Usage

check

Validate one or more config files:

amlint check alertmanager.yml
amlint check prod.yml staging.yml    # multiple files
cat alertmanager.yml | amlint check -  # stdin

Options:

flag	description
--strict	Exit non-zero on WARN as well as ERROR
--format json	Machine-readable JSON output
--format sarif	GitHub Code Scanning SARIF output
--ignore CODE	Skip findings with these codes; repeat or comma-separate
--only CODE	Show only findings with these codes; repeat or comma-separate
--exit-zero	Always exit 0 regardless of findings; useful for informational CI runs

Project config — amlint loads config automatically. Two options (first found wins):

.amlint.ymlpyproject.toml

ignore:
  - empty-receiver
  - unused-receiver
strict: true
severity:
  empty-receiver: info      # downgrade warn → info
  unused-receiver: error    # upgrade info → error

[tool.amlint]
ignore = ["empty-receiver", "unused-receiver"]
strict = true

[tool.amlint.severity]
empty-receiver = "info"
unused-receiver = "error"

.amlint.yml takes priority over pyproject.toml if both exist. --ignore on the CLI merges with the ignore: list from the config file.

Exit codes

code	meaning
0	No issues (or only WARN/INFO without --strict)
1	One or more ERROR found (or WARN with --strict)
2	File not found or YAML parse error

JSON output

amlint check alertmanager.yml --format json

[
  {
    "level": "error",
    "code": "undefined-receiver",
    "message": "Route references receiver 'pager' which is not defined...",
    "where": "route.routes[1]"
  }
]

diff

Show what changed between two configs. Useful in CI to catch regressions on PRs:

amlint diff main.yml feature-branch.yml

  FIXED  Route references receiver 'pager-team'...
  ↳ route.routes[1]  [undefined-receiver]

  NEW    match_re for 'service' does not compile...
  ↳ route.routes[3]  [bad-regex]

  1 fixed · 1 new · 4 unchanged

Exits 1 if any new findings appeared (regressions), 0 otherwise.

In CI (PR check)

- name: Check for regressions
  run: |
    git show origin/main:alertmanager.yml > /tmp/main.yml
    amlint diff /tmp/main.yml alertmanager.yml

init

Generate a minimal valid alertmanager.yml to start from:

amlint init > alertmanager.yml

list

Print all check codes with their level and a one-line description:

amlint list

explain

Show a detailed description, why it matters, and bad/good examples for any check code:

amlint explain undefined-receiver
amlint explain inhibit-no-equal

Useful for onboarding new team members or understanding an unfamiliar finding.

--version

amlint --version

SARIF (GitHub Code Scanning)

SARIF output lets GitHub show findings as annotations directly on the PR diff — no plugins required:

- name: Run amlint
  run: amlint check alertmanager.yml --format sarif > results.sarif

- name: Upload to GitHub Code Scanning
  uses: github/codeql-action/upload-sarif@v3
  with:
    sarif_file: results.sarif

CI integration

# .github/workflows/alertmanager.yml
name: Lint Alertmanager config

on: [push, pull_request]

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v7
      - run: pip install amlint
      - run: amlint check alertmanager.yml --strict