Advanced Tagging

Some users incorporate non-trivial workflows that can require advanced tagging techniques. These workflows can be handled in the Factory Definition

Terminology

Platform Build - A build created by a change to the LmP (lmp-manifest.git or meta-subscriber-overrides.git). This is the base OS image.

Container Build - A build created by a change to containers.git.

Target - This an entry in a factory’s TUF targets.json file. It represents what should be thought of as an immutable combination of the Platform build’s OSTree hash + the output of a Container build.

Tag - A Target has a “custom” section where with a list of Tags. The tags can be used to say things like “this is a development build” or this is a “production” build.

Scenario 1: A new platform build that re-uses containers

A Factory is set up with the normal master branch:

lmp:
  tagging:
    refs/heads/master:
      - tag: master
containers:
  tagging:
    refs/heads/master:
      - tag: master

You’d like to introduce a new stable branch from the LmP but have it use the latest containers from master. This can be done with:

lmp:
  tagging:
    refs/heads/master:
      - tag: master
    refs/heads/stable:
      - tag: stable
        inherit: master
containers:
  tagging:
    refs/heads/master:
      - tag: master
      - tag: stable

Consider this pseudo targets example:

targets:
  build-1:
    ostree-hash: DEADBEEF
    docker-apps: foo:v1, bar:v1
    tags: stable
  build-2:
    ostree-hash: GOODBEEF
    docker-apps: foo:v2, bar:v2
    tags: master

If a change to the stable branch was pushed to the LmP, a new target, build-3, would be added. The build logic would then look through the targets list to find the most recent master target so that it can copy those docker-apps. This would result in a new target:

build-3:
  ostree-hash: NEWHASH
  docker-apps: foo:v2, bar:v2
  tags: stable

On the other hand, there might also be a new container build for master. In this case the build logic will produce two new targets:

build-4:  # for stable it will be based on build-3
  ostree-hash: NEWHASH
  docker-apps: foo:v3, bar:v3
  tags: stable

build-4:  # for master, it will be based on build-2
  ostree-hash: GOODBEEF
  docker-apps: foo:v3, bar:v3
  tags: master

Scenario 2: Multiple container builds using the same platform

This scenario is the reverse of the previous one. A factory might have a platform build tagged with master. However, there are two versions of containers being worked on: master and foo. This could be handled with:

lmp:
  tagging:
    refs/heads/master:
      - tag: master
      - tag: foo
containers:
  tagging:
    refs/heads/master:
      - tag: master
    refs/heads/foo:
      - tag: foo
        inherit: master

Scenario 3: Multiple teams, different cadences

Some organizations may have separate core platform and application teams. In this scenario, it may be desirable to let each team move at their own decoupled paces. Furthermore, the application team might have stages(branches) of development they are working on. This could be handled with something like:

lmp:
  tagging:
    refs/heads/master:
      - tag: master
containers:
  tagging:
    refs/heads/master:
      - tag: master
    refs/heads/dev:
      - tag: dev
        inherit: master
    refs/heads/qa:
      - tag: qa
        inherit: master

This scenario is going to produce master tagged builds that have no containers, but can be generically verified. Then each containers.git branch will build Targets and grab the latest master tag to base its platform on. NOTE: Changes to master don’t cause new container builds. In order to get a container’s branch updated to the latest master a user would need to push an empty commit to containers.git to trigger a new build:

# from branch qa
git commit --allow-empty -m 'Pull in latest platform changes from master'