Prometheus Alert Rule Companion (VS Code)

Lints Prometheus alert rule YAML — duplicate alert names, missing for:, missing summary/description annotations, empty expr:. No data leaves your editor.

v0.1, new niche. Not a port from the Gap Hunter Labs IntelliJ- family catalog. Evidence: pint (Cloudflare) documents 37 real checks for Prometheus alert rules and is CLI-only — no editor integration mentioned anywhere in its own docs. The one VS Code extension with real PromQL language-server intelligence "isn't published on the Extensions Marketplace yet" — the published alternatives are syntax-highlighting only.

What it checks

Live, on any .yml/.yaml file that contains Prometheus-shaped alert rules (groups: → rules: → - alert:):

• Duplicate alert names — the same alert: name declared twice.
• Missing for: — an alert with no sustained-duration guard can fire on a single scrape blip instead of a real condition (for: 0s/0m is treated the same as missing — fires instantly).
• Missing annotations — no summary or description under annotations: — whoever gets paged has no context.
• Empty expr: — a rule with no expression can never fire.

v0.1 scope, honestly noted: a text-only structural subset of pint's 37 checks — not full PromQL parsing. pint's semantic checks (promql/impossible, promql/fragile, and the rest of its promql/* family) need a real PromQL grammar and aren't attempted here. Parsing is a hand-rolled, indentation-aware line scanner for the known Prometheus rule-group shape, not a general YAML parser.

Privacy

See PRIVACY.md — zero network calls, everything runs against files already open in your editor.

Development

npm install
npm run compile   # or: npm run watch
npm test

To build an installable package without publishing:

npx @vscode/vsce package

License

Apache License 2.0 — see LICENSE.