handling changes to the agent's gRPC protocol buffer protocol version about kata-containers

[jodh-intel]

/cc @sboeuf, @bergwolf.

[sboeuf]

@jodh-intel Thanks for taking the time to explain this very accurately. I think that we should do two things to avoid those kind of issues as much as possible.

• Add to the developer documentation the good practices to update a .proto file
• Write a binary checking for bad practices, that would be run by the CI as part of the make check

[bergwolf]

Agreed @sboeuf. And I think we should only declare a stable API when releasing kata containers and try not to commit to any inter-operability during early stage of development for the sake of easier maintenance. IOW, while it is a nice thing to have, I would prefer to enforce it only when we are about to release kata containers.

[jodh-intel]

Yes, at this stage, I think we still expect changes to the .proto files but once we are providing packaged components, we need to be extra careful.

I've raised kata-containers/agent#175 which should give us another level of protection.