circletron

Circletron is a tool to simplify working with monorepos. Currently monorepos managed via lerna are supported.

It allows splitting up .circle/config.yml among subprojects in the monorepo such that each subproject can define its own commands, workflows and jobs. These jobs can then be automatically skipped when not required.

How to use

1. Create a minimal .config/circle.yml like this:

version: 2.1
setup: true
orbs:
  circletron: circletron/[email protected]

workflows:
  trigger-jobs:
    jobs:
      - circletron/trigger-jobs

2. You may create a circle.yml in the root of your monorepo. The jobs in this circle.yml will always run and any commands, executors and orbs defined in this circle.yml will be available in the circle.yml of all other subpackages.

3. Create a circle.yml in each subpackage within the monorepo which requires automatiion. The jobs in this circle configuration are run only when there are changes in the respective branch to a file within this subpackage or changes to a file in one of its dependents. conditional: false may be added to a job to specify that it must always run even when no changes to the subpackage or one of its dependencies is detected.

4. Optionally create a .circle/lerna.yml file to specify dependencies within projects, e.g.

dependencies:
  project1:
    - project2
    - project3

will cause jobs within project1 to run when changes are detected in either project1, project2 or project3.

Details

It is useful to set up branch protection rules to prevent code from being merged when a CI job does not pass. When jobs are omitted then the PR will never be mergeable since the job will remain in a pending state. For this reason circletron will never omit a job that was determined not to be run, instead the job will be replaced wit a simple job that echos "Job is not required" and return a success exit status.

For the following branches all jobs will run:

• main
• master
• develop
• branches starting with release/

This will be configurable in a future release.