fluxcd: add container-based config discovery support

[vitkyrka]

What does this PR do?

Rebased onto master now that the generic config-discovery infrastructure (the from_named_ports strategy and the datadog_checks.dev.kubernetes E2E harness) has merged via #24886, and the test infra for this integration is already on the Kubernetes Agent E2E backend.

Adds container-based config discovery support to fluxcd.

Discovery finds the FluxCD controller metrics endpoints using the named Kubernetes port http-prom.

The ad_identifiers targets somewhat generic short image names (source-controller, helm-controller, etc.) so we use a CEL selector to narrow those to FluxCD images. ad_identifiers covers all six flux-system controllers, including image-reflector-controller; the kind fixture's install.yaml deliberately excludes that controller's Deployment (it never reached Ready in CI), so it has no running pod for the E2E tests to exercise, but Autodiscovery will still match it in a real cluster.

The E2E discovery test validates that Kubernetes Autodiscovery finds all five FluxCD controller instances deployed by the kind fixture (the four covered by the non-discovery E2E test plus image-automation-controller, which the non-discovery test's fixed controller list doesn't include), and a separate test probes each of those five controllers individually to confirm generated discovery candidates don't destabilize them.

Motivation

https://datadoghq.atlassian.net/browse/DSCVR-529

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add qa/required if this PR needs QA validation, or qa/skip-qa if it does not. Exactly one of the two is required.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[datadog-prod-us1-3]

 

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 71.43%
• Overall Coverage: 87.61% (-1.03%)

_{This comment will be updated automatically if new data arrives.
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[vitkyrka]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• fluxcd: add container-based config discovery support #24510 👈 (View in Graphite)
• argo_workflows: add container-based config discovery support #24512 : 1 other dependent PR (#24511 )
• velero: add container-based config discovery support #24507 : 6 other dependent PRs (#24459 , #24506 , #24519 and 3 others)
• Add discovery port name helper #24555
• master

This stack of pull requests is managed by Graphite. Learn more about stacking.

[cit-pr-commenter-54b7da]

evalya-impact-summary

evalya impact analysis

Impact analysis: 0 selected, 0 skipped (of 0 test tasks)
Publish tasks:   1 (always emitted)
Diff (9 files):
  fluxcd/assets/configuration/spec.yaml
  fluxcd/changelog.d/24510.added
  fluxcd/datadog_checks/fluxcd/config_models/discovery.py
  fluxcd/datadog_checks/fluxcd/config_models/discovery_overrides.py
  fluxcd/datadog_checks/fluxcd/config_models/discovery_strategies.py
  fluxcd/datadog_checks/fluxcd/data/auto_conf.yaml
  fluxcd/pyproject.toml
  fluxcd/tests/conftest.py
  fluxcd/tests/test_e2e.py

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Add image-reflector-controller to autodiscovery

When Flux image automation is installed, it includes image-reflector-controller alongside image-automation-controller, and that controller exposes metrics through the same named http-prom port. Because ad_identifiers is an allow-list and omits image-reflector-controller, Autodiscovery never creates a FluxCD check for it, leaving its metrics uncollected. The E2E fixture removes this controller, so the five-controller test does not expose the omission; add the identifier to both the spec and generated auto_conf.yaml and cover it with the discovery test.

Useful? React with 👍 / 👎.

[dd-octo-sts]

Validation Report

All 21 validations passed.

Show details

Validation	Description	Status
agent-reqs	Verify check versions match the Agent requirements file	✅
ci	Validate CI configuration and code coverage settings	✅
codeowners	Validate every integration has a CODEOWNERS entry	✅
config	Validate default configuration files against spec.yaml	✅
dep	Verify dependency pins are consistent and Agent-compatible	✅
http	Validate integrations use the HTTP wrapper correctly	✅
imports	Validate check imports do not use deprecated modules	✅
integration-style	Validate check code style conventions	✅
jmx-metrics	Validate JMX metrics definition files and config	✅
labeler	Validate PR labeler config matches integration directories	✅
legacy-signature	Validate no integration uses the legacy Agent check signature	✅
license-headers	Validate Python files have proper license headers	✅
licenses	Validate third-party license attribution list	✅
metadata	Validate metadata.csv metric definitions	✅
models	Validate configuration data models match spec.yaml	✅
openmetrics	Validate OpenMetrics integrations disable the metric limit	✅
package	Validate Python package metadata and naming	✅
qa-label	Validate the pull request declares whether it needs QA for the next Agent release	✅
readmes	Validate README files have required sections	✅
saved-views	Validate saved view JSON file structure and fields	✅
version	Validate version consistency between package and changelog	✅

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