Kubernetes Course Labs

Lab Solution

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

Deploy the v1 Service

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

Switch to v2

• 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.

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