feat(api): add new /repos/{owner}/{repo}/actions/runs/{run_id}/cancel API endpoint (#12957)

This new API endpoint makes it possible to cancel action runs via the API. Previously this was only natively possible through the UI, the same `CancelRun` func has been reused for this feature.

### Tests for Go changes

- I added test coverage for Go changes...
  - [ ] in their respective `*_test.go` for unit tests.
  - [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I ran...
  - [x] `make pr-go` before pushing

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Features
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/12957): <!--number 12957 --><!--line 0 --><!--description ZmVhdChhcGkpOiBhZGQgbmV3IGAvcmVwb3Mve293bmVyfS97cmVwb30vYWN0aW9ucy9ydW5zL3tydW5faWR9L2NhbmNlbGAgQVBJIGVuZHBvaW50-->feat(api): add new `/repos/{owner}/{repo}/actions/runs/{run_id}/cancel` API endpoint<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/12957
Reviewed-by: limiting-factor <limiting-factor@noreply.codeberg.org>
Reviewed-by: Andreas Ahlenstorf <aahlenst@noreply.codeberg.org>
Reviewed-by: Mathieu Fenniak <mfenniak@noreply.codeberg.org>

routers/api/v1/api.go

@@ -1256,6 +1256,7 @@ func Routes() *web.Route {
 						m.Get("", repo.ListActionRuns)
 						m.Get("/{run_id}", repo.GetActionRun)
 						m.Delete("/{run_id}", reqToken(), reqAdmin(unit.TypeActions), repo.DeleteActionRun)
+						m.Post("/{run_id}/cancel", reqToken(), reqRepoWriter(unit.TypeActions), repo.CancelActionRun)
 						m.Get("/{run_id}/jobs", repo.ListActionRunJobs)
 						m.Get("/{run_id}/logs", repo.GetActionRunLogs)
 						m.Get("/{run_id}/artifacts", repo.ListActionRunArtifacts)

routers/api/v1/repo/action.go

@@ -1095,6 +1095,67 @@ func DeleteActionRun(ctx *context.APIContext) {
 	ctx.Status(http.StatusNoContent)
 }
 
+// CancelActionRun cancels a pending or running workflow run.
+func CancelActionRun(ctx *context.APIContext) {
+	// swagger:operation POST /repos/{owner}/{repo}/actions/runs/{run_id}/cancel repository CancelActionRun
+	// ---
+	// summary: Cancel a pending or running workflow run.
+	// description: >
+	//   Cancel a particular workflow run. Pending or running jobs of the run are cancelled. A run that has
+	//   already finished, whether cancelled, failed, skipped or succeeded, is left unchanged.
+	//   In both cases the endpoint responds with HTTP 204.
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// - name: run_id
+	//   in: path
+	//   description: ID of the workflow run
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// responses:
+	//   "204":
+	//     description: Workflow run has been cancelled
+	//   "403":
+	//     "$ref": "#/responses/forbidden"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+
+	run, err := actions_model.GetRunByID(ctx, ctx.ParamsInt64(":run_id"))
+	if err != nil {
+		if errors.Is(err, util.ErrNotExist) {
+			ctx.Error(http.StatusNotFound, "GetRunById", err)
+			return
+		}
+
+		ctx.Error(http.StatusInternalServerError, "GetRunByID", err)
+		return
+	}
+
+	if ctx.Repo.Repository.ID != run.RepoID {
+		ctx.Error(http.StatusNotFound, "GetRunById", util.ErrNotExist)
+		return
+	}
+
+	err = actions_service.CancelRun(ctx, run)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "CancelRun", err)
+		return
+	}
+
+	ctx.Status(http.StatusNoContent)
+}
+
 // ListActionRunJobs return a filtered list of jobs that belong to a single workflow run
 func ListActionRunJobs(ctx *context.APIContext) {
 	// swagger:operation GET /repos/{owner}/{repo}/actions/runs/{run_id}/jobs repository ListActionRunJobs