feat: run on Forgejo Actions as well as GitHub Actions

natsukium commented

2026-09-19 16:15:00 +09:00

Owner

Makes the action usable from Forgejo Actions, not only GitHub Actions.
Verified end to end on this instance: run 5 posts the comment above using the
automatic workflow token, with no extra secret.

Forgejo Runner already exposes GitHub-compatible event variables, so the action
reached the right runner; what it got wrong was every URL it built.

Comment and compare links were hardcoded to github.com; they now come from
GITHUB_SERVER_URL via the action context.
The "View diff as HTML" link used GITHUB_RUN_ID. On Forgejo that is a global
database id (3516 for run 5 here, which 404s); run pages are addressed by the
repository-scoped index in GITHUB_RUN_NUMBER.
Minimizing outdated comments is skipped on Forgejo, which has no GraphQL API,
so those comments stay visible instead of failing the run.

Artifacts cannot work on Forgejo today. @actions/artifact 6.2 and later send a
mime_type field in CreateArtifact; Forgejo's CreateArtifactRequest protobuf
defines fields 1-5 only and its handler unmarshals without DiscardUnknown, so it
answers HTTP 500 Error decode request body. That proto has not changed since it
was ported from Gitea in March 2024, and there is no issue open for it. Pinning
back to @actions/artifact 6.1 is not an option either, because skipArchive —
which keeps the HTML viewer artifact from being double-zipped — arrived in the
same 6.2 release.

So full mode now treats the upload as a warning rather than a failed run; the PR
comment carries the diff regardless. diff-only and comment-only pass results
between jobs as artifacts and stay GitHub-only until Forgejo accepts the field.

.forgejo/workflows/test-nix-diff-action.yml exercises the action here. Adding it
also stops Forgejo from picking up .github/workflows, whose runs-on: ubuntu-latest
jobs had been failing on this instance.

Makes the action usable from Forgejo Actions, not only GitHub Actions. Verified end to end on this instance: run 5 posts the comment above using the automatic workflow token, with no extra secret. Forgejo Runner already exposes GitHub-compatible event variables, so the action reached the right runner; what it got wrong was every URL it built. - Comment and compare links were hardcoded to `github.com`; they now come from `GITHUB_SERVER_URL` via the action context. - The "View diff as HTML" link used `GITHUB_RUN_ID`. On Forgejo that is a global database id (3516 for run 5 here, which 404s); run pages are addressed by the repository-scoped index in `GITHUB_RUN_NUMBER`. - Minimizing outdated comments is skipped on Forgejo, which has no GraphQL API, so those comments stay visible instead of failing the run. Artifacts cannot work on Forgejo today. `@actions/artifact` 6.2 and later send a `mime_type` field in `CreateArtifact`; Forgejo's `CreateArtifactRequest` protobuf defines fields 1-5 only and its handler unmarshals without `DiscardUnknown`, so it answers HTTP 500 `Error decode request body`. That proto has not changed since it was ported from Gitea in March 2024, and there is no issue open for it. Pinning back to `@actions/artifact` 6.1 is not an option either, because `skipArchive` — which keeps the HTML viewer artifact from being double-zipped — arrived in the same 6.2 release. So full mode now treats the upload as a warning rather than a failed run; the PR comment carries the diff regardless. `diff-only` and `comment-only` pass results between jobs as artifacts and stay GitHub-only until Forgejo accepts the field. `.forgejo/workflows/test-nix-diff-action.yml` exercises the action here. Adding it also stops Forgejo from picking up `.github/workflows`, whose `runs-on: ubuntu-latest` jobs had been failing on this instance.

natsukium added 1 commit

2026-09-19 16:15:00 +09:00

feat: run on Forgejo Actions as well as GitHub Actions

Test nix-diff-action / environment (pull_request) Successful in 0s

Details

Test nix-diff-action / full (pull_request) Failing after 53s

Details

baaa710cb4

Forgejo Runner exposes GitHub-compatible event variables, so the action
already reached the right runner; what it got wrong was every URL it
built. Comment and compare links were hardcoded to github.com instead of
GITHUB_SERVER_URL, and the run link used GITHUB_RUN_ID, which on Forgejo
is a global database id rather than the repository-scoped index its run
pages are addressed by.

