CI/CD Patterns
A comprehensive skill for designing and implementing continuous integration and deployment pipelines. Covers pipeline architecture, deployment strategies, quality gates, and platform-specific patterns for GitHub Actions and GitLab CI.
When to Use
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Designing new CI/CD pipelines from scratch
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Implementing deployment strategies (blue-green, canary, rolling)
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Setting up quality gates and approval workflows
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Configuring GitHub Actions or GitLab CI pipelines
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Implementing automated rollback mechanisms
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Creating multi-environment deployment workflows
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Integrating security scanning into pipelines
Pipeline Architecture
Pipeline Stages
A well-designed pipeline follows these stages in order:
Build -> Test -> Analyze -> Package -> Deploy -> Verify
Stage Breakdown:
Stage Purpose Failure Action
Build Compile code, resolve dependencies Fail fast, notify developer
Test Unit tests, integration tests Block deployment
Analyze SAST, linting, code coverage Block or warn based on threshold
Package Create artifacts, container images Fail fast
Deploy Push to environment Rollback on failure
Verify Smoke tests, health checks Trigger rollback
Pipeline Design Principles
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Fail Fast: Run quick checks (lint, unit tests) before slow ones
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Parallel Execution: Run independent jobs concurrently
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Artifact Caching: Cache dependencies between runs
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Immutable Artifacts: Build once, deploy everywhere
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Environment Parity: Dev, staging, and prod should be identical
Deployment Strategies
Blue-Green Deployment
Two identical production environments where traffic switches instantly.
Load Balancer
|
+------------+------------+
| |
[Blue v1.0] [Green v1.1]
(active) (standby)
When to Use:
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Zero-downtime requirements
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Need instant rollback capability
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Sufficient infrastructure budget for duplicate environments
Implementation Steps:
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Deploy new version to inactive environment (Green)
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Run smoke tests against Green
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Switch load balancer to Green
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Monitor for issues
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Keep Blue running for quick rollback
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After confidence period, Blue becomes next deployment target
Rollback: Switch load balancer back to Blue (seconds)
Canary Deployment
Gradually shift traffic from old version to new version.
Traffic Distribution Over Time:
T0: [====== v1.0 100% ======] T1: [=== v1.0 95% ===][v1.1 5%] T2: [== v1.0 75% ==][= v1.1 25% =] T3: [= v1.0 50% =][== v1.1 50% ==] T4: [====== v1.1 100% ======]
When to Use:
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High-risk deployments
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Need to validate with real traffic
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Want gradual rollout with monitoring
Traffic Progression (Example):
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5% for 15 minutes - validate basic functionality
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25% for 30 minutes - monitor error rates
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50% for 1 hour - check performance metrics
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100% - full rollout
Rollback Triggers:
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Error rate exceeds baseline + threshold
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Latency exceeds acceptable limits
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Health check failures
Rolling Deployment
Replace instances incrementally, one batch at a time.
Instance Pool (5 instances):
T0: [v1.0] [v1.0] [v1.0] [v1.0] [v1.0] T1: [v1.1] [v1.0] [v1.0] [v1.0] [v1.0] T2: [v1.1] [v1.1] [v1.0] [v1.0] [v1.0] T3: [v1.1] [v1.1] [v1.1] [v1.0] [v1.0] T4: [v1.1] [v1.1] [v1.1] [v1.1] [v1.0] T5: [v1.1] [v1.1] [v1.1] [v1.1] [v1.1]
When to Use:
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Limited infrastructure resources
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Can tolerate mixed versions during deployment
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Stateless applications
Configuration Parameters:
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maxUnavailable : How many instances can be down simultaneously
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maxSurge : How many extra instances during deployment
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minReadySeconds : Wait time before considering instance healthy
Feature Flags
Decouple deployment from release - deploy code without activating features.
Code deployed with feature flag:
if (featureFlags.isEnabled('new-checkout', user)) { return newCheckoutFlow(cart); } else { return legacyCheckoutFlow(cart); }
When to Use:
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Long-running feature development
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A/B testing requirements
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Gradual feature rollouts
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Kill switch for problematic features
Rollback: Disable flag (no deployment required)
Quality Gates
Required Gates
Every pipeline should include these gates:
Gate Threshold Block Deploy?
