initial: action/cascade-from @v1

2026-05-06 08:07:33 -05:00
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+# action/cascade-from
+
+Composite Gitea Action that bumps a `FROM <image>:<tag>` line in a target
+repo's Dockerfile, then commits and pushes. The target repo's CI fires on
+that push, rebuilding against the new base.
+
+The only consumer today is `fritzlab/base` triggering a rebuild of
+`fritzlab/runner` whenever the base image changes. This action is the
+generalization of that pattern.
+
+## Usage
+
+```yaml
+- uses: actions/checkout@v4
+- uses: https://code.fritzlab.net/action/image-build@v1
+  with:
+    image: code.fritzlab.net/fritzlab/base
+- uses: https://code.fritzlab.net/action/image-push@v1
+  with:
+    image: code.fritzlab.net/fritzlab/base
+    token: ${{ secrets.CI_BOT_TOKEN }}
+    org: fritzlab
+    name: base
+- uses: https://code.fritzlab.net/action/cascade-from@v1
+  with:
+    target-repo: fritzlab/runner
+    image: code.fritzlab.net/fritzlab/base
+    token: ${{ secrets.CI_BOT_TOKEN }}
+```
+
+## Inputs
+
+| Name | Required | Default | Description |
+|---|---|---|---|
+| `target-repo` | yes | — | Target repo to edit (e.g. `fritzlab/runner`). |
+| `image` | yes | — | Image to look for in the FROM line. |
+| `tag` | no | `github.run_number` | New tag to write into FROM. |
+| `file` | no | `Dockerfile` | File inside target-repo to edit. |
+| `token` | yes | — | `CI_BOT_TOKEN` with write to target-repo. |
+| `host` | no | `code.fritzlab.net` | Gitea host without protocol. |
+| `message` | no | `bump <name> to #<tag>` | Commit message override. |
+
+## Behavior
+
+1. Shallow-clone target-repo to a temp dir.
+2. `sed -i "s|^FROM <image>:.*|FROM <image>:<tag>|" <file>`.
+3. Verify sed actually matched a line — fail if not (catches typos in image
+   name).
+4. If no diff (target already on this tag): exit 0 silently.
+5. Otherwise commit + push to `main` with rebase-on-conflict retry up to
+   3 times.
+
+## Notes
+
+- Only matches lines starting with `FROM <image>:` (anchored to start). Multi-stage
+  Dockerfiles with a non-anchored `FROM <image>:tag AS stage` will be missed —
+  add the AS-aware pattern as a future enhancement if needed.
+- Pushing to target-repo triggers its CI, which produces a new image of its
+  own. There is no end-to-end orchestration: the upstream repo's CI completes
+  the moment cascade-from pushes, regardless of whether the downstream build
+  succeeds.