Blue Green Deployment - Single Service

In this example, we release a new version of an Application which has single service using the blue/green deployment strategy.

Steps to follow

1. version 1 is serving traffic

2. deploy version 2

3. wait until version 2 is ready

4. switch incoming traffic from version 1 to version 2

5. shutdown version 1

In practice

Step 1: Deploy the first application

kubectl apply -f app-v1.yaml

Test if the deployment was successful. Browse using the NodeIP and NodePort

To see the deployment in action, open a new terminal and run the following

 kubectl get pods --watch

Then deploy version 2 of the application

kubectl apply -f app-v2.yaml

Wait for all the version 2 pods to be running

kubectl rollout status deploy my-app-v2 -w

Side by side, 3 pods are running with version 2 but the service still send traffic to the first deployment.

If necessary, you can manually test one of the pod by port-forwarding it to your local environment.

Once your are ready, you can switch the traffic to the new version by patching the service to send traffic to all pods with label version=v2.0.0

kubectl patch service my-app -p '{"spec":{"selector":{"version":"v2.0.0"}}}'

Test if the deployment was successful. Browse using the NodeIP and NodePort

In case you need to rollback to the previous version

kubectl patch service my-app -p '{"spec":{"selector":{"version":"v1.0.0"}}}'

If everything is working as expected, you can then delete the v1.0.0 deployment

kubectl delete deploy my-app-v1

Cleanup

kubectl delete all -l app=my-app