feat: Start the relayproxy as a unix socket.

[thomaspoignant]

Description

This PR is here to support starting the relay proxy as a unix socket.

The PR contains a new format for the configuration of the relayproxy.
Moving the listen option into a server option, allowing to have a more fine grained configuration.

Closes issue(s)

Resolve #4244

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 canceled.

Name	Link
🔨 Latest commit	7f26aba
🔍 Latest deploy log	https://app.netlify.com/projects/go-feature-flag-doc-preview/deploys/690d0e4a1e66160008ac084a

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 32 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.96%. Comparing base (de4d46d) to head (7f26aba).
⚠️ Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/relayproxy/api/server.go	55.55%	14 Missing and 6 partials ⚠️
cmd/relayproxy/main.go	0.00%	7 Missing ⚠️
cmd/relayproxy/config/config_validator.go	72.22%	3 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4261      +/-   ##
==========================================
- Coverage   84.96%   84.96%   -0.01%     
==========================================
  Files         140      141       +1     
  Lines        5660     5739      +79     
==========================================
+ Hits         4809     4876      +67     
- Misses        644      651       +7     
- Partials      207      212       +5     

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[thomaspoignant]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a significant feature by adding support for running the relay proxy as a Unix socket. The configuration has been thoughtfully refactored into a more structured server block, which greatly improves clarity and future extensibility. The implementation is solid, with comprehensive updates to tests and documentation to match the new functionality. I've included a few suggestions to enhance error handling, logging consistency, and the robustness of the tests. Overall, this is an excellent and well-executed contribution.

[thomaspoignant]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces support for starting the relay proxy as a Unix socket, which is a great addition for certain deployment scenarios. The changes include a significant and well-executed refactoring of the configuration structure, moving server-related options under a new server block. Backward compatibility is thoughtfully maintained by using getter methods that handle deprecated fields and issue warnings. The documentation, examples, and Helm charts have been updated accordingly, and comprehensive tests for the new Unix socket functionality have been added. My review includes a couple of suggestions to improve test robustness and make the configuration validation logic more resilient to future changes.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[thomaspoignant]

The CI failing for the Helm Check is normal because we need to release the new version of the relay proxy to make the changes works.