improve kong status check endpoint

[discostur]

What this PR does / why we need it:

This PR implements support for using Kong Gateway's dedicated status port (8100) for health checks instead of the Admin API port (8444). This separation of concerns improves:

• reduces "spam" to access_log
• Reducing load on the Admin API port, which is used for configuration management
• Following best practices by using dedicated endpoints for health monitoring

The implementation adds a new --kong-status-svc-port-names configuration flag (default: ["status"]) to discover Kong Gateway status endpoints, while maintaining full backward compatibility with existing Admin API-based health checks.

Which issue this PR fixes:

Users are complaining for years that the access log get spammed with status health checks:

• KONG_STATUS_ACCESS_LOG value does not work kong#13344
• Being able to optionally disable logging of "GET /status" in the access logs kong#7276

Special notes for your reviewer:

• Backward Compatibility: The implementation is fully backward compatible. If no status client is available, health checks will continue to use the Admin API as before.
• Configuration: A new configuration option --kong-status-svc-port-names has been added with sensible defaults.
• Testing: Comprehensive test coverage has been added for all new components, including unit tests, integration tests, and mock-based error scenario testing.
• Service Discovery: The existing service discovery mechanism has been extended to support both Admin API ports (admin-tls, kong-admin-tls) and status ports (status) simultaneously.

PR Readiness Checklist:

• the CHANGELOG.md release notes have been updated to reflect any significant (and particularly user-facing) changes introduced by this PR

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

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[codecov]

Codecov Report

Attention: Patch coverage is 73.18182% with 59 lines in your changes missing coverage. Please review.

Project coverage is 58.5%. Comparing base (78ebb72) to head (ed36ec1).

Files with missing lines	Patch %	Lines
internal/adminapi/client.go	29.2%	28 Missing and 1 partial ⚠️
internal/adminapi/status_client.go	76.7%	9 Missing and 4 partials ⚠️
internal/clients/status_readiness.go	91.2%	9 Missing and 1 partial ⚠️
internal/manager/run.go	0.0%	7 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (78ebb72) and HEAD (ed36ec1). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (78ebb72)	HEAD (ed36ec1)
	2	1

Additional details and impacted files

@@           Coverage Diff            @@
##            main   #7460      +/-   ##
========================================
- Coverage   77.4%   58.5%   -18.9%     
========================================
  Files        220     222       +2     
  Lines      25368   25587     +219     
========================================
- Hits       19644   14980    -4664     
- Misses      4729    9916    +5187     
+ Partials     995     691     -304     

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[discostur]

Is somebody going to look at this? Or is anything missing?

[pmalek]

Is somebody going to look at this? Or is anything missing?

Hey @discostur 👋. Thanks for the contribution.

The team will review this and will let you know if there's anything missing or that needs changing.

[programmer04]

Thank @discostur for very thoughtful and useful PR! There is one suggestion.

Since the official client library is go-kong the logic can be moved here to benefit all users as follows.

Constructor NewClient(baseURL *string, client *http.Client) (*Client, error) can be extended in a non-breaking manner to accept functional options pattern
and introduce a new parameter to optionally set a different port for a status check.

Next in the method func (c *Client) Status(ctx context.Context) (*Status, error) based on whether the port is set or not, construct a request to a proper status address and execute the check.

After the proposed change, go-kong library has logic for status check built in. We'll avoid creating a dedicated client with request logic in the KIC repo. Instead, it can be properly handled for everybody and just used in KIC with a little additional logic.

WDYT? Are you willing to take care of it? I promise quick reviews and help in case of need

[programmer04]

It's redundant

[discostur]

@programmer04 thanks for your suggestions but unfortunately i don't have the time at the moment ... :/