For blue-green updates you need two Deployment objects - each managing Pods for a different version of your app.
- solution/whoami-deployments.yaml has two Deployments defined in the same YAML, so you can easily compare them.
Kubectl supports this too, using --- to separate objects.
kubectl apply -f labs/deployments/solution/whoami-deployments.yaml
kubectl get pods -l app=whoami-lab,version=v1
kubectl get pods -l app=whoami-lab,version=v2
Four Pods are running, but there are no Services targeting their labels
The blue-green switch is done by changing the label selector for the Service.
- solution/whoami-service-v1.yaml has a LoadBalancer and NodePort Service defined - each uses the same selector to pick the v1 Pods.
Deploy and test v1:
kubectl apply -f labs/deployments/solution/whoami-service-v1.yaml
kubectl get endpoints whoami-lab-np whoami-lab-lb
curl localhost:8020 # OR curl localhost:30020
- whoami-service-v2.yaml has the same Service definitions with just a change to the selector.
Kubernetes deploys this as an update to the existing Services, so the IP addresses don't change, only the endpoints the Services find:
kubectl apply -f labs/deployments/solution/whoami-service-v2.yaml
kubectl get endpoints whoami-lab-np whoami-lab-lb
curl localhost:8020 # OR curl localhost:30020
You can flip between the deployments by changing the Service spec
Back to the exercises.