Blue Green Deployment in Openshift

Openshift is a platform for running containerized application workloads which is developed by Red Hat.

Here i am going to explain how we can utilize blue green deployment in openshift.

i have openshift services deployed one is blue and another is green container

Blue Version has old code and Green Version has new code.

Below is the blue version openshift yaml

Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  namespace: bitroid-dev
  name: fastapiwebhook-blue
  annotations: {}
spec:
  selector:
    matchLabels:
      app: fastapiwebhook-blue
  replicas: 2
  template:
    metadata:
      labels:
        app: fastapiwebhook-blue
    spec:
      containers:
        - name: container
          image: 'quay.io/hemanth22/fastapiwebhook-blue:latest'
          ports:
            - containerPort: 8080
              protocol: TCP
          env: []
      imagePullSecrets: []
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
  paused: false

Service

apiVersion: v1
kind: Service
metadata:
  name: fastapiwebhook-blue
  namespace: bitroid-dev
spec:
  selector:
    app: fastapiwebhook-blue
  ports:
    - protocol: TCP
      port: 8000
      targetPort: 8000

Below is the green version openshift yaml

Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  namespace: bitroid-dev
  name: fastapiwebhook-green
  annotations: {}
spec:
  selector:
    matchLabels:
      app: fastapiwebhook-green
  replicas: 2
  template:
    metadata:
      labels:
        app: fastapiwebhook-green
    spec:
      containers:
        - name: container
          image: 'quay.io/hemanth22/fastapiwebhook-green:latest'
          ports:
            - containerPort: 8080
              protocol: TCP
          env: []
      imagePullSecrets: []
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
  paused: false

Service

apiVersion: v1
kind: Service
metadata:
  name: fastapiwebhook-green
  namespace: bitroid-dev
spec:
  selector:
    app: fastapiwebhook-green
  ports:
    - protocol: TCP
      port: 8000
      targetPort: 8000

Create the route with below yaml file.

kind: Route
apiVersion: route.openshift.io/v1
metadata:
  name: fastapiwebhook
  namespace: bitroid-dev
  labels: {}
spec:
  to:
    kind: Service
    name: fastapiwebhook-blue
    weight: 100
  alternateBackends:
    - weight: 0
      kind: Service
      name: fastapiwebhook-green
  port:
    targetPort: 8000
  tls: {}
  path: /

Once route is created, based on the weight first traffic as showing below, it will hit to service: fastapiwebhook-blue

Below is the sample output where webhook request hit to fastapiwebhook-blue

Now traffic weight has been update to 100 , for service : fastapiwebhook-green

Now traffic will server to green service: fastapiwebhook-green

if you see below, webhook request traffc has been routed green service: fastapiwebhook-green

This is blue green strategy in openshift, this helps if green version is unstable, it is easier to fall back to blue version.