COO-1063: fix: set default resource requests and limits on Alertmanager and Thanos sidecar

[jan--f]

When a ResourceQuota is set on the namespace, Alertmanager and Prometheus pods fail to start because the Alertmanager container and Thanos sidecar container don't have resource requests/limits. Propagate the MonitoringStack's resource requirements to both components, matching what is already done for the Prometheus container.

[openshift-ci-robot]

@jan--f: This pull request references COO-1063 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the bug to target the "5.0.0" version, but no target version was set.

Details

In response to this:

When a ResourceQuota is set on the namespace, Alertmanager and Prometheus pods fail to start because the Alertmanager container and Thanos sidecar container don't have resource requests/limits. Propagate the MonitoringStack's resource requirements to both components, matching what is already done for the Prometheus container.

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[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jan--f

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Details

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• pkg/controllers/monitoring/OWNERS [jan--f]

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository YAML (base), Organization UI (inherited)

Review profile: CHILL

Plan: Enterprise

Run ID: 57416592-9aad-4d87-bbba-d32e664f06c2

📥 Commits

Reviewing files that changed from the base of the PR and between d0bde27 and 3d173b4.

📒 Files selected for processing (3)

• pkg/controllers/monitoring/monitoring-stack/alertmanager.go
• pkg/controllers/monitoring/monitoring-stack/components.go
• pkg/controllers/monitoring/monitoring-stack/components_test.go

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📝 Walkthrough

Walkthrough

This PR adds resource propagation from MonitoringStack specifications to generated monitoring components. The newAlertmanager function now sets Spec.Resources from the stack configuration, and newPrometheus configures both Spec.Resources and the Thanos sidecar's Resources field from the same source. Two test cases verify that resources propagate correctly to Alertmanager and Prometheus/Thanos components.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: setting default resource requests and limits on Alertmanager and Thanos sidecar, matching the changeset content.
Description check	✅ Passed	The description is directly related to the changeset, explaining the problem (ResourceQuota issues) and the solution (propagating resource requirements to both components).
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

Error: can't load config: unsupported version of the configuration: "" See https://golangci-lint.run/docs/product/migration-guide for migration instructions
The command is terminated due to an error: can't load config: unsupported version of the configuration: "" See https://golangci-lint.run/docs/product/migration-guide for migration instructions

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[simonpasquier]

hmm wouldn't that be too inflexible/restrictive? In general Prometheus requires higher resources than Alertmanager and Thanos sidecar. Also it would double the requests for the Prometheus pods?