A branch is an optional finer subdivision of a channel which allows for the creation of a temporary and short-lived sequence of snaps. They’re typically used by snap developers to push fixes or temporary experimental builds on-demand.
Branch names convey their purpose, such as fix-for-bug123, but the name isn’t exposed in the normal way, such as with snap info. Instead, they can only be installed by someone who knows the branch name, and this is usually only shared by the snap developer to test a specific fix or release.
After 30 days with no further updates, a branch will be closed automatically. The replacement snap will then be chosen from the next most conservative risk-level of the same track. For example, beta/fix-for-bug123 will fall back to beta after the fix-for-bug123 branch is closed.
- Creating a branch
- Installing a snap from a branch
- Promoting a snap from a branch
- Setting a default branch
Creating a branch
To publish a built and tested snap to a new branch, the snap developer can use the same snapcraft upload process used to publish the snap, but with a full channel description that includes track, risk-level and a new arbitrary branch name:
snapcraft upload <snap-name.snap> --release=<track>/<risk>/<branch>
The branch name cannot contain “_” or “/” character.
See Releasing your app for more general details on publishing a snap.
Many snaps will have only a latest track, while others may use different tracks for each supported release, such as Node.js or separate tracks for stable and insider builds, such as Skype. These details can be retrieved with the snap info command:
$ snap info qvge
name: qvge
[...]
channels:
latest/stable: 0.6.0-1 2021-08-28 (45) 103MB -
latest/candidate: 0.6.1 2021-11-18 (81) 101MB -
latest/beta: 0.6.1 2021-11-18 (81) 101MB -
latest/edge: 0.6.3 2022-02-28 (225) 101MB -
The above example shows a snap with only a latest track. To publish a locally built snap to its latest/beta channel with a new branch called fix-test-062, you would run the following command:
$ snapcraft upload qvge_0.6.2_amd64.snap --release=latest/beta/fix-test-062
Preparing to upload 'qvge_0.6.2_amd64.snap'.
After uploading, the resulting snap revision will be released to 'latest/beta/fix-test-062' when it passes the Snap Store review.
Running the review tools before pushing this snap to the Snap Store.
Generating delta for 'qvge_0.6.2_amd64.snap'.
Pushing 'qvge_0.6.2_amd64.snap.xdelta3' [=================================================================================] 100%
Processing...|
released
Revision 230 of 'qvge' created.
Track Arch Channel Version Revision Expires at
latest amd64 stable 0.6.0-1 45
candidate 0.6.1 81
beta 0.6.1 81
edge 0.6.3 225
beta/fix-test-062 0.6.2 230 2022-05-13T11:10:26Z
The above shows that the new branch now exists under the latest track, beta branch. It can be confirmed by the snap developer with the snapcraft status command, but the branch will not appear in the output to snap info:
$ snapcraft status qvge
Track Arch Channel Version Revision Expires at
latest amd64 stable 0.6.0-1 45
candidate 0.6.1 81
beta 0.6.1 81
edge 0.6.3 225
beta/fix-test-062 0.6.2 230 2022-05-13T11:10:26Z
$ snap info qvge
name: qvge
[...]
channels:
latest/stable: 0.6.0-1 2020-08-28 (45) 103MB -
latest/candidate: 0.6.1 2020-11-18 (81) 101MB -
latest/beta: 0.6.1 2020-11-18 (81) 101MB -
latest/edge: 0.6.3 2021-09-28 (225) 101MB -
Installing a snap from a branch
To install a snap from a branch, the user needs to know its name. This is typically shared by the developer, either through whatever issue tracking system might be used by the project, or shared informally via a forum post or message.
When you know the branch name, the snap can be installed with the snap install <snap-name> --channel command, followed by the full channel description. To install a snap called qvge from its beta/fix-test-062 branch, for instance, you’d type the following:
$ snap install qvge --channel beta/fix-test-062
qvge (beta/fix-test-062) 0.6.2 installed
If the snap is already installed, replace install with refresh.
After 30 days with no further updates, a branch will be closed automatically. The replacement snap will then be chosen from the next most conservative risk-level of the same track. For example, beta/fix-test-061 will fall back to whatever snap is provided by beta after the fix-test-061 branch is closed.
Promoting a snap from a branch
If a snap in a branch proves stable and fixes whatever issue necessitated the branch release, it can be promoted to another channel just like any other snap.
A branch is visible on a snap’s ‘Release’ page in the Snap Store web UI, from where it can be promoted to a different channel just like any other release:
A snap from a branch can also be promoted to another channel using snapcraft on the command line:
$ snapcraft release qvge 230 beta
Track Arch Channel Version Revision Expires at
latest amd64 stable 0.6.0-1 45
candidate 0.6.1 81
beta 0.6.2 230
edge 0.6.2 231
beta/fix-test-062 0.6.2 230 2022-05-13T11:10:26Z
After a snap has been promoted, the branch will remain in-place until its expiry.
For more details on promoting snaps to different channels, see Release management.
Setting a default track
All snaps have a default track. When not specified explicitly, a snap is installed from the default track and without the snap publisher specifying otherwise, the default track is called latest
A default track can be specified manually with snapcraft when a snap has more than one track:
snapcraft set-default-track <snap-name> <default-track-name>
When no track is specified at install time, an implicit track install will install from <default-track-name> instead of latest:
snap install <snap-name>
Note that the default track does NOT remove latest; latest is never a pointer to another track and remains available:
snap install <snap-name> --channel=latest