Sample minimal blue/green deployment strategy codes used on cafebazaar.ir

0-blue-green-deployment.sh

# this is a minimal sample code used for ci pipelines to implement blue/green deployment

1-deploy-staging.sh

#!/usr/bin/env bash
SERVICE=barista

set -e

CURRENT_PRODUCTION_VERSION=$(kubectl get service ${SERVICE}-production -o jsonpath='{.spec.selector.version}')
[[ ${CURRENT_PRODUCTION_VERSION} = green ]] && NEXT_VERSION="blue" || NEXT_VERSION="green"
echo "Current production version is ${CURRENT_PRODUCTION_VERSION}"
echo "Current staging version is $(kubectl get service ${SERVICE}-staging -o jsonpath='{.spec.selector.version}'
echo "Staging will become ${NEXT_VERSION}"

IMAGE_PATH=${CI_REGISTRY}/${GIT_GROUP}/${SERVICE}:${CI_COMMIT_SHA}
echo "Image Path is: ${IMAGE_PATH}"

# set docker image of staging deployment
DEPLOYMENT_NAME=${SERVICE}-${NEXT_VERSION}
kubectl set image deployment/${DEPLOYMENT_NAME} ${SERVICE}=${IMAGE_PATH}

# ensure there's at least one pod running for staging deployment (will be zero after deploy-production)
kubectl scale deployment/${DEPLOYMENT_NAME} --replicas=1

set +e
while : ; do
    sleep 3
    READY=$(kubectl get deployments ${DEPLOYMENT_NAME} -o jsonpath='{.status.conditions[?(@.reason=="MinimumReplicasAvailable")].status}')
    [[ "$READY" != "True" ]] || break
done

# ensure staging service routes to this staging deployment
kubectl patch svc ${SERVICE}-staging -p "{\"spec\":{\"selector\": {\"app\": \"${SERVICE}\", \"version\": \"${NEXT_VERSION}\"}}}"

echo "Staging became ${NEXT_VERSION}"
echo "Test staging then trigger next step manually through gitlab"

2-deploy-production.sh

#!/usr/bin/env bash
SERVICE=barista
REPLICA_COUNT=3

OLD_PRODUCTION_VERSION=$(kubectl get service ${SERVICE}-production -o jsonpath='{.spec.selector.version}')
CURRENT_STAGING_VERSION=$(kubectl get service ${SERVICE}-staging -o jsonpath='{.spec.selector.version}')
echo "Staging is ${CURRENT_STAGING_VERSION}"

# decrease old production replicas to 1
kubectl scale deployment/${SERVICE}-${OLD_PRODUCTION_VERSION} --replicas=1

# route production service to our new deployment (previously staging)
kubectl patch svc "${SERVICE}-production" -p "{\"spec\":{\"selector\": {\"app\": \"${SERVICE}\", \"version\": \"${CURRENT_STAGING_VERSION}\"}}}"

# increase new production replicas
kubectl scale deployment/${SERVICE}-${CURRENT_STAGING_VERSION} --replicas=${REPLICA_COUNT}

sleep 5 # wait a little for new pods to be running

# no staging pods needed anymore (till next deploy-staging)
kubectl scale deployment/${SERVICE}-${OLD_PRODUCTION_VERSION} --replicas=0

echo "Production became ${CURRENT_STAGING_VERSION}"

blue-deployment.yml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: barista-blue
spec:
  replicas: 5
  selector:
    matchLabels:
      app: barista
  template:
    metadata:
      labels:
        app: barista
        version: blue
    spec:
      containers:
      - name: barista
        image: # our internal docker registry url
        ports:
        - containerPort: 80

green-deployment.yml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: barista-green
spec:
  replicas: 5
  selector:
    matchLabels:
      app: barista
  template:
    metadata:
      labels:
        app: barista
        version: green
    spec:
      containers:
      - name: barista
        image: # our internal docker registry url
        ports:
        - containerPort: 80

production-ingress.yml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: barista-production
spec:
  tls:
  - hosts:
    - cafebazaar.ir

  rules:
  - host: cafebazaar.ir
    http:
      paths:
      - backend:
          serviceName: barista-production
          servicePort: 80
        path: /

production-service.yml

apiVersion: v1
kind: Service
metadata:
  name: barista-production
  labels:
    name: barista-production
spec:
  ports:
  - port: 80
    targetPort: 80
  selector:
    app: barista
    version: green

staging-ingress.yml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: barista-staging
spec:
  tls:
  - hosts:
    - staging.xyz

  rules:
  - host: staging.xyz
    http:
      paths:
      - backend:
          serviceName: barista-staging
          servicePort: 80
        path: /

staging-service.yml

apiVersion: v1
kind: Service
metadata:
  name: barista-staging
  labels:
    name: barista-staging
spec:
  ports:
  - port: 80
    targetPort: 80
  selector:
    app: barista
    version: blue