deploy-strategies

Deploy Strategies

Implement safe, zero-downtime deployment strategies with proper rollback procedures, traffic shifting, and health monitoring.

When to Use

• User asks about zero-downtime deployments
• User needs to choose between deployment strategies
• User asks about canary releases or blue-green deploys
• User implements feature flags for gradual rollout
• User needs rollback procedures

Core Patterns

Blue-Green Deployment

Maintain two identical production environments. Route traffic to the new one after verification, keep the old one as instant rollback.

# Kubernetes blue-green with service switching
apiVersion: v1
kind: Service
metadata:
  name: api
spec:
  selector:
    app: api
    version: green      # Switch to "blue" for rollback
  ports:
    - port: 80
      targetPort: 3000
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: api-green
spec:
  replicas: 3
  selector:
    matchLabels:
      app: api
      version: green
  template:
    metadata:
      labels:
        app: api
        version: green
    spec:
      containers:
        - name: api
          image: myapp:2.0.0
          readinessProbe:
            httpGet:
              path: /health
              port: 3000
            initialDelaySeconds: 5
            periodSeconds: 5

# Blue-green deploy script
deploy_blue_green() {
  local NEW_VERSION=$1
  local CURRENT=$(kubectl get svc api -o jsonpath='{.spec.selector.version}')
  local TARGET=$( [ "$CURRENT" = "blue" ] && echo "green" || echo "blue" )

  # Deploy new version to inactive slot
  kubectl set image "deployment/api-${TARGET}" "api=myapp:${NEW_VERSION}"
  kubectl rollout status "deployment/api-${TARGET}" --timeout=300s

  # Run smoke tests against new deployment
  kubectl run smoke-test --rm -i --image=curlimages/curl -- \
    curl -f "http://api-${TARGET}.default.svc/health"

  # Switch traffic
  kubectl patch svc api -p "{\"spec\":{\"selector\":{\"version\":\"${TARGET}\"}}}"
  echo "Traffic switched to ${TARGET} (v${NEW_VERSION})"
}