amlint

Semantic linter for Prometheus Alertmanager configs.

amtool check-config validates syntax. amlint validates semantics — will alerts actually reach a receiver, does the inhibition rule do anything, are there unreachable routing branches?

These are the bugs that burn teams on-call: config is valid, CI passes, alerts silently vanish.

Quick example

pip install amlint
amlint check alertmanager.yml

  ERROR  Route references receiver 'pager-team' which is not defined in receivers.
         Alerts matched here will be dropped.
  ↳ route.routes[1]  [undefined-receiver]

  WARN   Catch-all route (no matchers) with continue:false will intercept all alerts
         — 2 subsequent sibling(s) are unreachable.
  ↳ route.routes[0]  [unreachable-route]

  2 error · 3 warn · 1 info

Exit code 1 on any ERROR — ready for CI. --strict treats WARN as failure too.

Why not just amtool?

	amtool	amlint
Syntax errors	✅	✅
Undefined receiver	❌	✅
Unreachable routes	❌	✅
Bad inhibition rules	❌	✅
Invalid regex	❌	✅
Timing misconfig	❌	✅

25 checks, zero false positives

amlint catches mistakes that are syntactically valid but semantically broken. See all checks for the full list.