DevOps Excellence

Core Principles

• Shift Left — Address security and quality early in SDLC
• GitOps — Git as single source of truth for infrastructure and deployments
• Infrastructure as Code — All infrastructure versioned and reproducible
• Progressive Delivery — Gradual rollouts with feature flags and canary releases
• Immutable Infrastructure — Replace, don't modify running systems
• Observability-First — Monitor metrics tied to deployments and features
• Policy as Code — Enforce compliance and security automatically
• Platform Engineering — Build golden paths and self-service portals

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Hard Rules (Must Follow)

These rules are mandatory. Violating them means the skill is not working correctly.

No Static Credentials

Never use long-lived static credentials. Always use OIDC or short-lived tokens.

# ❌ FORBIDDEN: Static AWS credentials
env:
  AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
  AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}

# ✅ REQUIRED: OIDC-based authentication
- name: Configure AWS Credentials
  uses: aws-actions/configure-aws-credentials@v4
  with:
    role-to-assume: arn:aws:iam::123456789012:role/GitHubActions
    aws-region: us-east-1
    # No long-lived secrets - uses GitHub OIDC provider

No Root Containers

Containers must NEVER run as root. Always specify a non-root user.

# ❌ FORBIDDEN: Running as root (default)
FROM node:20
WORKDIR /app
CMD ["node", "server.js"]

# ❌ FORBIDDEN: Explicit root user
USER root

# ✅ REQUIRED: Non-root user with UID > 1000
FROM node:20-alpine
RUN addgroup -g 1001 -S nodejs && \
    adduser -S nodejs -u 1001
USER nodejs
WORKDIR /app
CMD ["node", "server.js"]

No Secrets in Images

Never bake secrets into Docker images. Use runtime injection or secrets managers.

# ❌ FORBIDDEN: Secrets in build args or ENV
ARG DATABASE_PASSWORD
ENV API_KEY=sk-xxx

# ❌ FORBIDDEN: Copying secret files
COPY .env /app/.env
COPY credentials.json /app/

# ✅ REQUIRED: Mount secrets at runtime
# docker run -v /secrets:/app/secrets:ro myapp
# Or use Kubernetes secrets/configmaps

Protected Production Deployments

Production deployments must require approval and be restricted to main branch.

# ❌ FORBIDDEN: Direct production deploy without protection
deploy:
  runs-on: ubuntu-latest
  steps:
    - run: deploy-to-prod.sh

# ✅ REQUIRED: Environment protection
deploy:
  runs-on: ubuntu-latest
  environment:
    name: production
    url: https://myapp.com
  # Requires: approval + main branch only

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Quick Reference

When to Use What

Scenario	Tool/Pattern	Reason
Public GitHub project	GitHub Actions	Native integration, free for public repos
Enterprise GitLab	GitLab CI	Unified platform, advanced security scanning
Multi-cloud IaC	Terraform	Mature ecosystem, wide provider support
Developer-centric IaC	Pulumi	Real programming languages, better testing
Kubernetes deployments	ArgoCD + Kustomize	GitOps standard, declarative config
Zero-downtime releases	Blue-Green or Canary	Instant rollback capability
Gradual feature rollout	Feature flags (LaunchDarkly)	Progressive delivery with targeting

Deployment Strategy Selection

Strategy	Downtime	Cost	Rollback Speed	Complexity	Best For
Rolling	Minimal	Low	Medium	Low	Regular updates, cost-conscious
Blue-Green	Zero	High (2x)	Instant	Medium	Critical systems, easy rollback
Canary	Zero	Medium	Fast	High	Risk mitigation, data-driven
Recreate	High	Low	N/A	Very Low	Non-critical, dev/test only

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CI/CD Pipeline Best Practices

Pipeline Security

# Short-lived credentials (not static keys)
- name: Configure AWS Credentials
  uses: aws-actions/configure-aws-credentials@v4
  with:
    role-to-assume: arn:aws:iam::123456789012:role/GitHubActions
    aws-region: us-east-1
    # OIDC provider - no long-lived secrets!

