RFE - CNI provider

[christianh814]

Currently, Calico is used as the CNI provider. Although that's a sane default, the option should really be left to the end user. CLI option like...

• --cni-provider=calico
• --cni-provider=weavenet
• --cni-provider=flannel

First pass through, the version is the "latest stable". Future, make that part of the --cni-provider option? (something like --cni-provider=calico3.20)

[NillsF]

Been giving this some thought as well, and I see a couple of options:

• Either pass in CNI by name
• Pass in CNI by linking to a URL

We could even do both.

• --cni-provider= xxx for well-known CNI providers.
• --cni-provider-url= xxx for unknown CNI providers.

Given that cluster-api itself doesn't install a CNI provider, I personally think the second approach is a fair option if users need a different CNI provider.

Also, for calico, Azure needs a specific URL. It's coded that way right now in the create azure cluster code. Weave doesn't need this. Not sure how this would work for other CNI providers.