# Manifest Diff Report

The **manifest diff report** is a CI tool that summarizes which TheRock submodule SHAs changed between two commits. It runs automatically on every multi-arch CI run for `pull_request` and `push` events, and can also be invoked on demand via direct `workflow_dispatch` of [`manifest-diff.yml`](../../.github/workflows/manifest-diff.yml) or locally on the command line.

## Summary

TheRock is a CMake super-project pinned to a small set of top-level git submodules (`.gitmodules`), two of which (`rocm-libraries`, `rocm-systems`) are themselves superrepos containing further ROCm components under `projects/` and `shared/`. When a change in TheRock or in any of those upstream repos lands, it can be non-obvious which pointer(s) actually moved. The manifest diff report answers that question: for two TheRock commits (a **start** and an **end**), it walks the manifest produced by `generate_therock_manifest.py` — top-level submodules plus superrepo components — and produces an HTML page listing the new commit range on each one, with links back to the upstream repos.

The report is generated by [`build_tools/generate_manifest_diff_report.py`](../../build_tools/generate_manifest_diff_report.py) and uploaded to S3 by the [`manifest-diff.yml`](../../.github/workflows/manifest-diff.yml) reusable workflow.

## How it runs in CI

On `pull_request` and `push` events, [`multi_arch_ci.yml`](../../.github/workflows/multi_arch_ci.yml) invokes [`manifest-diff.yml`](../../.github/workflows/manifest-diff.yml) as a parallel sibling job. The reusable workflow auto-derives the **start** and **end** refs from the event payload — PR runs use the merge-base against the PR's base branch (rebase-safe via the GitHub Compare API); push runs use the branch tip before and after the push.

```mermaid
flowchart TD
    A[multi_arch_ci.yml fires] --> B{event_name}
    B -- pull_request --> P[merge-base via Compare API<br/>→ PR head SHA]
    B -- push --> U[branch tip before push<br/>→ new branch tip]
    P --> G[generate_manifest_diff_report.py]
    U --> G
    G --> O[upload_test_report_script.py]
    O --> H[S3 + step-summary link]
```

The sibling job is wired only for those two events because they're the ones whose payloads carry the implicit refs. A manual `workflow_dispatch` of `multi_arch_ci.yml` skips it; for ad-hoc runs, dispatch [`manifest-diff.yml`](../../.github/workflows/manifest-diff.yml) directly — it exposes the full ref input surface.

### Failure behavior

The reusable workflow sets `continue-on-error: ${{ github.event_name != 'workflow_dispatch' }}`:

- **Under CI** (`push` / `pull_request` from `multi_arch_ci.yml`): non-blocking — a script or API failure shows yellow on the run summary and never gates the build/test jobs running in parallel.
- **Under direct `workflow_dispatch`** of `manifest-diff.yml`: strict — real script regressions surface red, since the only reason to dispatch this workflow manually is to validate the script.

The upload and AWS-credentials steps are both gated on the report-generation step succeeding, so a failed report produces only the real error rather than a follow-on "no such file" upload failure.

### Where the report lives

The report is uploaded to S3 by [`upload_test_report_script.py`](../../build_tools/github_actions/upload_test_report_script.py) and linked from the job's step-summary tab. S3 layout, bucket selection, and credential routing (OIDC for base-repo, baseline credentials for fork PRs) are owned by [`workflow_outputs.md`](workflow_outputs.md) and [`s3_buckets.md`](s3_buckets.md).

## Running it manually

### `workflow_dispatch`

Trigger `TheRock Manifest Diff Report` on the [Actions page](https://github.com/ROCm/TheRock/actions/workflows/manifest-diff.yml). `end_ref` is required; pick exactly one of `pr_base_ref`, `find_last_run`, or `start_ref` to resolve the start (precedence: `pr_base_ref` > `find_last_run` > `start_ref`). See the `description:` fields on the inputs in [`manifest-diff.yml`](../../.github/workflows/manifest-diff.yml) for the authoritative reference.

### Local CLI

See [`generate_manifest_diff_report.py`](../../build_tools/generate_manifest_diff_report.py) and run with `--help` for usage. Set `GITHUB_TOKEN` (any token with `public_repo` read scope) before running to avoid GitHub's 60 req/hr unauthenticated rate limit.

## Out of scope

External orchestrator workflows in `rocm-libraries` / `rocm-systems` that drive TheRock's reusable workflows via `setup_multi_arch.yml`'s `external_repo` input, and the rockrel release-driver flow (via `multi_arch_release.yml`), currently produce no manifest-diff; extending the report to those callers is tracked in #5219.

## Code map

| File                                                                                                                       | Role                                                                     |
| -------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------ |
| [`.github/workflows/manifest-diff.yml`](../../.github/workflows/manifest-diff.yml)                                         | Reusable workflow: derives refs from caller event, runs script, uploads. |
| [`.github/workflows/multi_arch_ci.yml`](../../.github/workflows/multi_arch_ci.yml)                                         | Hosts the `manifest_diff` sibling job that calls `manifest-diff.yml`.    |
| [`build_tools/generate_manifest_diff_report.py`](../../build_tools/generate_manifest_diff_report.py)                       | Resolves start/end SHAs, walks submodules, renders the HTML report.      |
| [`build_tools/github_actions/github_actions_api.py`](../../build_tools/github_actions/github_actions_api.py)               | `gha_query_last_workflow_run()` shared helper used by `--find-last-run`. |
| [`build_tools/github_actions/upload_test_report_script.py`](../../build_tools/github_actions/upload_test_report_script.py) | S3 upload + step-summary link (shared with test reports).                |

## Related

- [`ci_overview.md`](ci_overview.md) — overall multi-arch CI architecture.
- [`workflow_outputs.md`](workflow_outputs.md) — S3 layout used by the upload step.
- [`github_actions_debugging.md`](github_actions_debugging.md) — debugging GitHub Actions runs.