CFP: CNI GC, STATUS support

[squeed]

CNI v1.1, which just released, includes two new verbs. It would be nice if CRI-O included support for them.

The verb STATUS allows for a plugin to indicate readiness to accept ADD requests. This takes the place of the awkward "let me remove my network configuration file because I'm upgrading" dance. It's all much cleaner. cri-o should "delegate" the Status CRI request to the CNI plugin(s).

The verb GC is a way for the runtime to pass a list of known-valid sandboxes to the CNI plugin. The CNI plugin can then clean up stale resources, such as leaked IPAM records. This will have to be invoked by cri-o based on some timer, as it is not directly related to a CRI API call.

I'm happy to start work on this, especially for STATUS. I'm not familiar enough with the cri-o code to immediately attack GC, but I'm happy to help provide guidance.

[squeed]

cri-o/ocicni#196 adds STATUS support to ocicni.

I'll see about GC support.

[squeed]

I should have a PR for ocicni GC support shortly. I'll need a bit of help folding it in to cri-o.

[squeed]

@jcaamano has agreed to take a look at this :-)

[squeed]

An update: STATUS will require no work besides bumping ocicni. GC will be a lot trickier :-)

[saschagrunert]

OCI CNI v0.4.3 should have the feature available now: https://github.com/cri-o/ocicni/releases/tag/v0.4.3