adding zipkin open tracing

[arun0009]

This PR should resolve #46

Adding Zipkin Middleware Functions (Server, Proxy) and util functions for Tracing.

Updating go versions, workflows etc.

@jcchavezs Would appreciate it if you can review this PR.

@carlosedp - Prometheus Metrics Test is failing? I upgraded all library versions and go version to 1.16 of echo-contrib in this PR (but when I reverted back to master version of go.mod prometheus test was still failing, last test).

[codecov]

Codecov Report

Merging #48 (eff9df4) into master (978e622) will increase coverage by 4.10%.
The diff coverage is 63.11%.

❗ Current head eff9df4 differs from pull request most recent head e7bc612. Consider uploading reports for the commit e7bc612 to get more accurate results

@@            Coverage Diff             @@
##           master      #48      +/-   ##
==========================================
+ Coverage   50.00%   54.10%   +4.10%     
==========================================
  Files           5        8       +3     
  Lines         326      438     +112     
==========================================
+ Hits          163      237      +74     
- Misses        153      182      +29     
- Partials       10       19       +9     

Impacted Files	Coverage Δ
prometheus/prometheus.go	48.80% <0.00%> (+0.85%)	⬆️
zipkintracing/response_writer.go	16.00% <16.00%> (ø)
zipkintracing/tracing.go	68.75% <68.75%> (ø)
casbin/casbin.go	84.61% <100.00%> (+4.61%)	⬆️
pprof/pprof.go	100.00% <100.00%> (ø)

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[arun0009]

@carlosedp - I fixed the failing test, appreciate if you can review it?

@lammel @pafuent - Can you please review this PR?

[arun0009]

@jcchavezs - Thanks for reviewing. If you think I resolved all the open comments, can you please approve?

[jcchavezs]

Just a very minor nit. No need to call it zipkintracing, I guess you thought of this because of jaegertracing but that is actually the name of the project. How about just using zipkin?

Otherwise, truly great work!

[arun0009]

@aldas - can you please review, I think I resolved most of your comments & thanks for such a detailed explanation.

[arun0009]

Just a very minor nit. No need to call it zipkintracing, I guess you thought of this because of jaegertracing but that is actually the name of the project. How about just using zipkin?

Otherwise, truly great work!

@jcchavezs - I want to leave it as zipkintracing or else it will collide with zipkin-go's package zipkin

[aldas]

LGTM

[jcchavezs]

LGTM! Great work.

[lammel]

I only have one request. Please split up the PR into the zipkin tracing related files (with this PR) and the project related changes (like ISSUE_TEMPLATE, stale bot), ... into another PR.

So only the README.md and zipkin* files should be merged with this PR.
As aldas approved already we are basically ready to merge after splitting.

[arun0009]

@lammel - Okay, force pushed just zipkin tracing changes. I'm going to send 2 additional PRs

[lammel]

Great, thanks a lot @arun0009!

[jcchavezs]

@arun0009 do you mind adding this extension into this list? https://github.com/openzipkin/openzipkin.github.io/blob/master/_data/community_tracers_instrumentation.yml. Later this will show up in https://zipkin.io/pages/tracers_instrumentation.html

[arun0009]

done @jcchavezs