Anvil

Point GitHub-shaped tools at your Forgejo instance. No rewrites.
gh · Renovate · CI scripts → your own forge, translated at the anvil.

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Anvil is a proxy that lets GitHub-compatible tools talk to a Forgejo instance as if it were GitHub. gh repo list works. Renovate works. CI status reporting works. The tools never learn the difference.

Under the hood it's Shotgun — an OpenAPI-to-OpenAPI translation proxy — wearing a curated GitHub↔Forgejo configuration: a hand-checked mappings.toml, tested live against Codeberg. The value is the mapping file, the one-command experience, and the testing.

Quickstart

git clone https://github.com/ThatXliner/shotgun shotgun
git clone https://github.com/ThatXliner/anvil anvil && cd anvil
./anvil.sh --forgejo-url https://your-forgejo.example.com

First run builds Shotgun from ../shotgun (needs a Rust toolchain). After that it starts instantly.

If you have shotgun on PATH or elsewhere, set $SHOTGUN_DIR — see anvil.sh --help.

# Test it
GH_HOST=127.0.0.1:3000 GH_TOKEN=<forgejo-token> gh api user

Note: gh requires HTTPS. Anvil speaks plain HTTP — put a reverse proxy (Caddy, nginx, Cloudflare Tunnel) in front for gh use. scripts/dev-tls-proxy.py provides a self-signed cert for local testing. Tools that don't hardcode HTTPS (curl, CI scripts, Renovate) work directly.

Coverage

86% of endpoints (75/87) are mapped, verified live against Codeberg.

Working: users (including profile edits via PATCH /user), repos, branches, issues, PRs (including merge — GitHub's PUT becomes Forgejo's POST), commit statuses, contents, the repo readme (Forgejo has no readme endpoint — Anvil serves it from the contents API; it matches a readme literally named README.md), labels, milestones, releases, webhooks, collaborators, git refs (read), pagination (per_page → limit, Link headers rewritten), Actions (runs/artifacts/secrets), search (keyword only).

Not supported: git ref create/update (Forgejo's API only reads refs), Actions variable creation (Forgejo puts the name in the path), reading a single secret back, Dependabot, Codespaces, GitHub Apps, GraphQL, Packages, code scanning. These return 501 — the same answer GitHub would give, so your tooling fails fast and loudly instead of silently misbehaving.

Extending

1. Add the endpoint path to specs/trim_github.py and/or specs/trim_forgejo.py.
2. Regenerate specs and sync mappings:

   python3 specs/trim_github.py
   python3 specs/trim_forgejo.py
   shotgun sync --source specs/github-rest-api.json --target specs/forgejo-api.json --mappings mappings.toml
   python3 specs/edit_mappings.py
   

3. Check shotgun validate --mappings mappings.toml for unresolved fields — add renames in mappings.toml or specs/edit_mappings.py.
4. Test against a real instance with curl, or add a case to the live endpoint test suite (scripts/test-p1.sh).

Project structure

mappings.toml            — the mapping configuration (start here)
anvil.sh                 — entrypoint script
specs/                   — trimmed and full OpenAPI specs, plus trim/edit scripts
scripts/test-p1.sh       — live endpoint tests
scripts/dev-tls-proxy.py — local HTTPS proxy for gh testing
Dockerfile               — containerized alternative (build from parent dir containing both anvil/ and shotgun/)

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