Use protobuf encoding for core K8s APIs in apiserver-network-proxy

[tosi3k]

For core K8s API objects like Pods, Nodes, etc., we can use protobuf encoding which, compared to the default JSON encoding, reduces CPU consumption related to (de)serialization, reduces overall latency of the API calls, reduces memory footprint and the work performed by the GC and results in quicker propagation of objects to event handlers of shared informers.

Core system components of K8s default their serialization method to protobuf for 8 years already: kubernetes/kubernetes#25738.

Some benchmarks comparing JSON vs. protobuf showcasing how the latter data format (de)serializes faster and uses less memory:

• https://medium.com/@akresling/go-benchmark-json-v-protobuf-4ec3c62ec8d4
• https://www.codingexplorations.com/blog/performance-comparison-protobuf-marshaling-vs-json-marshaling-in-go
• https://medium.com/@david_turner/protocol-buffers-just-how-fast-are-they-9ec19ea580db

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @tosi3k. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[tosi3k]

/assign @cheftako

[jkh52]

/ok-to-test

[jkh52]

The only failure is with lint, and this PR is not likely the culprit:

level=info msg="[runner] linters took 15.706254297s with stages: goanalysis_metalinter: 15.075948509s"
cmd/agent/app/server.go:104:2: undefined: klog (typecheck)
	klog.V(1).Infoln("Shutting down agent.")
	^
cmd/agent/app/server.go:126:2: undefined: klog (typecheck)
	klog.V(2).InfoS("Received first signal", "signal", s)
	^
cmd/agent/app/server.go:129:2: undefined: klog (typecheck)
	klog.V(2).InfoS("Received second signal", "signal", s)
	^
pkg/server/backend_manager.go:64:1: missing return (typecheck)
}
^

[cheftako]

I like the change.
I have concern that there might be edge cases where this might cause problems.
I do not know of any but wonder for instance if we have adequately tested this with the system running in HTTP-CONNECT mode rather than GRPC.
I think it would be good to at least have a flag to allow someone to revert to the legacy behavior if they do suspect a problem.

[jkh52]

I like the change. I have concern that there might be edge cases where this might cause problems. I do not know of any but wonder for instance if we have adequately tested this with the system running in HTTP-CONNECT mode rather than GRPC. I think it would be good to at least have a flag to allow someone to revert to the legacy behavior if they do suspect a problem.

+1 to a flag, but the default should be protobuf (I don't see much risk here).

[tosi3k]

Thanks - added appropriate flag to both the agent and the server with defaulting to protobuf.

PTAL :)

[k8s-ci-robot]

@tosi3k: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-apiserver-network-proxy-make-lint-master	e68f77b	link	true	/test pull-apiserver-network-proxy-make-lint-master

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[jkh52]

/lgtm
/approve

(The lint error should hopefully be resolved soon, and this PR will become merge-able.)

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jkh52, tosi3k

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[tosi3k]

@jkh52 given it's an unrelated linter failure, maybe we can force submit the PR? :)

Although I suppose it could wait for Monday given Friday is the worst day for releasing / submitting anything, especially in controversial ways like force submitting.

[tosi3k]

@cheftako @jkh52 friendly ping :)