Continuous Integration Best Practices

Continuous Integration means merging code frequently and validating each merge automatically. Good CI catches bugs early, enables confident refactoring, and keeps the main branch always releasable. This guide covers practical CI implementation.

CI Pipeline Stages

Pipeline Structure

Essential Stages

CI PIPELINE STAGES
══════════════════

STAGE 1: LINT & FORMAT
─────────────────────────────────────
Purpose: Consistent code style
Tools: ESLint, Prettier, Black, etc.
Time: <1 minute

Checks:
├── Code formatting
├── Style rules
├── Import ordering
├── No unused variables
└── Catch issues before review

STAGE 2: UNIT TESTS
─────────────────────────────────────
Purpose: Logic verification
Tools: Jest, PyTest, JUnit, etc.
Time: <5 minutes

Run:
├── All unit tests
├── Fast, isolated tests
├── No external dependencies
├── High coverage areas
└── Quick feedback

STAGE 3: BUILD
─────────────────────────────────────
Purpose: Verify compilation
Tools: Webpack, tsc, cargo, etc.
Time: <3 minutes

Verify:
├── Code compiles
├── Dependencies resolve
├── Assets generated
├── Build artifacts created
└── Can produce output

STAGE 4: INTEGRATION TESTS
─────────────────────────────────────
Purpose: Component interaction
Tools: Test frameworks + test DB/services
Time: <10 minutes

Test:
├── API endpoints
├── Database operations
├── Service interactions
├── Key flows
└── Realistic scenarios

STAGE 5: SECURITY SCAN
─────────────────────────────────────
Purpose: Find vulnerabilities
Tools: Snyk, OWASP, npm audit, etc.
Time: <5 minutes

Scan:
├── Dependency vulnerabilities
├── Code security issues
├── Secret detection
├── License compliance
└── Security gates

Pipeline Configuration

EXAMPLE CI CONFIGURATION
════════════════════════

GITHUB ACTIONS EXAMPLE:
─────────────────────────────────────
name: CI
on: [push, pull_request]

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - run: npm ci
      - run: npm run lint

  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - run: npm ci
      - run: npm test

  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - run: npm ci
      - run: npm run build

  integration:
    runs-on: ubuntu-latest
    needs: [lint, test, build]
    steps:
      - uses: actions/checkout@v3
      - run: npm ci
      - run: npm run test:integration

PARALLEL EXECUTION:
─────────────────────────────────────
├── Lint, Test, Build run in parallel
├── Integration runs after all pass
├── Faster overall pipeline
├── Early failure, early feedback
└── Optimize for speed

Fast Feedback

Speed Matters

CI SPEED OPTIMIZATION
═════════════════════

WHY SPEED MATTERS:
─────────────────────────────────────
Slow CI:
├── Developers wait
├── Switch to other work
├── Context switch cost
├── Batch up changes
├── Find issues late
└── Frustration

Fast CI:
├── Immediate feedback
├── Fix while context fresh
├── More frequent commits
├── Catch issues early
├── Developer happiness
└── Higher quality

SPEED TARGETS:
─────────────────────────────────────
├── Lint: <1 minute
├── Unit tests: <5 minutes
├── Full pipeline: <10 minutes
├── Absolute max: 15 minutes
└── Faster is better

OPTIMIZATION STRATEGIES:
─────────────────────────────────────
Caching:
├── Cache dependencies
├── Cache build artifacts
├── Cache test fixtures
├── Reuse what doesn't change
└── Significant speedup

Parallelization:
├── Run independent stages parallel
├── Split test suites
├── Multiple runners
├── Reduce wall-clock time
└── Use available resources

Test optimization:
├── Fast unit tests (most)
├── Fewer integration tests
├── Slowest tests last
├── Skip unchanged areas
└── Testing pyramid

Maintaining Green

Always Releasable

KEEPING CI GREEN
════════════════

RULE: FIX BROKEN BUILDS IMMEDIATELY
─────────────────────────────────────
When CI fails:
├── Stop other work
├── Fix immediately
├── Or revert the change
├── Team's top priority
└── Broken build = blocked team

