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Upgrading Kubernetes

This guide covers Kubernetes control plane upgrade for clusters running Talos-managed control plane. If the cluster is still running self-hosted control plane (after upgrade from Talos 0.8), please refer to 0.8 docs.

Video Walkthrough

To see a live demo of this writeup, see the video below:

Automated Kubernetes Upgrade

To upgrade from Kubernetes v1.20.1 to v1.20.4 run:

$ talosctl --nodes <master node> upgrade-k8s --from 1.20.1 --to 1.20.4
discovered master nodes ["172.20.0.2" "172.20.0.3" "172.20.0.4"]
updating "kube-apiserver" to version "1.20.4"
 > updating node "172.20.0.2"
2021/03/09 19:55:01 retrying error: config version mismatch: got "2", expected "3"
 > updating node "172.20.0.3"
2021/03/09 19:55:05 retrying error: config version mismatch: got "2", expected "3"
 > updating node "172.20.0.4"
2021/03/09 19:55:07 retrying error: config version mismatch: got "2", expected "3"
updating "kube-controller-manager" to version "1.20.4"
 > updating node "172.20.0.2"
2021/03/09 19:55:27 retrying error: config version mismatch: got "2", expected "3"
 > updating node "172.20.0.3"
2021/03/09 19:55:47 retrying error: config version mismatch: got "2", expected "3"
 > updating node "172.20.0.4"
2021/03/09 19:56:07 retrying error: config version mismatch: got "2", expected "3"
updating "kube-scheduler" to version "1.20.4"
 > updating node "172.20.0.2"
2021/03/09 19:56:27 retrying error: config version mismatch: got "2", expected "3"
 > updating node "172.20.0.3"
2021/03/09 19:56:47 retrying error: config version mismatch: got "2", expected "3"
 > updating node "172.20.0.4"
2021/03/09 19:57:08 retrying error: config version mismatch: got "2", expected "3"
updating daemonset "kube-proxy" to version "1.20.4"

Script runs in two phases:

  1. In the first phase every control plane node machine configuration is patched with new image version for each control plane component. Talos renders new static pod definition on configuration update which is picked up by the kubelet. Script waits for the change to propagate to the API server state. Messages config version mismatch indicate that script is waiting for the updated container to be registered in the API server.
  2. In the second phase script updates kube-proxy daemonset with the new image version.

If script fails for any reason, it can be safely restarted to continue upgrade process.

Manual Kubernetes Upgrade

Kubernetes can be upgraded manually as well by following the steps outlined below. They are equivalent to the steps performed by the talosctl upgrade-k8s command.

Kubeconfig

In order to edit the control plane, we will need a working kubectl config. If you don’t already have one, you can get one by running:

talosctl --nodes <master node> kubeconfig

API Server

Patch machine configuration using talosctl patch command:

$ talosctl -n <CONTROL_PLANE_IP_1> patch mc --immediate -p '[{"op": "replace", "path": "/cluster/apiServer/image", "value": "k8s.gcr.io/kube-apiserver:v1.20.4"}]'
patched mc at the node 172.20.0.2

JSON patch might need to be adjusted if current machine configuration is missing .cluster.apiServer.image key.

Also machine configuration can be edited manually with talosctl -n <IP> edit mc --immediate.

Capture new version of kube-apiserver config with:

$ talosctl -n <CONTROL_PLANE_IP_1> get kcpc kube-apiserver -o yaml
node: 172.20.0.2
metadata:
    namespace: config
    type: KubernetesControlPlaneConfigs.config.talos.dev
    id: kube-apiserver
    version: 5
    phase: running
spec:
    image: k8s.gcr.io/kube-apiserver:v1.20.4
    cloudProvider: ""
    controlPlaneEndpoint: https://172.20.0.1:6443
    etcdServers:
        - https://127.0.0.1:2379
    localPort: 6443
    serviceCIDR: 10.96.0.0/12
    extraArgs: {}
    extraVolumes: []

In this example, new version is 5. Wait for the new pod definition to propagate to the API server state (replace talos-default-master-1 with the node name):

$ kubectl get pod -n kube-system -l k8s-app=kube-apiserver --field-selector spec.nodeName=talos-default-master-1 -o jsonpath='{.items[0].metadata.annotations.talos\.dev/config\-version}'
5

Check that the pod is running:

$ kubectl get pod -n kube-system -l k8s-app=kube-apiserver --field-selector spec.nodeName=talos-default-master-1
NAME                                    READY   STATUS    RESTARTS   AGE
kube-apiserver-talos-default-master-1   1/1     Running   0          16m

Repeat this process for every control plane node, verifying that state got propagated successfully between each node update.

