Ubuntu image builder

This tool is used to build Ubuntu images:

• Ubuntu Core snap-based images from model assertions
• Ubuntu classic preinstalled images using image definition

Future versions should be generalized to build more (eventually all) Ubuntu images.

Requirements

Ubuntu 18.04 (Bionic Beaver) is the minimum platform requirement, but Ubuntu 20.04 (Focal Fossa) or newer is recommended. All required third party packages are available in the Ubuntu archive.

To run the test suite locally, install all the build dependencies named in the debian/control file. Run the following command from the root directory of the repository:

$ sudo apt build-dep ./

Alternatively, install the packages named in the Build-Depends field.

Project details

• Project home: https://github.com/Canonical/ubuntu-image
• Report bugs at: https://bugs.launchpad.net/ubuntu-image
• Git clone: https://github.com/Canonical/ubuntu-image.git
• Reference page: ubuntu-image syntax and options
• gadget.yaml specification: Gadget snaps

Build instructions

1. Ensure golang >= 1.21 is installed.
2. Clone the Git repository using git clone https://github.com/canonical/ubuntu-image.git.
3. cd into the newly cloned repository.
4. Run go build -o . ./....
5. The newly compiled executable ubuntu-image is created in the current directory.

Release process

ubuntu-image is released as a snap on the Snap Store.

When changes are merged in the main branch, a new snap is automatically built and pushed to the latest/edge channel.

When we think we have a "stable enough" version that we don't want to break with future merges in main, we promote it to latest/candidate. To do so:

1. Create a new branch.
2. Update the version in snapcraft.yaml.
3. Add a changelog entry to debian/changelog.
4. Commit, create a version tag, and push.
5. Merge.
6. Wait for the build to appear in latest/edge.
7. Promote the build to latest/candidate.

After a couple of weeks, if our "early adopters" are happy and we did not break any build or if we did not spot any major fix to do, promote this version from latest/candidate to latest/stable.

This way, our users can choose between:

• The latest/edge channel updated as soon as we merge changes.
• The latest/candidate channel with new features/bugfixes but with potentially some newly introduced bug. This channel would be good to let users test requested features.
• The latest/stable channel that should hopefully contain a rather "bug-free" version because it was tested in more various situations.