NetworkManager, leave Calico Interfaces alone.

We've all been there. You set up your nifty new Kubernetes cluster, and choose your favorite CNI, Calico, to handle networking.

But then NetworkManager comes along and has to watch and interfere with all of these new virtual interfaces introduced by Calico.

We can tell NetworkManager to ignore these interfaces by making the new file...

/etc/NetworkManager/conf.d/calico.conf

... and including the following content inside of it.

[keyfile]
unmanaged-devices=interface-name:cali*;interface-name:tunl*;interface-name:vxlan.calico

Now those virtual interfaces used by Calico will get ignored and will not see any interference from NetworkManager. Of course, you can also always decide not to use NetworkManager, but this may not be practical in all environments.