RESPONSIBILITY:
─────────────────────────────────────
Who broke it fixes it:
├── Your commit, your fix
├── Fast response
├── Don't leave for later
├── Don't ignore
└── Ownership

AVOID BROKEN BUILDS:
─────────────────────────────────────
Prevention:
├── Run tests locally first
├── Small, frequent commits
├── Thorough code review
├── Pre-commit hooks
└── Catch before push

Pre-commit:
├── Lint check
├── Format check
├── Quick unit tests
├── Catch obvious issues
└── Faster feedback

GREEN = RELEASABLE:
─────────────────────────────────────
Main branch should always be:
├── Buildable
├── Tests passing
├── Deployable
├── Production-ready
└── Ship any time

Integration Frequency

Merge Often

FREQUENT INTEGRATION
════════════════════

MERGE DAILY (AT LEAST):
─────────────────────────────────────
Best practice:
├── Multiple merges per day
├── Small changes each time
├── Never more than 1 day without merge
├── Long branches = integration problems
└── Continuous means continuous

SMALL CHANGES:
─────────────────────────────────────
Benefits of small:
├── Easier to review
├── Less likely to conflict
├── Problems isolated
├── Easy to revert
├── Faster feedback
└── Lower risk

FEATURE FLAGS:
─────────────────────────────────────
Merge incomplete features:
├── Code deployed but inactive
├── Flag controls visibility
├── Integrate continuously
├── Enable when ready
└── Decouple deploy from release

Example:
├── Merge auth code (flag off)
├── Continue development
├── Keep integrating
├── Enable flag when complete
├── Users never see incomplete

Quality Gates

Required Checks

CI QUALITY GATES
════════════════

REQUIRED FOR MERGE:
─────────────────────────────────────
☐ All tests passing
☐ Lint clean
☐ Build succeeds
☐ Coverage threshold met
☐ Security scan clean
☐ Code review approved
└── All must pass to merge

BRANCH PROTECTION:
─────────────────────────────────────
GitHub settings:
├── Require status checks
├── Require up-to-date branches
├── Require review approval
├── No force push to main
├── No direct commits to main
└── Enforce quality

COVERAGE THRESHOLDS:
─────────────────────────────────────
Set minimum:
├── 80% overall coverage
├── No decrease from baseline
├── New code must be covered
├── Fail build if below
└── Maintain quality over time

SECURITY GATES:
─────────────────────────────────────
├── No critical vulnerabilities
├── No high without exception
├── Known CVE blocking
├── Secret detection
└── Security non-negotiable

GitScrum CI Integration

Connected Workflow

GITSCRUM + CI INTEGRATION
═════════════════════════

LINK TO TASKS:
─────────────────────────────────────
PR linked to task:
├── CI status visible on task
├── Auto-update on CI completion
├── Merge → Task status update
└── Connected context

AUTOMATED TRANSITIONS:
─────────────────────────────────────
CI events trigger:
├── PR merged → Task to "Done"
├── CI failed → Alert on task
├── Deploy complete → Notify
└── Workflow automation

VISIBILITY:
─────────────────────────────────────
Dashboard:
├── CI status widget
├── Failed builds visible
├── Deploy status
├── Team awareness
└── Problems surface quickly

COMMIT LINKING:
─────────────────────────────────────
Commit message: "GS-123: Add login"
├── Links to task automatically
├── Progress visible
├── History tracked
└── Traceability

Best Practices

For CI

1. Fast pipelines — Under 10 minutes
2. Fix immediately — Broken builds are priority 1
3. Merge frequently — Daily minimum
4. Quality gates — Required checks before merge
5. Green always — Main is always releasable

Anti-Patterns

CI MISTAKES:
✗ Slow pipelines (30+ minutes)
✗ Ignoring failures
✗ Long-running branches
✗ Skipping tests
✗ No branch protection
✗ Manual deployments
✗ Flaky tests tolerated
✗ "Works on my machine"

Related Solutions

• Streamlining code review processes
• Quality assurance best practices
• Workflow automation in GitScrum