feat: Feature/opentel

[bearrito]

Description

Adds in support for Open Telemetry as an exporter

• The exporter exports to opentel collectors. The exporter can natively handle any of the supported opentel exporters. However, configuration of these exporters isn't supported yet. If users wanted them I think it's feasible, it just makes configuration via relay difficult.
• The reflection code to convert interfaces to opentel attributes is sketchy but tested. If there is a better approach I can do that.
• Opentel really wants you to store providers as global, I think what I have is resource safe, but it's worth noting how the provider works.
• I'd like to add more serious testing with the testcontainer

Changes include

• [+] New feature (non-breaking change that adds functionality)

Closes issue(s)

#1375

Checklist

• [+] I have tested this code
• [+] I have added unit test to cover this code
• I have updated the documentation (README.md and /website/docs)
• I have followed the contributing guide

[netlify]

❌ Deploy Preview for go-feature-flag-doc-preview failed.

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[bearrito]

@thomaspoignant Can you let me know what you think of this?

Since the Value on FeatureEvent is an interface it was a bit tricky to get in as a set of attributes. I had to make some design decisions on how to do that.

[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 42 lines in your changes are missing coverage. Please review.

Project coverage is 86.21%. Comparing base (32e4fc0) to head (db5fbdc).

Files	Patch %	Lines
exporter/opentelemetryexporter/exporter.go	76.53%	31 Missing and 11 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1770      +/-   ##
==========================================
- Coverage   86.72%   86.21%   -0.51%     
==========================================
  Files          89       90       +1     
  Lines        3367     3548     +181     
==========================================
+ Hits         2920     3059     +139     
- Misses        345      376      +31     
- Partials      102      113      +11     

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[thomaspoignant]

I am sorry to be slow on the review. I will do it very soon.

[bearrito]

I am sorry to be slow on the review. I will do it very soon.

No problem. Life exists outside github!

[sonarcloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[bearrito]

@thomaspoignant Anything else on this? I'm going on holiday and am closing out my open pr's

[thomaspoignant]

Sorry I had no time to test it properly.
But don't worry we can look at it after your vacation.