[extension/jaegerremotesampling] remove jaeger sampling dependency

[ary82]

Description

Copy the required code from jaeger to extension/jaegerremotesampling:

• Modify files to remove dependencies
• Add required code from plugin/sampling/strategyprovider/static
• Add required code from cmd/collector/app/sampling to internal

Link to tracking issue

Fixes #36976

Testing

• Add grpc_handler_test.go from cmd/collector/app/sampling/grpc_handler_test.go
• Add provider_test.go from plugin/sampling/strategyprovider/static/provider_test.go with plugin/sampling/strategyprovider/static/fixtures

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: ary82 / name: Aryan Goyal (b07a06d, e9749c9, 94c5d1f, 518347e, 7ba9b6c, 8a33757, fe2045a, 877511a, 41ca9c2, 57479e2, 8c044cf, 7818970, 27239ae, cb8d0ff, cd9aac8)

[yurishkuro]

The organization of the components needs to be improved, it's all over the place. I would recommend

internal/
  source/
    source.go - define interface
    filesource/ - define reading from file
    remotesource/ - a proxy that reads from a remote service
  server/
    grpc/ - grpc server that uses Source
    http/ - http server that uses Source and defines its own JSON model

[yurishkuro]

lgtm! Let's makes sure all CI checks are green.

[ary82]

Sorry, closing was a misclick on Close with comment
The CI showed errors on the linter. Here's what the linter says:

jaegerremotesampling/internal/source/filesource/filesource.go:378:12: Error return value of `enc.Encode` is not checked (errcheck)
	enc.Encode(*s)
	         ^
jaegerremotesampling/internal/source/filesource/filesource.go:380:12: Error return value of `dec.Decode` is not checked (errcheck)
	dec.Decode(&copyValue)
	         ^
jaegerremotesampling/internal/source/filesource/filesource_test.go:71:11: Error return value of `w.Write` is not checked (errcheck)
			w.Write([]byte("bad-content"))
			      ^
jaegerremotesampling/internal/source/filesource/filesource_test.go:85:11: Error return value of `w.Write` is not checked (errcheck)
			w.Write([]byte(*strategy.Load()))
			      ^
jaegerremotesampling/internal/source/filesource/filesource_test.go:512:17: Error return value of `os.WriteFile` is not checked (errcheck)
				os.WriteFile(snapshotFile, strategyJson, 0o644)
				           ^
jaegerremotesampling/internal/source/filesource/filesource_test.go:544:17: Error return value of `os.WriteFile` is not checked (errcheck)
				os.WriteFile(snapshotFile, strategyJson, 0o644)
				           ^
jaegerremotesampling/internal/source/filesource/filesource_test.go:371:21: G306: Expect WriteFile permissions to be 0600 or less (gosec)
	require.NoError(t, os.WriteFile(dstFile, srcBytes, 0o644))
	                  ^
jaegerremotesampling/internal/source/filesource/filesource_test.go:392:21: G306: Expect WriteFile permissions to be 0600 or less (gosec)
	require.NoError(t, os.WriteFile(dstFile, []byte(newStr), 0o644))
	                  ^
jaegerremotesampling/internal/source/filesource/filesource_test.go:469:21: G306: Expect WriteFile permissions to be 0600 or less (gosec)
	require.NoError(t, os.WriteFile(tempFile.Name(), []byte("bad value"), 0o644))

• For the file permissions in filesource_test.go, should the permissions really be 600?
• As for the errchecks in filesource in Encode and Decode, these are only used in the test and are safe to be ignored. Also should be moved to the test file(edit: fixed)

[yurishkuro]

For the file permissions in filesource_test.go, should the permissions really be 600?

600 permission should be fine

As for the errchecks in filesource in Encode and Decode, these are only used in the test and are safe to be ignored. Also should be moved to the test file(edit: fixed)

There's rarely a good reason to ignore errors, even in tests - at some point something might break, and ignored error makes it harder to debug. You can always add require.NoError(t, err) in tests.

[ary82]

Thanks for your help :) Should be fixed now

[yurishkuro]

There shouldn't be changes like this in go mod, they are not related to the pr.

[ary82]

x/net/context was being used in the grpc_handler_test file, which caused this change to go.mod.
Changed to use the stdlib context.