What is Continuous Integration and Continuous Delivery/Deployment?

Continuous Integration

• Developers regularly merge code changes into a central repository
  • this triggers automated builds and tests
• CI is a build or integration phase
  • requires both an automation component, that is a CI or build service
  • AND a cultural component, this means developers learn to integrate frequently
• Key Goals
  • find and address bugs more quickly
  • improve software quality
  • reduce the time needed to validate and release new updates
• Focus on smaller commits and smaller code changes
  • commit code frequently, at least once a day
  • pull from repository before pushing, ensure local host is merged
  • after push build server runs various tests and rejects/accepts the commit
• Challenges
  • more frequent commits to codebase
  • single source code repository
  • automating builds
  • automating testing
• Additional Challenges
  • test in prod-like environments
  • make process visible to team
  • allow developers to obtain any version of the application

Continuous Delivery and Deployment

• Code changes are automatically built, tested and prepared for production release
• Expands on continuous integration
  • deploys all code changes to a testing environment, a production environment or both
    • after a build stage has been completed
  • Continuous delivery can be fully automated with a workflow process
  • OR partially automated with manual steps
  • ideally, developers should always have a deployment-ready build artifact
    • deployment ready means build has passed through a standardized testing process
  • With CD, revisions are deployed to production automatically without explicit approval
    • entire software release process should be automated
    • allows for continuous customer feedback loop early in product lifecycle