Controller Manager

Patch machine configuration using talosctl patch command:

$ talosctl -n <CONTROL_PLANE_IP_1> patch mc --immediate -p '[{"op": "replace", "path": "/cluster/controllerManager/image", "value": "k8s.gcr.io/kube-controller-manager:v1.20.4"}]'
patched mc at the node 172.20.0.2

JSON patch might need be adjusted if current machine configuration is missing .cluster.controllerManager.image key.

Capture new version of kube-controller-manager config with:

$ talosctl -n <CONTROL_PLANE_IP_1> get kcpc kube-controller-manager -o yaml
node: 172.20.0.2
metadata:
    namespace: config
    type: KubernetesControlPlaneConfigs.config.talos.dev
    id: kube-controller-manager
    version: 3
    phase: running
spec:
    image: k8s.gcr.io/kube-controller-manager:v1.20.4
    cloudProvider: ""
    podCIDR: 10.244.0.0/16
    serviceCIDR: 10.96.0.0/12
    extraArgs: {}
    extraVolumes: []

In this example, new version is 3. Wait for the new pod definition to propagate to the API server state (replace talos-default-master-1 with the node name):

$ kubectl get pod -n kube-system -l k8s-app=kube-controller-manager --field-selector spec.nodeName=talos-default-master-1 -o jsonpath='{.items[0].metadata.annotations.talos\.dev/config\-version}'
3

Check that the pod is running:

$ kubectl get pod -n kube-system -l k8s-app=kube-controller-manager --field-selector spec.nodeName=talos-default-master-1
NAME                                             READY   STATUS    RESTARTS   AGE
kube-controller-manager-talos-default-master-1   1/1     Running   0          35m

Repeat this process for every control plane node, verifying that state got propagated successfully between each node update.

Scheduler

Patch machine configuration using talosctl patch command:

$ talosctl -n <CONTROL_PLANE_IP_1> patch mc --immediate -p '[{"op": "replace", "path": "/cluster/scheduler/image", "value": "k8s.gcr.io/kube-scheduler:v1.20.4"}]'
patched mc at the node 172.20.0.2

JSON patch might need be adjusted if current machine configuration is missing .cluster.scheduler.image key.

Capture new version of kube-scheduler config with:

$ talosctl -n <CONTROL_PLANE_IP_1> get kcpc kube-scheduler -o yaml
node: 172.20.0.2
metadata:
    namespace: config
    type: KubernetesControlPlaneConfigs.config.talos.dev
    id: kube-scheduler
    version: 3
    phase: running
spec:
    image: k8s.gcr.io/kube-scheduler:v1.20.4
    extraArgs: {}
    extraVolumes: []

In this example, new version is 3. Wait for the new pod definition to propagate to the API server state (replace talos-default-master-1 with the node name):

$ kubectl get pod -n kube-system -l k8s-app=kube-scheduler --field-selector spec.nodeName=talos-default-master-1 -o jsonpath='{.items[0].metadata.annotations.talos\.dev/config\-version}'
3

Check that the pod is running:

$ kubectl get pod -n kube-system -l k8s-app=kube-scheduler --field-selector spec.nodeName=talos-default-master-1
NAME                                    READY   STATUS    RESTARTS   AGE
kube-scheduler-talos-default-master-1   1/1     Running   0          39m

Repeat this process for every control plane node, verifying that state got propagated successfully between each node update.

Proxy

In the proxy’s DaemonSet, change:

kind: DaemonSet
...
spec:
  ...
  template:
    ...
    spec:
      containers:
        - name: kube-proxy
          image: k8s.gcr.io/kube-proxy:v1.20.1
      tolerations:
        - ...

to:

kind: DaemonSet
...
spec:
  ...
  template:
    ...
    spec:
      containers:
        - name: kube-proxy
          image: k8s.gcr.io/kube-proxy:v1.20.4
      tolerations:
        - ...
        - key: node-role.kubernetes.io/control-plane
          operator: Exists
          effect: NoSchedule

To edit the DaemonSet, run:

kubectl edit daemonsets -n kube-system kube-proxy

Kubelet

Upgrading Kubelet version requires Talos node reboot after machine configuration change.

For every node, patch machine configuration with new kubelet version, wait for the node to reboot:

$ talosctl -n <IP> patch mc -p '[{"op": "replace", "path": "/machine/kubelet/image", "value": "ghcr.io/talos-systems/kubelet:v1.20.4"}]'
patched mc at the node 172.20.0.2

Once node boots with the new configuration, confirm upgrade with kubectl get nodes <name>:

$ kubectl get nodes talos-default-master-1
NAME                     STATUS   ROLES                  AGE    VERSION
talos-default-master-1   Ready    control-plane,master   123m   v1.20.4
Last modified March 18, 2022: docs: overhaul all the docs (e3fda049f)