Blue-green deployment

Ce este blue-green deployment?

Blue-green deployment are următoarele caracteristici:

două medii identice
switch instant de trafic
rollback foarte rapid (switch înapoi)
zero downtime

Cum funcționează?

Pașii sunt următorii:

Deploy Green (în paralel cu Blue)
Testează Green (fără rularea pe producție)
Switch trafic Blue → Green
(opțional) Ține Blue pentru rollback rapid

Task

Mai jos aveți trei fișiere și executați comenzile de mai jos:

service.yaml:

apiVersion: v1
kind: Service
metadata:
  name: web-app-service
  labels:
    app: web-app
spec:
  type: LoadBalancer
  ports:
  - port: 80
    targetPort: 80
  selector:
    app: web-app
    env: blue  # ← Initial point la BLUE

blue-deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: blue-deployment
  labels:
    app: web-app
    env: blue
spec:
  replicas: 3
  selector:
    matchLabels:
      app: web-app
      env: blue
  template:
    metadata:
      labels:
        app: web-app
        env: blue
        version: "1"
    spec:
      containers:
      - name: web
        image: nginx:1.21
        ports:
        - containerPort: 80
        volumeMounts:
        - name: html
          mountPath: /usr/share/nginx/html
      volumes:
      - name: html
        configMap:
          name: blue-config
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: blue-config
data:
  index.html: |
    <html>
    <head><title>BLUE Environment</title></head>
    <body style="background:#2196F3; color:white; font-size:2em; padding:50px">
      <h1>🔵 BLUE Environment</h1>
      <h2>Version 1.0</h2>
      <p>This is the production environment</p>
    </body>
    </html>

green-deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: green-deployment
  labels:
    app: web-app
    env: green
spec:
  replicas: 3
  selector:
    matchLabels:
      app: web-app
      env: green
  template:
    metadata:
      labels:
        app: web-app
        env: green
        version: "2"
    spec:
      containers:
      - name: web
        image: nginx:1.21
        ports:
        - containerPort: 80
        volumeMounts:
        - name: html
          mountPath: /usr/share/nginx/html
      volumes:
      - name: html
        configMap:
          name: green-config
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: green-config
data:
  index.html: |
    <html>
    <head><title>GREEN Environment</title></head>
    <body style="background:#4CAF50; color:white; font-size:2em; padding:50px">
      <h1>🟢 GREEN Environment</h1>
      <h2>Version 2.0</h2>
      <p>This is the new version!</p>
      <p>Ready for production</p>
    </body>
    </html>

executați comenzile de mai jos, folosind fișierele de mai sus:

# STEP 1: Deploy environment-ul BLUE (versiunea actuală)

kubectl apply -f blue-deployment.yaml
kubectl apply -f service.yaml

# Observă pod-urile BLUE:
kubectl get pods -l env=blue

# STEP 2: Testeaza BLUE (Production)

# Obține URL-ul:
BLUE_URL=http://localhost
echo "BLUE URL: $BLUE_URL"

curl $BLUE_URL

# Ar trebui să vezi "BLUE Environment - Version 1.0".

# STEP 3: Deploy Environment-ul GREEN (noua versiune)

# IMPORTANT: GREEN rulează în paralel, dar NU primește trafic încă.

kubectl apply -f green-deployment.yaml

# Verificăm ambele versiuni:
kubectl get deployments blue-deployment green-deployment
kubectl get pods -l app=web-app

# Output:
# blue-deployment-pod1    1/1   Running   ← Receives traffic
# blue-deployment-pod2       1/1   Running   ← Receives traffic
# blue-deployment-pod3      1/1   Running   ← Receives traffic
# green-deployment-pod1     1/1   Running   ← NO TRAFFIC yet
# green-deployment-pod2     1/1   Running   ← NO TRAFFIC yet
# green-deployment-pod3     1/1   Running   ← NO TRAFFIC yet

# Observa: 6 pod-uri rulează, dar doar 3 (BLUE) primesc trafic.

# STEP 4: Testeaza GREEN Direct (fără Service)

# Pentru a testa GREEN înainte de switch, accesează pod-ul direct:

kubectl port-forward $(kubectl get pod -l env=green -o jsonpath='{.items[0].metadata.name}') 8080:80 # aceasta comanda o sa blocheze terminalul curent

curl http://localhost:8080

# Ar trebui să vezi "GREEN Environment - Version 2.0".

STEP 5: SWITCH TRAFIC: BLUE → GREEN

# Schimbăm selector-ul service-ului:

kubectl patch service web-app-service -p '{"spec":{"selector":{"app":"web-app","env":"green"}}}'

# STEP 6: Observă switch-ul instant

# Testează imediat:
curl $BLUE_URL

# ar trebui să vezi imediat "GREEN Environment"!

# Observam:
# - Zero downtime
# - Switch instant
# - BLUE încă rulează (poate fi folosit pentru rollback)


# STEP 8: Rollback: switch înapoi la BLUE

kubectl patch service web-app-service -p '{"spec":{"selector":{"app":"web-app","env":"blue"}}}'
curl $BLUE_URL

# CLEANUP

kubectl delete deployment blue-deployment green-deployment
kubectl delete service web-app-service
kubectl delete configmap blue-config green-config

Ce este blue-green deployment?​

Cum funcționează?​

Ce este blue-green deployment?

Cum funcționează?