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Continuous Integration / Continuous Delivery

Continuous Integration and Delivery means continuously building, testing, and delivering your code, you can reap huge stability, speed, and flexibility benefits.

Benefits of CI/CD:

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  • CI/CD systems can differ a lot depending on the technology
  • However, there are 5 key benefits one can see from CI/CD:
    • Empowering teams: The pipeline is a self service system. This makes the system transparent and easy to use by anyone
    • Cycle Time: The cycle time from code commit to production is reduced significantly
    • Security issues: Reduces security issues as security compliance integrates each time
    • Continuous practice: Release date is not a big event
    • More value: Spend less time doing unplanned work and more time value added work
  • A typical CI/CD pipeline in practice: 
        graph LR
    A[Source Code] --> B[Version Control];
    B -->C[Build Tool];
    C --> D[Build & tests];
    D --> G[Artifact store];
    G --> H[Local Deployment]
    H --> I[Deployed and tested]
    I --> J{Testing successful?}
    J --> |YES| K[Production Deployment]
    J --> |NO| L[Go to start of cycle]

Sample CI/CD pipeline

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  • Version Control
    • Standard tool: Git
    • Version Control best practices:
      • Always use version control
      • Put everything in version control
      • Commit often. small batches
      • Succint Commit messages
      • do not commit code whose build is failing
      • Consider using master branch approach (TBD)
      • precommit hooks for quality control
  • Continuous Integration
    • Defacto app: Jenkins
    • Best practices:
      • Start with a clean build
      • Build to pass the coffee test
      • Run tests locally before committing
      • Do not commit to a build which is broken
      • Do not leave the build broken
      • Do not remove failing tests. remove them if they are not valid
      • Use notifications to communicate build status
      • Datadog can be used to co-relate errors to code changes
  • Artifact Repositories
    • Examples: Nexus or Artifactory
    • Benefits of packaging code as artifacts:
      • Composeability
      • Reliability
      • Security
      • Shareability
  • Testing & Continuous Delivery:
    • Unit Testing: Run with builds. Eg. JUnit
    • Integration Testing: Run to check integration of various components. Eg. ServerSpec
    • E2E testing: Run to check from a user flow perspective. Eg. Selenium tests
    • Test philosophy:
      • TDD
      • BDD : Cucumber
      • ATDD : Acceptance Test driven development
    • Application Deployment and release:
      • Deploy with same artifact, in the same way, in an identical environment
      • Tool: Ansible