Add CORS handling for Zipkin collector service, fixes #703

[JonasVerhofste]

Signed-off-by: Jonas Verhofsté 25819942+JonasVerhofste@users.noreply.github.com

Which problem is this PR solving?

• Handling of CORS on the Zipkin collector service, issue Support CORS on Zipkin endpoint #703

Short description of the changes

• Add and call the CORS handler
• Add variables for allowed origins and headers

[JonasVerhofste]

Not entirely sure where to add tests, if any are needed at all?

[yurishkuro]

I don't think this PR needs to include Gopkg.lock changes.

Not entirely sure where to add tests, if any are needed at all?

What is the expected behavior of the cors handler? Does it reject certain types of requests? That's the type of test I would add.

[codecov]

Codecov Report

Merging #1463 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1463      +/-   ##
==========================================
+ Coverage   99.83%   99.83%   +<.01%     
==========================================
  Files         179      179              
  Lines        8550     8554       +4     
==========================================
+ Hits         8536     8540       +4     
  Misses          7        7              
  Partials        7        7

Impacted Files	Coverage Δ
cmd/collector/app/builder/builder_flags.go	100% <100%> (ø)	⬆️

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[JonasVerhofste]

I don't think this PR needs to include Gopkg.lock changes.

Removed.

What is the expected behavior of the cors handler? Does it reject certain types of requests? That's the type of test I would add.

I'm not sure where to add the tests. Where exactly does the main.go from the collector get tested?

[yurishkuro]

Ah, it's ok then. We should have a test for flags, but we don't test main aside from integration tests. Some steps in the build are failing though.

[JonasVerhofste]

@yurishkuro Well, the builds didn't fail before (https://travis-ci.org/jaegertracing/jaeger/builds/516424159) and I only removed the lock-file. Some inconsistency in the CI?

[JonasVerhofste]

@yurishkuro So, seems like build 2 (proto gen) is failing because I removed Gopkg.lock, like you asked. Should I re-add it or is that a fault in the CI?

[JonasVerhofste]

ping @yurishkuro

[yurishkuro]

Let's see if merging master helps, as this step should not be failing (it doesn't in master)

[yurishkuro]

hmm, very odd, lock file comes up as a diff. Need to look into that.

[yurishkuro]

ok, fixed it

[yurishkuro]

Ah, I see what's going on now. You're adding a new dependency github.com/rs/cors, I missed that. In that case, it needs to go to Gopkg.toml, and you DO need to update the lock file.