not yet implemented and there are talks of changing its design.
Removing components
To remove only the components, use the “remove” command, followed by the snap and component names:
snap remove my-snap+comp1+comp2
To remove the snap plus any installed components, just remove the snap:
snap remove my-snap