lab-11

Lab 11 - Blue / green deployments

Task 0: Creating a namespace

Create a namespace for this lab:

kubectl create ns lab-11

---

namespace "lab-11" created

Task 1: Blue / green deployment

For this task we are creating 2 versions of 1 deployment. This means that we can use the service to point to either of the deployments. This can be used for example if you want to update your application. We are going to use the container-info application again to demo this feature.

First we will create a blue deployment. This is the first and initial version of our application.

Create a file lab-11-deployment-blue.yml with the following content.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: container-info-blue
  labels:
    app: container-info
spec:
  replicas: 3
  selector:
    matchLabels:
      app: container-info
  template:
    metadata:
      labels:
        app: container-info
        version: "blue"
    spec:
      containers:
      - name: container-info
        image: gluobe/container-info:blue
        ports:
        - containerPort: 80

As you can see we have added a new label called version with this label we can select the correct deployment in the service we are creating in this task.

kubectl apply -f lab-11-deployment-blue.yml -n lab-11

---

deployment.apps/container-info-blue created

Now create the file lab-11-service-blue-green.yml with the following content.

kind: Service
apiVersion: v1
metadata:
  name: container-info
spec:
  selector:
    app: container-info
    version: "blue"
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: NodePort

Notice that in the spec:selector:version we chose for blue this specifies the version of the deployment we are going to expose.

kubectl apply -f lab-11-service-blue-green.yml -n lab-11

---

service/container-info created

Confirm that the application is running by doing to following command.

minikube service container-info -n lab-11

You will see that our blue version of the deployment is now running on our minikube instance.

After you exposed the blue version we are going to create a green version of the application. This is done by creating a file lab-11-deployment-green.yml with the following content.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: container-info-green
  labels:
    app: container-info
spec:
  replicas: 3
  selector:
    matchLabels:
      app: container-info
  template:
    metadata:
      labels:
        app: container-info
        version: "green"
    spec:
      containers:
      - name: container-info
        image: gluobe/container-info:green
        ports:
        - containerPort: 80

We changed some parameters from blue to green, notice that the image changed as well. We are now deploying a green version.

kubectl apply -f lab-11-deployment-green.yml -n lab-11

---

deployment.apps/container-info-green created

If you list the deployments in your namespace you will see that we now have 2 deployments.

kubectl get deployment -n lab-11

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NAME                   DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
container-info-blue    3         3         3            3           12m
container-info-green   3         3         3            3           12m

A blue and a green version. Remember that our service is still pointing at the blue version. In the next step we will update the service in a way that it will point to the green version of our deployment.

Edit the lab-11-service-blue-green.yml file with the content below. You can also just clear the file and copy the following content.

kind: Service
apiVersion: v1
metadata:
  name: container-info
spec:
  selector:
    app: container-info
    version: "green"
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: NodePort

The only thing that is updated in this file is basically the version this is set to green now.

kubectl apply -f lab-11-service-blue-green.yml -n lab-11

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service/container-info configured

Now you can run the service command again to check your newly updated version of the deployment.

minikube service container-info -n lab-11

We can now delete the blue deployment:

kubectl delete -f lab-11-deployment-blue.yml -n lab-11

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deployment.apps "container-info-blue" deleted

You now only have one deployment running, the green:

kubectl get deployment -n lab-11

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NAME                   READY   UP-TO-DATE   AVAILABLE   AGE
container-info-green   3/3     3            3           3m31s

Congratulations, you have successfully performed you first blue / green deployment on minikube!

Task 2: Cleanup

Clean up the namespace for this lab:

kubectl delete ns lab-11

---

namespace "lab-11" deleted