Skip to content

Latest commit

 

History

History
154 lines (138 loc) · 5.29 KB

multi-node-update.md

File metadata and controls

154 lines (138 loc) · 5.29 KB
Raw

Upgrading kubeadm clusters

This page explains how to upgrade a Kubernetes cluster created with kubeadm from version 1.20.x to version 1.21.x, and from version 1.21.x to 1.21.y (where y > x). Skipping MINOR versions when upgrading is unsupported.

Before you begin

  • Make sure you read the release notes carefully.
  • The cluster should use a static control plane and etcd pods or external etcd.
  • 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.
  • Swap must be disabled.

Find the latest stable 1.21 version using the OS package manager:

apt-cache madison kubeadm 
apt-cache policy kubeadm
# find the latest 1.21 version in the list
# it should look like 1.21.x-00, where x is the latest patch

For the first control plane node

  • Upgrade kubeadm
# replace x in 1.21.x-00 with the latest patch version
apt-mark unhold kubeadm && \
apt-get update && apt-get install -y kubeadm=1.21.x-00 && \
apt-mark hold kubeadm
-
# since apt-get version 1.1 you can also use the following method
apt-get update && \
apt-get install -y --allow-change-held-packages kubeadm=1.21.x-00
  • Verify that the download works and has the expected version:
kubeadm version
  • Verify the upgrade plan:
kubeadm upgrade plan
  • Choose a version to upgrade to, and run the appropriate command. For example:
# replace x with the patch version you picked for this upgrade
sudo kubeadm upgrade apply v1.21.x
  • Once the command finishes you should see:
[upgrade/successful] SUCCESS! Your cluster was upgraded to "v1.21.x". Enjoy!

[upgrade/kubelet] Now that your control plane is upgraded, please proceed with upgrading your kubelets if you haven't already done so.
  • Manually upgrade your CNI provider plugin.

Your Container Network Interface (CNI) provider may have its own upgrade instructions to follow. Check the addons page to find your CNI provider and see whether additional upgrade steps are required.

This step is not required on additional control plane nodes if the CNI provider runs as a DaemonSet.

For the other control plane nodes

Same as the first control plane node but use:

sudo kubeadm upgrade node

instead of:

sudo kubeadm upgrade apply

Also calling kubeadm upgrade plan and upgrading the CNI provider plugin is no longer needed.

Drain the node

  • Prepare the node for maintenance by marking it unschedulable and evicting the workloads:
# replace <node-to-drain> with the name of your node you are draining
kubectl drain <node-to-drain> --ignore-daemonsets

Upgrade kubelet and kubectl

  • Upgrade the kubelet and kubectl
 # replace x in 1.21.x-00 with the latest patch version
 apt-mark unhold kubelet kubectl \
 && apt-get update \
 && apt-get install -y kubelet=1.21.x-00 kubectl=1.21x-00 \
 && apt-mark hold kubelet kubectl
 -
 # since apt-get version 1.1 you can also use the following method
 apt-get update \
 && apt-get install -y --allow-change-held-packages kubelet=1.21.x-00 kubectl=1.21.x-00
  • Restart the 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>

Upgrade worker nodes

The upgrade procedure on worker nodes should be executed one node at a time or few nodes at a time, without compromising the minimum required capacity for running your workloads.

  • Upgrade kubeadm:
# replace x in 1.21.x-00 with the latest patch version
apt-mark unhold kubeadm && \
apt-get update && apt-get install -y kubeadm=1.21.x-00 && \
apt-mark hold kubeadm
-
# since apt-get version 1.1 you can also use the following method
apt-get update && \
apt-get install -y --allow-change-held-packages kubeadm=1.21.x-00

Call "kubeadm upgrade"

  • For worker nodes this upgrades the local kubelet configuration:
sudo kubeadm upgrade node
  • 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 1.21.x-00 with the latest patch version
apt-mark unhold kubelet kubectl && \
apt-get update && apt-get install -y kubelet=1.21.x-00 kubectl=1.21.x-00 && \
apt-mark hold kubelet kubectl
-
# since apt-get version 1.1 you can also use the following method
apt-get update && \
apt-get install -y --allow-change-held-packages kubelet=1.21.x-00 kubectl=1.21.x-00
  • Restart the 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>

Verify the status of the cluster

After the kubelet is upgraded on all nodes verify that all nodes are available again by running the following command from anywhere kubectl can access the cluster:

kubectl get nodes

The STATUS column should show Ready for all your nodes, and the version number should be updated.