reviewdog — Turn Lint Into PR Review Comments

Practical Notes

• Quant gate: make CI fail when new issues appear (diff-only mode).
• Tip: start with -reporter=local before wiring PR credentials.

Pattern: “diff-only” quality gate

When a repo has a backlog of existing issues, the fastest rollout is only comment on new problems introduced by the PR.

1. Pick one linter and ensure it prints file/line/col.

2. Pipe to reviewdog with diff filtering:

<your_linter_cmd> | reviewdog -f=golint -reporter=github-pr-review -filter-mode=diff_context

3. Tighten gradually:

• Start as github-pr-review (developer-friendly),
• then switch to github-check (status checks) if you want a strict merge gate.

Pattern: unify many linters into one “review surface”

If your CI runs multiple tools (format, security, deps, etc.), keep the PR readable:

• Use a consistent reporter (Checks or Review),
• use consistent severity mapping,
• keep messages short and actionable (first sentence: what to change).

Troubleshooting

• If nothing posts: validate you’re running in a PR context and tokens are present.
• If comments are too noisy: use diff filtering, or limit to changed paths only.

FAQ

Q: Do I have to use GitHub Actions? A: No. reviewdog can run in many CI systems; the key is having a PR diff context when you want PR comments.

Q: Can I run it locally? A: Yes. Use -reporter=local to validate parsing and formatting before wiring CI credentials.

Q: How do I avoid commenting on old issues? A: Use diff filtering (-filter-mode=diff_context) so only new issues are surfaced.