Upgrade

Flannel upgrade/downgrade procedure

There are different ways of changing flannel version in the running cluster:

Remove old resources definitions and install a new one.

Pros: Cleanest way of managing resources of the flannel deployment and no manual validation required as long as no additional resources was created by administrators/operators
Cons: Massive networking outage within a cluster during the version change

1. Delete all the flannel resources using kubectl

bash

kubectl -n kube-flannel delete daemonset kube-flannel-ds
kubectl -n kube-flannel delete configmap kube-flannel-cfg
kubectl -n kube-flannel delete serviceaccount flannel
kubectl delete clusterrolebinding.rbac.authorization.k8s.io flannel
kubectl delete clusterrole.rbac.authorization.k8s.io flannel
kubectl delete namespace kube-flannel

2. Install the newer version of flannel and reboot the nodes

On the fly version

Pros: Less disruptive way of changing flannel version, easier to do
Cons: Some version may have changes which can't be just replaced and may need resources cleanup and/or rename, manual resources comparison required

If the update is done from newer version as 0.20.2 it can be done using kubectl

bash

kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml

In case of error on the labeling follow the previous way.

Using the helm repository

From version 0.21.4 flannel is deployed on an helm repository at https://flannel-io.github.io/flannel/ it will be possible to manage the update directly with helm.

bash

helm upgrade flannel --set podCidr="10.244.0.0/16" --namespace kube-flannel flannel/flannel