Kubernetesにおける高度なCI/CD: Blue-GreenデプロイメントとCanaryリリース

                       User Ingress / Load Balancer
                                     │
                      [ Active Service Selector ]
                                     │
                     ┌───────────────┴───────────────┐
                     ▼ (100% traffic)                ▼ (0% traffic)
              [ Blue Pods v1.2 ]              [ Green Pods v1.3 ]

Step 1 (Expand): Add nullable column or new table. Deploy DB migration.
Step 2 (Deploy): Green version uses new column, Blue version ignores it.
Step 3 (Cutover): Route traffic to Green.
Step 4 (Contract): Drop old deprecated columns after Blue is destroyed.

Incoming Traffic ───► Ingress / Service Mesh (Istio / NGINX / ALB)
                            │
            ┌───────────────┴───────────────┐
            ▼ (95% Live Traffic)            ▼ (5% Canary Traffic)
     [ Stable Service ]              [ Canary Service ]
            │                               │
     [ Stable Pods v1 ]              [ Canary Pods v2 ]
                                            │
                                            ▼
                                [ Prometheus Query Engine ]
                           (Error rate < 0.5%, p99 latency < 200ms)
                                     │              │
                              [ PASS: +20% ]   [ FAIL: Abort & Rollback ]

apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: payments-api
  namespace: production
spec:
  replicas: 10
  revisionHistoryLimit: 5
  selector:
    matchLabels:
      app: payments-api
  template:
    metadata:
      labels:
        app: payments-api
    spec:
      containers:
        - name: payments-api
          image: ghcr.io/my-org/payments-api:v2.4.0
          ports:
            - containerPort: 8080
          resources:
            requests:
              cpu: 500m
              memory: 512Mi
  strategy:
    canary:
      canaryService: payments-api-canary
      stableService: payments-api-stable
      trafficRouting:
        nginx:
          stableIngress: payments-api-ingress
      steps:
        # Step 1: Route 5% traffic to canary and pause 10 minutes
        - setWeight: 5
        - pause: { duration: 10m }
        # Step 2: Run automated Prometheus analysis
        - analysis:
            templates:
              - templateName: http-error-rate-check
        # Step 3: Increase traffic to 20%
        - setWeight: 20
        - pause: { duration: 30m }
        # Step 4: Increase traffic to 50%
        - setWeight: 50
        - pause: { duration: 15m }

apiVersion: argoproj.io/v1alpha1
kind: AnalysisTemplate
metadata:
  name: http-error-rate-check
  namespace: production
spec:
  metrics:
    - name: success-rate
      interval: 1m
      successCondition: result[0] >= 0.995 # Must maintain 99.5% success rate
      failureLimit: 3                      # Abort after 3 consecutive failed probes
      provider:
        prometheus:
          address: http://prometheus-k8s.monitoring:9090
          query: |
            sum(rate(http_requests_total{app="payments-api", status=~"2..|3.."}[2m]))
            /
            sum(rate(http_requests_total{app="payments-api"}[2m]))

    - name: p99-latency
      interval: 1m
      successCondition: result[0] <= 0.250 # Latency must stay under 250ms
      failureLimit: 2
      provider:
        prometheus:
          address: http://prometheus-k8s.monitoring:9090
          query: |
            histogram_quantile(0.99, sum(rate(http_request_duration_seconds_bucket{app="payments-api"}[2m])) by (le))