@actions/artifact refuses any host but github.com before it ever touches
ACTIONS_RESULTS_URL, which Forgejo serves compatibly. Vendoring a patched
copy would tie this action's releases to upstream's, so only the host
guard's input is masked while every service URL stays Forgejo's.

Minimizing outdated comments is skipped on Forgejo because it has no
GraphQL API; the comments stay visible rather than failing the run.

natsukium added 1 commit

2026-09-19 16:26:07 +09:00

fix: keep Forgejo runs green when artifact upload is impossible

Test nix-diff-action / environment (pull_request) Successful in 1s

Details

Test nix-diff-action / full (pull_request) Successful in 10s

Details

e06bfccbe5

@actions/artifact 6.2 and later send a mime_type field in CreateArtifact.
Forgejo's CreateArtifactRequest protobuf defines no such field and its
handler unmarshals without DiscardUnknown, so it rejects the request with
HTTP 500 rather than ignoring the unknown field. Pinning back to 6.1 is
not an option because skipArchive, which keeps the HTML viewer artifact
from being double-zipped, arrived in the same release.

Full mode's real output is the PR comment, which already carries the
diff, so the upload is now a warning there instead of a failed run. The
host guard bypass is gone with it: getting past that check only moved the
failure one request further along. diff-only and comment-only hand
results between jobs as artifacts and stay GitHub-only until Forgejo
accepts the field.

natsukium added 1 commit

2026-09-19 16:26:48 +09:00

test: exercise the Forgejo comment path unconditionally

Test nix-diff-action / full (pull_request) Successful in 9s

Details

6105aa0717

A pull request that changes no derivation would otherwise skip the
comment, leaving the Forgejo comment API path untested.

forgejo-actions commented

2026-09-19 16:26:58 +09:00

Nix Diff

Compare changes

devShell

Attribute: devShells.x86_64-linux.default

Diff Output

<<< /nix/store/mg75d77v92ggczjfbi3aq1gf2p5hh7kf-nix-shell.drv
>>> /nix/store/mg75d77v92ggczjfbi3aq1gf2p5hh7kf-nix-shell.drv

PATHS: 3943 -> 3943 (+0, -0)
SIZE: 14.4 MiB -> 14.4 MiB
DIFF: 0 bytes

_{Generated by nix-diff-action using dix}

## Nix Diff [Compare changes](https://git.natsukium.com/natsukium/nix-diff-action/compare/92ef45c2e2b793e14b981b57f972bcdd5da71ee3...6105aa071770d7c24a4f00b6a81b23c74293300f) ### devShell **Attribute**: `devShells.x86_64-linux.default` <details> <summary>Diff Output</summary> ``` <<< /nix/store/mg75d77v92ggczjfbi3aq1gf2p5hh7kf-nix-shell.drv >>> /nix/store/mg75d77v92ggczjfbi3aq1gf2p5hh7kf-nix-shell.drv PATHS: 3943 -> 3943 (+0, -0) SIZE: 14.4 MiB -> 14.4 MiB DIFF: 0 bytes ``` </details> --- <sub>Generated by [nix-diff-action](https://github.com/natsukium/nix-diff-action) using [dix](https://github.com/manic-systems/dix)</sub>

Test nix-diff-action / full (pull_request) Successful in 9s

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git fetch -u origin feat/forgejo-support:feat/forgejo-support

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git switch main

git merge --no-ff feat/forgejo-support

git switch feat/forgejo-support

git rebase main

git switch main

git merge --ff-only feat/forgejo-support

git switch feat/forgejo-support

git rebase main

git switch main

git merge --no-ff feat/forgejo-support

git switch main

git merge --squash feat/forgejo-support

git switch main

git merge --ff-only feat/forgejo-support

git switch main

git merge feat/forgejo-support

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feat: run on Forgejo Actions as well as GitHub Actions #1

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