Add GHA workflow for opening PRs upstream (#116)

* Add file for opening PRs upstream

* Add HEAD_REF as environment variable

* Fill out code for making a new branch and opening a PR to upstream

* Add names for steps

* Fix yaml

* Fix yaml again

* Leave a comment on the old PR linking to the new one

* Add proper permissions for creating banches and opening PRs

* Fix YAML

Author: charleshofer

.github/workflows/rocm-open-upstream-pr.yml

@@ -0,0 +1,39 @@
+name: ROCm Open Upstream PR
+on:
+  pull_request:
+    types: [ labeled ]
+    branches: [ rocm-main ]
+jobs:
+  open-upstream:
+    if: ${{ github.event.label.name == 'open-upstream' }}
+    permissions:
+      contents: write
+      pull-requests: write
+    runs-on: ubuntu-latest
+    outputs:
+      new-pr-link: ${{ steps.create-pr.outputs.link }}
+    env:
+      NEW_BRANCH_NAME: "${{ github.head_ref }}-upstream"
+      NEW_PR_TITLE: "[ROCM] ${{ github.event.pull_request.title }}"
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683  # v4.2.2
+      - name: Rebase code to main
+        run: |
+          git checkout -b $NEW_BRANCH_NAME ${{ github.head_ref }}
+          git rebase --onto main
+          git push origin HEAD
+      # TODO: Change the base of the PR to upstream main
+      - name: Create a PR to upstream
+        id: create-pr
+        run: |
+          echo link=$(gh pr create --repo rocm/jax --base main --head $NEW_BRANCH_NAME --title "$NEW_PR_TITLE" --body "${{ github.event.pull_request.body }}") >> "$GITHUB_OUTPUT"
+  comment-link:
+    needs: open-upstream
+    permissions:
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - name: Leave comment on old PR
+        run: gh pr comment ${{ github.event.pull_request.number }} --repo rocm/jax --body ${{ needs.open-upstream.outputs.new-pr-link.link }}
+