task: add fork-sync github action workflow

with scheduled trigger to sync every hour.

Signed-off-by: Michael Zeevi <[email protected]>

.github/workflows/fork-sync.yaml

@@ -0,0 +1,39 @@
+name: Sync Fork
+
+on:
+  schedule:
+  - cron: '0 0 * * *'  # nightly
+  workflow_dispatch:   # enable manual trigger
+
+jobs:
+  lookup-most-recent-release-branch:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Lookup most recent release branch
+      id: lookup-most-recent-release-branch
+      run: |
+        git fetch --all
+        echo most_recent_release_branch=$(git branch --remotes --sort refname | grep network-operator- | tail -n 1 | cut -d '/' -f 2-) >> $GITHUB_OUTPUT
+    outputs:
+      most_recent_release_branch: ${{ steps.lookup-most-recent-release-branch.outputs.most_recent_release_branch }}
+
+  sync-fork:
+    runs-on: ubuntu-latest
+    needs: lookup-most-recent-release-branch
+    strategy:
+      matrix:
+        branch:
+        - master
+        - ${{ needs.lookup-most-recent-release-branch.outputs.most_recent_release_branch }}  # if no release branch, this will fail silently
+    steps:
+    - uses: tgymnich/[email protected]
+      with:
+        owner: k8snetworkplumbingwg  # upstream
+        head: master                 # upstream
+        base: ${{ matrix.branch }}   # downstream
+        pr_title: 'task: Sync ${{ matrix.branch }} from upstream'
+        pr_message: 'Created by [${{ github.repository }} CI](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}) (*${{ github.job }}* job).'
+        retries: 2
+        retry_after: 10
+        ignore_fail: true