step-4

Add kube-controller-manager

Remarks

• Configure kube-controller-manager, which runs the different controller processes.
• The ServiceAccount admission controller is now enabled.
  • Default service accounts and their tokens are created by the Service Account controller process.
  • kube-controller-manager is configured with a key to sign Service Account tokens.
• A Deployment definition is now used instead of a Pod.
  • The control plane components will create the corresponding Replica Set and Pods.
  • No need to tolerate taints anymore, since the control plane is complete.

Run it!

1. Start the VM and wait for the configuration. Then SSH into it.

   vagrant up
   vagrant ssh
   

2. Check that etcd, kube-apiserver, kube-scheduler and kube-controller-manager are running as Docker containers.

   docker ps
   

3. Check that there is a default service account and that it has one secret (its token).
   • This means that kube-controller-manager detected that there was no default service account and created it.
   • Actually, the serviceaccount controller created the service account and the serviceaccount-token controller created the token/secret.

   kubectl get sa
   

4. Create the test Deployment using kubectl and check that the 2 Pods are running. It may take a while for containers to be created due to image downloads.
   • This means that kube-controller-manager picked up the new Deployment and created the Replica Set and the Pods (this is actually done by the deployment, replicaset and replication controllers).
   • Then kube-scheduler picked up the pods and assigned a node to them.

   kubectl apply -f deployment.yaml
   kubectl get deployments
   kubectl get replicasets
   kubectl get pods
   docker ps
   

5. Change the number of replicas to 1 in the Deployment and update it.

   sed 's/^  replicas:.*/  replicas: 1/' deployment.yaml > deployment-1-replica.yaml
   kubectl apply -f deployment-1-replica.yaml
   kubectl get deployments
   kubectl get pods
   

6. Close the SSH connection and destroy the VM

   logout
   vagrant destroy -f