Support for Prometheus exporter in HAProxy

[kgodara912]

Enabled compilation flag USE_PROMEX to support prometheus exporter in HAProxy.

Merge Checklist

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

• The toolchain has been rebuilt successfully (or no changes were made to it)
• The toolchain/worker package manifests are up-to-date
• Any updated packages successfully build (or no packages were changed)
• Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
• Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
• All package sources are available
• cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
• LICENSE-MAP files are up-to-date (./LICENSES-AND-NOTICES/SPECS/data/licenses.json, ./LICENSES-AND-NOTICES/SPECS/LICENSES-MAP.md, ./LICENSES-AND-NOTICES/SPECS/LICENSE-EXCEPTIONS.PHOTON)
• All source files have up-to-date hashes in the *.signatures.json files
• sudo make go-tidy-all and sudo make go-test-coverage pass
• Documentation has been updated to match any changes to the build system
• Ready to merge

---

Summary

What does the PR accomplish, why was it needed?

• This PR adds support for Prometheus exporter in HAProxy module as per the customer requirement.

Change Log

• Change
• Change
• Change

Does this affect the toolchain?

NO

Associated issues

• Fixes WorkItem: 55931268

Links to CVEs

Test Methodology

• Pipeline build id: 718262
• Checked that installed package has flag USE_PROMEX=1 enabled by running haproxy -vv

$ haproxy -vv
HAProxy version 2.9.11-3c54f78 2024/09/19 - https://haproxy.org/
...
  OPTIONS = USE_GETADDRINFO=1 USE_OPENSSL=1 USE_ZLIB=1 USE_SYSTEMD=1 USE_PROMEX=1 USE_PCRE2=1
Feature list : ... +PROMEX

...
Built with the Prometheus exporter as a service
...
Available services : prometheus-exporter
...

[mfrw]

Fixes: #12011

[mfrw]

LGTM :)

[jslobodzian]

@kgodara912 why did we drive this through fast-track? Please target feature change PRs to 3.0-dev.

[kgodara912]

Thanks @jslobodzian for the review, from the workitem comment, I felt that it is required for February release, which is within a week, so raised review for fast-track. I will check with Eric once if it is fine to go with 3.0-dev.

[kgodara912]

Hi @jslobodzian, as per Eric, it is not that rare exception to be qualified for fast-track branch. I have raised another PR 12095 on 3.0-dev branch. Thanks for your suggestion.