Removing microk8s snap doesn't kill calico-node

[MrMYHuang]

microk8s version: microk8s (1.22/stable) v1.22.4

Steps to reproduce the bug:

sudo snap install microk8s --classic
microk8s kubectl get pod -A --watch

Then, wait until calico-node is ready.

Then, run sudo snap remove microk8s. You will find calico-node still run by ps aux|grep calico-node.

myh@alston-ubuntu:~$ ps aux|grep calico-node
root     1212222  5.1  0.1 1953788 58432 ?       Sl   14:07   0:14 calico-node -felix

It continues generating iptables-legacy rules (even if do flush rules and delete chains) and breaks cilium L7 policy functions (see cilium/cilium#18350 (comment)).

A workaround is killing calico-node manually.

[stale]

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[sbe-arg]

This issue is very annoying...