add: K3D_FIX_MOUNTS fix to make / rshared (e.g. to make Cilium work)

[iwilltry42]

What

New env var K3D_FIX_MOUNTS, set it to e.g. K3D_FIX_MOUNTS=1 to make / in the node containers rshared mounts.
This fixes e.g. the setup of Cilium.

If there are no bad implications of this and no one raises issues while using it throughout a few versions, we can add it as a default entrypoint.

Why

#1063

Implications

[MrPeacockNLB]

Wow waiting so long for this to get cilium working out of the box working

[deyanp]

@iwilltry42 , how can I set this env var upon creation of the cluster?

or is this not necessary, since #2246 was implemented?

Sorry, new to k3d ... and a bit confused

[iwilltry42]

@deyanp just export it in your shell before running k3d 👍
E.g.export K3D_FIX_MOUNTS=1.
It will be enabled by default in the next release.

[deyanp]

Wow, thanks @iwilltry42 !

I was thinking I should do

k3d cluster create $clusterName --registry-use $registryName:$registryPort --k3s-arg "--disable=traefik@server:*" --env 'K3D_FIX_MOUNTS=1@server:*'