# Protected environments for production
environment:
  name: production
  # Requires approval + restricts to main branch

Speed Optimization

• 10-minute build rule — Most projects should build in <10 minutes
• Parallel jobs — Run tests, linting, security scans concurrently
• Cache dependencies — Cache node_modules, .m2, pip packages
• Conditional execution — Skip jobs when files haven't changed

# Example: conditional job execution
jobs:
  backend-tests:
    if: contains(github.event.head_commit.modified, 'backend/')
    runs-on: ubuntu-latest

Testing Pyramid

              /\
             /E2E\        <- Few (slow, expensive)
            /------\
           /Integration\ <- Some (medium speed)
          /------------\
         /  Unit Tests  \ <- Many (fast, cheap)
        /----------------\

• 70% Unit tests (fast, isolated)
• 20% Integration tests (service interactions)
• 10% E2E tests (full user workflows)

Security Scanning Integration

# Multi-layer security scanning
jobs:
  security:
    runs-on: ubuntu-latest
    steps:
      # SAST - Static code analysis
      - uses: github/codeql-action/init@v3

      # SCA - Dependency vulnerabilities
      - name: Run Trivy
        uses: aquasecurity/trivy-action@master
        with:
          scan-type: 'fs'
          format: 'sarif'

      # Secret scanning
      - name: Gitleaks
        uses: gitleaks/gitleaks-action@v2

      # Container scanning
      - name: Scan Docker image
        run: trivy image myapp:${{ github.sha }}

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Docker Best Practices

Multi-Stage Builds

# Build stage - includes build tools (900MB+)
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production

# Runtime stage - minimal image (<100MB)
FROM node:20-alpine AS runtime
RUN addgroup -g 1001 -S nodejs && \
    adduser -S nodejs -u 1001
WORKDIR /app
COPY --from=builder --chown=nodejs:nodejs /app/node_modules ./node_modules
COPY --chown=nodejs:nodejs . .
USER nodejs
EXPOSE 3000
CMD ["node", "server.js"]

Security Hardening

• Non-root user — ALWAYS run as non-root (UID 1001)
• Minimal base images — Use alpine, distroless, or scratch
• Read-only filesystem — docker run --read-only
• No secrets in layers — Use build secrets or external vaults
• Resource limits — Set CPU/memory limits to prevent DoS
• Signed images — Enable Docker Content Trust

# Security best practices example
FROM gcr.io/distroless/nodejs20-debian12
COPY --chown=65532:65532 /app /app
USER 65532
EXPOSE 8080

.dockerignore

# Version control
.git
.gitignore

# Dependencies (install fresh in container)
node_modules
vendor/
*.pyc
__pycache__

# Secrets and configs
.env
.env.local
secrets/
*.key
*.pem

# Development files
README.md
Dockerfile
docker-compose.yml
.vscode/
.idea/

# Testing and CI
tests/
*.test.js
.github/

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Kubernetes Deployment Patterns

Resource Management (Right-Sizing)

# 99.94% of clusters are over-provisioned!
# Average CPU usage: 10%, Memory: 23%
resources:
  requests:
    memory: "128Mi"  # Guaranteed allocation
    cpu: "100m"      # 0.1 CPU cores
  limits:
    memory: "256Mi"  # Maximum allowed
    cpu: "200m"      # Hard cap

# Use tools: Kubecost, Goldilocks, VPA

Health Checks

# Liveness: Is container alive?
livenessProbe:
  httpGet:
    path: /health
    port: 8080
  initialDelaySeconds: 30
  periodSeconds: 10
  timeoutSeconds: 5
  failureThreshold: 3

# Readiness: Can it receive traffic?
readinessProbe:
  httpGet:
    path: /ready
    port: 8080
  initialDelaySeconds: 5
  periodSeconds: 5
  successThreshold: 1

# Startup: Has initialization completed?
startupProbe:
  httpGet:
    path: /startup
    port: 8080
  failureThreshold: 30  # 30*10s = 5min for slow starts
  periodSeconds: 10

ConfigMaps and Secrets

# Group related resources in single manifest
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  APP_ENV: production
  LOG_LEVEL: info
---
apiVersion: v1
kind: Secret
metadata:
  name: app-secrets
type: Opaque
stringData:
  DATABASE_URL: postgresql://user:pass@db:5432/mydb
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  template:
    spec:
      containers:
      - name: app
        envFrom:
        - configMapRef:
            name: app-config
        - secretRef:
            name: app-secrets

Security Best Practices

# Pod Security Standards
securityContext:
  runAsNonRoot: true
  runAsUser: 1000
  fsGroup: 1000
  seccompProfile:
    type: RuntimeDefault
  capabilities:
    drop:
    - ALL

# Network Policies (deny-by-default)
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: deny-all-ingress
spec:
  podSelector: {}
  policyTypes:
  - Ingress

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Extended Reference

Detailed material starting at ## Infrastructure as Code (Terraform/Pulumi) has been moved to reference/extended.md to keep this skill concise. Load that reference when the task requires the moved examples, command catalogs, checklists, platform details, or implementation templates.