Replace k8s dependency to resolve protobuf version mismatch error

[Ryan-Rose-Bose]

I've been attempting to use go-cache in conjunction with a gin service instrumented with prometheus and have been running up against the following issue described in this issue:

panic: mismatching message name: got k8s.io.kubernetes.pkg.watch.versioned.Event, want github.com/ericchiang.k8s.watch.versioned.Event

goroutine 1 [running]:
google.golang.org/protobuf/internal/impl.legacyLoadMessageDesc(0x55ba9b96e7e0, 0x55ba9b8f6140, 0x55ba9b735203, 0x2f, 0x0, 0x0)
	/vendor/google.golang.org/protobuf/internal/impl/legacy_message.go:136 +0x884
google.golang.org/protobuf/internal/impl.legacyLoadMessageInfo(0x55ba9b96e7e0, 0x55ba9b8f6140, 0x55ba9b735203, 0x2f, 0x55ba9b171219)
	/vendor/google.golang.org/protobuf/internal/impl/legacy_message.go:48 +0xbf
google.golang.org/protobuf/internal/impl.Export.LegacyMessageTypeOf(0x55ba9b963e60, 0x0, 0x55ba9b735203, 0x2f, 0xc00003c9a0, 0xc000109450)
	/vendor/google.golang.org/protobuf/internal/impl/legacy_export.go:33 +0xa7
github.com/golang/protobuf/proto.RegisterType(0x55ba9b963e60, 0x0, 0x55ba9b735203, 0x2f)
	/vendor/github.com/golang/protobuf/proto/registry.go:186 +0x4f
github.com/ericchiang/k8s/watch/versioned.init.0()
	/vendor/github.com/ericchiang/k8s/watch/versioned/generated.pb.go:76 +0x4d

This is due to the github.com/ericchiang/k8s package used in redispool.go -> inCluster() using v1.2 of github.com/golang/protobuf. After version v1.4, there's some changes that result in the above error, and v1.4 is a requirement of github.com/prometheus/client_golang. The issue on github.com/ericchiang/k8s has been open for a couple months, so I do not think it is likely it will be addressed in a timely fashion.
Comparing rest.InClusterConfig() to k8s.NewInClusterClient()/k8s.newCluster(), they both behave similarly and should be equivalent in determining cluster presence.

I've solved this by replacing the protobuf-based k8s client with a portion of the official k8s client that has near-equivalent functionality.

The downside of this is that github.com/kubernetes/client-go has more dependencies than the github.com/ericchiang/k8s client.

(Useful bookmark to hide vendor files: javascript:document.querySelectorAll("*[data-path*='vendor']").forEach(el => el.parentElement.remove()); undefined;)

[Peter-Tanski-Bose]

Looks good.

[Alex-Grant-Bose]

@Ryan-Rose-Bose I think this PR change is good. In consort I ran into this issue and overrode the single line in the generated PB. Another option would be to fork https://github.com/ericchiang/k8s and fix it ourselves. I know for Consort we wanted to keep dependencies down so sticking with the other library met our needs.

[Ryan-Rose-Bose]

Yeah, that makes sense. Is it worth keeping this change on a separate branch?

And/or, would it be possible to share the way you mitigated the PB in Consort? Is it programmatic, or are you vendoring and just edited a file?

[Ryan-Rose-Bose]

After talking with @Alex-Grant-Bose, I've made this a draft and in my own code applied the fix to github.com/ericchiang/k8s. I hope to come up with a better solution eventually :)