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Table of Contents Continuous Integration (CI) Continuous Deployment (CD) Virtualization Walking skeleton Continuous Delivery (??)

CI requires:

• developer
  • write unit test code
  • write code, and run it against test code
  • send code and test code to SCM on a feature branch
• integration server, on feature branch
  • perform quality check (code quality, test coverage)
  • build a new version
  • run unit/integration test code against it
• developer
  • submit pull request
• integration server
  • try to merge feature branch into temporary branch
  • build a new version
  • run unit/integration test code against it
  • prepare code review
• team
  • run code review
  • approve pull request
• integration server
  • merge feature branch into master
  • run unit/integration test code against it
  • build a new version
  • publish a new version in a repository

CD requires of :

• deployment server to
  • watch for new version in a repository
  • deploy it a test environment, enabling manual tests
  • when tests passed, deploy it to a production environment

CI and CD are easiest with virtualization, as it guarantee an identical execution context in all environments, reducing impedance mismatch. Operating-system-level virtualization offer better performance than complete VM, and image are smaller, causing it to be called "lightweight" virtualization.

CI/CD came from XP, where it was used to deliver into production as fast as possible. Freeman and Pryce in GOOSE recommend starting any project with a walking skeleton, eg. building the simplest possible app (king of hello-world) and sending it into production using CI/CD.

When there's no automated tests, there's no CI/CD. One solution remais: automate build and deploy. There's no continuity any more. Manually trigger the build and deploy to an environment.