CI/CD Pipelines on GCP

Continuous Integration and Continuous Delivery (CI/CD) is the practice of automatically building, testing, and deploying software whenever changes are made. Google Cloud provides a comprehensive set of services for building CI/CD pipelines — Cloud Build for execution, Artifact Registry for artefact storage, Cloud Deploy for managed delivery, and various deployment targets including Cloud Run, GKE, and App Engine.

---

CI/CD Fundamentals

Continuous Integration (CI)

CI is the practice of frequently merging code changes into a shared repository and automatically building and testing each change:

Step	Purpose	Tool
Code commit	Developer pushes code	Git (CSR, GitHub, GitLab)
Build trigger	Detect the change	Cloud Build triggers
Compile/Build	Compile code, build artefacts	Cloud Build
Unit tests	Run automated tests	Cloud Build
Lint/Static analysis	Check code quality	Cloud Build
Container build	Build Docker images	Cloud Build
Push artefact	Store built artefacts	Artifact Registry
Scan	Vulnerability scanning	Container Analysis

Continuous Delivery (CD)

CD extends CI by automatically deploying verified artefacts to target environments:

Step	Purpose	Tool
Deploy to staging	Automated deployment after CI	Cloud Build / Cloud Deploy
Integration tests	Test in staging environment	Cloud Build
Approval gate	Manual approval for production	Cloud Deploy
Deploy to production	Controlled production release	Cloud Deploy
Canary/Blue-green	Gradual rollout strategy	Cloud Deploy
Monitor	Post-deployment verification	Cloud Monitoring

---

End-to-End Pipeline Architecture

A typical GCP CI/CD pipeline looks like this:

Push to GitHub
    |
    v
Cloud Build Trigger
    |
    v
Cloud Build (CI)
  - Install dependencies
  - Run lint
  - Run tests
  - Build Docker image
  - Push to Artifact Registry
  - Scan for vulnerabilities
    |
    v
Cloud Deploy (CD)
  - Deploy to dev
  - Deploy to staging (auto)
  - Deploy to production (manual approval)
    |
    v
Cloud Run / GKE / App Engine

---

Building a CI Pipeline

Complete CI Configuration

# cloudbuild.yaml
steps:
  # Install dependencies
  - name: 'node:18'
    id: 'install'
    entrypoint: 'npm'
    args: ['ci']

  # Run linter
  - name: 'node:18'
    id: 'lint'
    entrypoint: 'npm'
    args: ['run', 'lint']
    waitFor: ['install']

  # Run unit tests
  - name: 'node:18'
    id: 'test'
    entrypoint: 'npm'
    args: ['test']
    waitFor: ['install']
    env:
      - 'CI=true'

  # Build Docker image
  - name: 'gcr.io/cloud-builders/docker'
    id: 'build-image'
    args:
      - 'build'
      - '-t'
      - 'europe-west1-docker.pkg.dev/$PROJECT_ID/my-repo/my-app:$SHORT_SHA'
      - '-t'
      - 'europe-west1-docker.pkg.dev/$PROJECT_ID/my-repo/my-app:latest'
      - '.'
    waitFor: ['lint', 'test']