helm-charts Agent Skills & AI Rules

# Instructions for AI Agents

The following guidelines apply to all files in this repository.

## Repository Overview

This is the **Prometheus Community Helm Charts** repository — a collection of Helm charts for Prometheus ecosystem components. Charts are published to both a Helm repository (`prometheus-community`) and as OCI artifacts on `ghcr.io`.

## Charts

All charts live under `charts/` with a subfolder for each chart.  The subfolder names must match the chart name as described in the Chart.yaml file `.name`.

Each chart follows standard Helm structure (`Chart.yaml`, `values.yaml`, `templates/`). Some charts will organize components into subdirectories (e.g., `templates/grafana/`, `templates/prometheus/`, `templates/alertmanager/` in `kube-prometheus-stack`).

## Feature Implementation Workflow

Most agent tasks in this repository are chart feature changes. For these tasks:

1. Identify the affected chart under `charts/<chart>/` and keep changes scoped to that chart.
2. Read the relevant `Chart.yaml`, `values.yaml`, templates, helpers, and existing tests before editing.
3. Implement the feature using the chart's existing template style and values structure.
4. If `values.yaml` changes in a schema-enabled chart, update schema annotations and regenerate `values.schema.json`.
5. Add or update focused helm-unittest coverage for the rendered behavior controlled by the feature.
6. Bump the chart version in `Chart.yaml` according to SemVer.
7. Run the relevant validation commands, normally `helm unittest --strict --file 'unittests/**/*.yaml' charts/<chart-name>` and any required schema generation command.

Ask the user for clarification only when the intended chart, feature behavior, or compatibility impact cannot be inferred from the request and local context.

## Values Schema

Some charts generate `values.schema.json` from `values.yaml` using `helm-values-schema-json`. A chart uses this flow if `values.yaml` contains `# @schema` comments or a top-level `# $schema: ./values.schema.json` comment. Upstream documentation lives at https://github.com/losisin/helm-values-schema-json/blob/main/docs/README.md; use Context7 for current docs when available.

Helm validates chart values with JSON Schema draft-07. Keep generated schemas compatible with draft-07 even if external schema tooling supports newer drafts.

When changing `values.yaml` in a schema-enabled chart:

- Use the `helm-values-schema` skill for detailed schema annotation and regeneration rules.
- Preserve and update nearby `# @schema` annotations.
- Add `# @schema` annotations when inferred schema types would be wrong or too loose.
- Keep `# @schema` comments before helm-docs comments (`# -- ...`) when both are present.
- Regenerate `values.schema.json` with `helm schema` from the chart directory and include it in the change.
- Add or update helm-unittest coverage for rendered behavior controlled by the changed values.

## pre-commit testing

### helm-unittests

Pull Requests against this repository require that all charts which implement helm-unittests(https://github.com/helm-unittest/helm-unittest) must pass all of their unittests. CI runs them as an `additional-commands` entry of `ct lint` (see `.github/linters/ct.yaml`). The same command run from the repository root:

```bash
helm unittest --strict --file 'unittests/**/*.yaml' charts/<chart-name>
```

### per-chart lint scripts

A chart may carry a `ci/lint.sh`, which `ct lint` runs in addition to the unittests. `kube-prometheus-stack` uses it to verify that the generated CRDs, rules and dashboards are in sync, so changes there have to be produced by the scripts under `hack/` rather than edited in place.

## Contributing Conventions

- **One chart per PR**: CI enforces that PRs only change a single chart.
- **PR title format**: Must start with `[chart-name] ` (e.g., `[grafana] Add new feature`).
- **Version bumps**: Every chart change (excluding files listed in `.helmignore`) requires a SemVer version bump in `Chart.yaml`. Major bumps for breaking changes.
- **DCO sign-off**: Commits must include `Signed-off-by` line (`git commit -s`).
- **Squash merge only**: The repository only allows squash merges.
- **Generated files**: `.github/CODEOWNERS`, `MAINTAINERS.md` and `.github/advanced-issue-labeler.yml` are generated from `charts/` by `scripts/generate-codeowners.sh`, `scripts/generate-maintainers.sh` and `scripts/generate-labeler.sh`. Do not edit them directly.
- **Minimum Kubernetes version**: Charts that declare `kubeVersion` in `Chart.yaml` use a `>=` range, and the value differs per chart (`>=1.25.0-0` for `kube-prometheus-stack`, lower elsewhere). Most charts declare none at all. Match the chart you are editing instead of assuming a repository-wide floor.

## Dependency Management

Renovate manages all dependency updates.