Eventually Bitwise

CI/CD Pipelines

Overview

CI/CD stands for Continuous Integration and Continuous Deployment (or Delivery). It is a set of practices and tools that automate the process of integrating code changes from multiple contributors into a shared repository and deploying them to production.

Core Concepts

  • Continuous Integration (CI):
    • Automated Build: Every commit triggers a build process.
    • Automated Testing: Running the unit, integration, and E2E tests on every commit.
    • Goal: Detect integration errors as early as possible.
  • Continuous Delivery (CD):
    • Automated Release: The code is always in a deployable state, but the final push to production may be manual.
  • Continuous Deployment (CD):
    • Automated Production Push: Every change that passes the CI pipeline is automatically deployed to production without human intervention.
  • Deployment Strategies:
    • Blue-Green Deployment: Running two identical production environments. You switch traffic to the new version (Green) only after it’s verified.
    • Canary Deployment: Rolling out the change to a small subset of users first to monitor for errors.
    • Rolling Update: Gradually replacing old versions of the service with new ones.

Code Examples

# Conceptual GitHub Actions workflow
name: CI Pipeline
on: [push]
jobs:
  build-and-test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - run: npm install
      - run: npm test
      - run: npm run lint

Use Cases

  • Faster Time-to-Market: Reducing the time between a feature being conceptualized and being available to users.
  • Improved Stability: Automation eliminates human error during deployment.
  • Small, Frequent Releases: Instead of one giant “release day” every 6 months, you deploy small changes daily.

Gotchas

  • Pipeline Flakiness: When a test fails intermittently (flaky tests), developers stop trusting the CI pipeline.
  • Complexity: Managing complex deployment pipelines for microservices can be a significant operational burden.
  • Dependency Hell: Ensuring that the CI environment perfectly matches the production environment.

Related Notes

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