Add cluster_name label requirement to AlertManager integration docs

[Avi-Robusta]

Summary

Updated the AlertManager integration documentation to include a prerequisite step about verifying cluster identification labels before configuring third-party AlertManagers.

Key Changes

• Added a new first step requiring verification that all alerts contain either a cluster_name or cluster label matching the cluster_name defined in Robusta's configuration
• Renumbered all subsequent steps (2-5 become 3-6) to accommodate the new prerequisite
• Clarified that this label is necessary for proper alert routing to the correct robusta-runner instance

Details

This documentation change emphasizes an important configuration requirement that was previously missing from the setup instructions. The cluster identification label is critical for the system to correctly route alerts from third-party AlertManagers to the appropriate robusta-runner, preventing alerts from being sent to the wrong cluster.

https://claude.ai/code/session_01XbDk2RmpFufF1fr1EpD1EH

[github-actions]

✅ Docker image ready for bb65ca6 (built in 3m 28s)

• us-central1-docker.pkg.dev/robusta-development/temporary-builds/robusta-runner:bb65ca6

⚠️ Warning: does not support ARM (ARM images are built on release only - not on every PR)

Use this tag to pull the image for testing.

📋 Copy commands

⚠️ Temporary images are deleted after 30 days. Copy to a permanent registry before using them:

gcloud auth configure-docker us-central1-docker.pkg.dev
docker pull us-central1-docker.pkg.dev/robusta-development/temporary-builds/robusta-runner:bb65ca6
docker tag us-central1-docker.pkg.dev/robusta-development/temporary-builds/robusta-runner:bb65ca6 me-west1-docker.pkg.dev/robusta-development/development/robusta-runner-dev:bb65ca6
docker push me-west1-docker.pkg.dev/robusta-development/development/robusta-runner-dev:bb65ca6

Patch Helm values in one line:

helm upgrade --install robusta robusta/robusta \
  --reuse-values \
  --set runner.image=me-west1-docker.pkg.dev/robusta-development/development/robusta-runner-dev:bb65ca6

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

---

Walkthrough

Documentation update to AlertManager integration workflow that adds a preliminary validation step for cluster labels and reorders subsequent API key configuration steps. Updates example credentials to use ACCOUNT_ID and API_KEY format.

Changes

Cohort / File(s)	Summary
AlertManager Integration Documentation docs/configuration/alertmanager-integration/outofcluster-prometheus.rst	Adds preliminary validation step to verify alerts include cluster_name or cluster label, reorders workflow steps accordingly, and updates credentials example to use ACCOUNT_ID and API_KEY instead of signing key.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related PRs

• Docs for sending grafana alerts to the timeline #1871: Updates AlertManager/Grafana integration docs to require cluster label verification and use account_id/API key credentials.
• [ROB-3078] update alertmanager docs #2011: Modifies the same AlertManager docs to adjust "Send Alerts to Robusta with API Key" credentials format to ACCOUNT_ID/API_KEY.
• Remove CLOUD_ROUTING #1862: Modifies the same AlertManager docs and reorders steps to make cluster_name/cluster label verification the first step.

Suggested reviewers

• arikalon1
• RoiGlinik

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and concisely describes the main change: adding a cluster_name label requirement to AlertManager integration documentation.
Description check	✅ Passed	The description provides clear details about the changes, explaining the prerequisite step, renumbering of steps, and the rationale for the cluster identification label requirement.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Merge Conflict Detection	✅ Passed	✅ No merge conflicts detected when merging into master

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch claude/add-cluster-validation-docs-NCRsa

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}