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piyush1711 / kubernetes-k8s-version-upgradation

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Kubernates upgrade from 18.x to 19.x on CentOs-7

In order to upgrade to immediate next version, taking the backup of etcd.

sudo cp -r /etc/kubernetes/ backup/

Taking a Snapshot of etcd

docker run --rm -v $(pwd)/backup:/backup \
  --network host \
  -v /etc/kubernetes/pki/etcd:/etc/kubernetes/pki/etcd \
  --env ETCDCTL_API=3 \
  k8s.gcr.io/etcd:3.4.3-0 \
  etcdctl --endpoints=https://127.0.0.1:2379 \
  --cacert=/etc/kubernetes/pki/etcd/ca.crt \
  --cert=/etc/kubernetes/pki/etcd/healthcheck-client.crt \
  --key=/etc/kubernetes/pki/etcd/healthcheck-client.key \
  snapshot save /backup/etcd-snapshot-latest.db

The below command is optional and only relevant if you use a configuration file for kubeadm. Storing this file makes it easy to initialize the master with the exact same configuration as before when restoring it.

Backup kubeadm-config

sudo cp /etc/kubeadm/kubeadm-config.yaml backup/
Before you begin the upgrade
1.Make sure you read the release notes carefully. 2.The cluster should use a static control plane and etcd pods or external etcd. 3.Make sure to back up any important components, such as app-level state stored in a database. kubeadm upgrade does not touch your workloads, only components internal to Kubernetes, but backups are always a best practice. 4.Swap must be disabled.

On Master:

Determine which version to upgrade to find the version in the list it should look like 1.19.x-0, where x is the latest patch 
yum list --showduplicates kubeadm --disableexcludes=kubernetes
#find the version in the list
#it should look like 1.19.x-0, where x is the latest patch

Call "kubeadm upgrade"

For the first control plane node

Upgrade kubeadm:

# replace x in 1.19.x-0 with the latest patch version
 yum install -y kubeadm-1.19.x-0 --disableexcludes=kubernetes

Verify the upgrade plan:

kubeadm upgrade plan

For applying the installed version

# replace x with the patch version you picked for this upgrade
sudo kubeadm upgrade apply v1.19.x

Drain the node :

# replace <node-to-drain> with the name of your node you are draining
  kubectl drain <node-to-drain> --ignore-daemonsets

Upgrade kubelet and kubectl

 # replace x in 1.19.x-0 with the latest patch version
   yum install -y kubelet-1.19.x-0 kubectl-1.19.x-0 --disableexcludes=kubernetes

Restarting Kubelet:

 sudo systemctl daemon-reload
 sudo systemctl restart kubelet

Uncordon the node

Bring the node back online by marking it schedulable:

# replace <node-to-drain> with the name of your node
kubectl uncordon <node-to-drain>

On Worker Nodes:

``` # replace x in 1.19.x-0 with the latest patch version yum install -y kubeadm-1.19.x-0 --disableexcludes=kubernetes ``` After installation Kubeadm need to be upgraded: ``` sudo kubeadm upgrade node ``` Drain the node: ``` # replace with the name of your node you are draining kubectl drain --ignore-daemonsets ```

Now Upgrade Kubectl and kubelet:

 # replace x in 1.19.x-0 with the latest patch version
 yum install -y kubelet-1.19.x-0 kubectl-1.19.x-0 --disableexcludes=kubernetes

Reload and Restart

 sudo systemctl daemon-reload
 sudo systemctl restart kubelet

Uncordon the node: Bring the node back online by marking it schedulable.

  # replace <node-to-drain> with the name of your node
    kubectl uncordon <node-to-drain>

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