Unit Tests 100% pass Yes
Integration Tests 100% pass Yes
Code Coverage
= 80% Yes
Security Scan (Critical) 0 findings Yes
Security Scan (High) 0 new findings Configurable
Dependency Vulnerabilities 0 critical Yes
Manual Approval Gates
Use for production deployments:
Conceptual flow
stages:
- test
- deploy-staging
- approval # Manual gate
- deploy-prod
- verify
Approval Requirements:
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At least 2 approvers for production
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No self-approval allowed
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Time-boxed approval windows
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Audit trail of approvals
GitHub Actions Patterns
Basic Pipeline Structure
name: CI/CD Pipeline
on: push: branches: [main, develop] pull_request: branches: [main]
concurrency: group: ${{ github.workflow }}-${{ github.ref }} cancel-in-progress: true
jobs: build: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: actions/setup-node@v4 with: node-version: '20' cache: 'npm' - run: npm ci - run: npm run build - uses: actions/upload-artifact@v4 with: name: build path: dist/
test: needs: build runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: actions/download-artifact@v4 with: name: build path: dist/ - run: npm ci - run: npm test
deploy-staging: needs: test if: github.ref == 'refs/heads/main' environment: staging runs-on: ubuntu-latest steps: - uses: actions/download-artifact@v4 with: name: build - run: ./deploy.sh staging
deploy-prod: needs: deploy-staging if: github.ref == 'refs/heads/main' environment: production runs-on: ubuntu-latest steps: - uses: actions/download-artifact@v4 with: name: build - run: ./deploy.sh production
Matrix Builds
Run tests across multiple configurations:
jobs: test: strategy: fail-fast: false matrix: os: [ubuntu-latest, windows-latest, macos-latest] node: [18, 20, 22] runs-on: ${{ matrix.os }} steps: - uses: actions/checkout@v4 - uses: actions/setup-node@v4 with: node-version: ${{ matrix.node }} - run: npm ci - run: npm test
Reusable Workflows
Create reusable workflow in .github/workflows/deploy-reusable.yml :
name: Reusable Deploy
on: workflow_call: inputs: environment: required: true type: string secrets: DEPLOY_KEY: required: true
jobs: deploy: environment: ${{ inputs.environment }} runs-on: ubuntu-latest steps: - run: ./deploy.sh ${{ inputs.environment }} env: DEPLOY_KEY: ${{ secrets.DEPLOY_KEY }}
Call from another workflow:
jobs: deploy-staging: uses: ./.github/workflows/deploy-reusable.yml with: environment: staging secrets: DEPLOY_KEY: ${{ secrets.STAGING_DEPLOY_KEY }}
Environment Protection Rules
Configure in repository settings:
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Required reviewers for production
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Wait timer (e.g., 15 minutes before prod deploy)
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Restrict to specific branches
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Required status checks
GitLab CI Patterns
Basic Pipeline Structure
stages:
- build
- test
- deploy
variables: NODE_VERSION: "20"
default: image: node:${NODE_VERSION} cache: paths: - node_modules/
build: stage: build script: - npm ci - npm run build artifacts: paths: - dist/ expire_in: 1 hour
test:unit: stage: test script: - npm ci - npm run test:unit coverage: '/Coverage: \d+.\d+%/'
test:integration: stage: test services: - postgres:15 variables: POSTGRES_DB: test POSTGRES_USER: test POSTGRES_PASSWORD: test script: - npm ci - npm run test:integration
deploy:staging: stage: deploy environment: name: staging url: https://staging.example.com script: - ./deploy.sh staging only: - main
deploy:production: stage: deploy environment: name: production url: https://example.com script: - ./deploy.sh production when: manual only: - main
Pipeline Rules
deploy:production: rules: - if: $CI_COMMIT_BRANCH == "main" when: manual - if: $CI_COMMIT_TAG when: on_success - when: never
Include Templates
include:
- template: Security/SAST.gitlab-ci.yml
- template: Security/Dependency-Scanning.gitlab-ci.yml
- local: .gitlab/ci/deploy.yml
- project: 'devops/ci-templates' ref: main file: '/templates/docker-build.yml'
Dynamic Environments
deploy:review: stage: deploy environment: name: review/$CI_COMMIT_REF_SLUG url: https://$CI_COMMIT_REF_SLUG.review.example.com on_stop: stop:review script: - ./deploy.sh review only: - merge_requests
stop:review: stage: deploy environment: name: review/$CI_COMMIT_REF_SLUG action: stop script: - ./teardown.sh review when: manual only: - merge_requests
Rollback Mechanisms
Automated Rollback Triggers
Conceptual rollback configuration
rollback: triggers: - metric: error_rate threshold: 5% window: 5m - metric: latency_p99 threshold: 2000ms window: 5m - metric: health_check_failures threshold: 3 window: 1m action: type: previous_version notify: - slack: #deployments - pagerduty: on-call
Database Migration Rollback
Forward-only migrations (preferred):
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Never use destructive operations (DROP, DELETE)
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Add new columns as nullable
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Use feature flags to switch behavior
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Clean up old columns in later release
Rollback migrations:
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Every migration must have a corresponding rollback
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Test rollbacks in staging before production
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Keep rollback window defined (e.g., 24 hours)
Artifact-Based Rollback
rollback:production: stage: deploy environment: name: production script: - PREVIOUS_VERSION=$(get-previous-version.sh) - ./deploy.sh production $PREVIOUS_VERSION when: manual only: - main
Security Integration
SAST/DAST Integration
security:sast: stage: analyze image: security-scanner:latest script: - sast-scan --format sarif --output sast-results.sarif artifacts: reports: sast: sast-results.sarif
security:dependency: stage: analyze script: - npm audit --audit-level=high - trivy fs --security-checks vuln .
Secret Scanning
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Never commit secrets to repository
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Use environment secrets or vault integration
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Scan for exposed secrets in pre-commit hooks
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Rotate secrets immediately if exposed
Best Practices
Pipeline Design
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Keep pipelines under 15 minutes for main branch
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Use caching aggressively for dependencies
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Run expensive tests in parallel
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Fail fast with quick checks first
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Use artifacts to avoid rebuilding
Deployment Safety
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Always have a rollback plan
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Deploy to staging before production
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Use feature flags for risky changes
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Monitor deployments in real-time
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Document deployment procedures
Quality Assurance
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Enforce code coverage thresholds
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Block deployments on security findings
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Require peer approval for production
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Maintain environment parity
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Test rollback procedures regularly
Observability
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Log all deployment events
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Track deployment frequency and lead time
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Monitor change failure rate
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Measure mean time to recovery
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Alert on deployment failures
References
- templates/pipeline-template.md
- Complete pipeline template with all stages