Going monorepo

All your repos are belong to us

Before git

• Creating a new repository was a pain

  • git init

• Setting up continuous integration was a pain
  • .travis-ci.yml
  • .gitlab-ci.yml
  • Jenkinsfile

Here come the repositories

• Arranged around technological stacks
  • around people and skills
• Simple commit history per-repository
• Fast Continuous Integration
• Simpler file structure per-repository
• Clean separation of concerns

Code reviews

• Reviews are feature based
• As many reviews as there are impacted repositories

What happens when everything is in a single repository ?

Monorepo

• Single commit history
• Code reviews span across services
• No need to synchronize merges
• One commit / feature becomes available
• Possible to have integration tests on multiple services as part of CI

Be careful

• Mono-repo does not mean monolith
• Keep services separate
• Think of it as a modular monolith
• Each service should be independant :
  • compile
  • test (alone)
  • deploy

Disadvantages

• Continuous Integration can be a burden
• Even if services are built in parallel
• Needs work to build only the services which have changed

Who should use monorepos ?

1. Single team projects
2. Projects with a lot of dependencies
   • to avoid dealing with integrations and compatibilities
3. Big companies like Google who are mature enough

Who should not use monorepos ?

• Projects which have absolutely no link between one another

Questions ?