Migrating Your Existing Applications to a New Node Worker Group in Amazon EKS

Supposing you've an existing node group in your cluster and you want to migrate your applications to it. ```bash eksctl get nodegroups --cluster=demo ``` ```bash CLUSTER NODEGROUP CREATED MIN SIZE MAX SIZE DESIRED CAPACITY INSTANCE TYPE IMAGE ID demo ng-a1234567 2020-03-11T13:46:19Z 1 1 1 t3.small ``` Create a new node group using ``eksctl`` ```bash eksctl create nodegroup \ --cluster demo \ --version auto \ --name ng-b1234567 \ --node-type t3.medium \ --nodes 1 \ --region=ap-southeast-1 \ --alb-ingress-access \ --full-ecr-access \ --node-ami auto ``` If you see the following message ``` [ℹ] nodegroup "ng-b1234567" has 0 node(s) [ℹ] waiting for at least 1 node(s) to become ready in "ng-b1234567" ``` then label the node ``` kubectl label nodes -l alpha.eksctl.io/cluster-name=demo alpha.eksctl.io/nodegroup-name=ng-b1234567 --overwrite ``` Once you execute the above command, you should see ```bash [ℹ] nodegroup "ng-b1234567" has 1 node(s) [ℹ] node "ip-192-168-1-11.ap-southeast-1.compute.internal" is ready [✔] created 1 nodegroup(s) in cluster "demo" [✔] created 0 managed nodegroup(s) in cluster "demo" [ℹ] checking security group configuration for all nodegroups [ℹ] all nodegroups have up-to-date configuration ``` Get the node groups again ```bash eksctl get nodegroups --cluster=demo ``` A new node group is created ```bash CLUSTER NODEGROUP CREATED MIN SIZE MAX SIZE DESIRED CAPACITY INSTANCE TYPE IMAGE ID demo ng-b1234567 2020-03-13T13:42:26Z 1 1 1 t3.medium ami-08805da128ddc2ee1 demo ng-a1234567 2020-03-11T13:46:19Z 1 1 1 t3.small ``` Check if your worker nodes are in ``READY`` state or not by running ```bash kubectl get nodes ``` Delete the original node group. > This will drain all pods from that nodegroup before the instances are deleted. ```bash eksctl delete nodegroup --cluster demo --name ng-a1234567 ``` If you run ```bash kubectl get pod ``` You see the old pods are terminating and the new ones are creating ```bash NAME READY STATUS RESTARTS AGE app1-789d756b58-k8qvm 0/1 Terminating 0 46h app1-789d756b58-pnbjz 0/1 Pending 0 35s app2-f9b4b849c-2j2gd 0/1 Pending 0 35s app2-f9b4b849c-znwqs 0/1 Terminating 0 26h ``` After a while, you should see both pods back to Running state. Reference: [EKS Managed Nodegroups](https://eksctl.io/usage/eks-managed-nodegroups/)