ci(ros): use matching branch for px4-ros2-interface-lib (#26781)

* ci(ros): use matching branch for px4-ros2-interface-lib

When running on release branches, the ROS integration tests now
check if a matching branch exists in px4-ros2-interface-lib and
clone it instead of always using main. This prevents build failures
caused by uORB message divergence between main and release branches.

Fixes https://github.com/Auterion/px4-ros2-interface-lib/issues/184

Signed-off-by: Ramon Roche <mrpollo@gmail.com>

* ci(ros): dispatch release branch creation to px4-ros2-interface-lib

Add a standalone workflow triggered by the create event that fires a
repository_dispatch to Auterion/px4-ros2-interface-lib when a
release/X.Y branch is created. Also supports manual workflow_dispatch.

Signed-off-by: Ramon Roche <mrpollo@gmail.com>

* ci(ros): add empty permissions block to dispatch workflow

Fixes code scanning alert about missing GITHUB_TOKEN permissions.
This workflow only uses a PAT secret, not GITHUB_TOKEN, so no
permissions are needed.

Signed-off-by: Ramon Roche <mrpollo@gmail.com>

---------

Signed-off-by: Ramon Roche <mrpollo@gmail.com>

.github/workflows/ros_integration_tests.yml

@@ -89,7 +89,15 @@ jobs:
         . /opt/ros/galactic/setup.bash
         mkdir -p /opt/px4_ws/src
         cd /opt/px4_ws/src
-        git clone --recursive https://github.com/Auterion/px4-ros2-interface-lib.git
+        BRANCH="${GITHUB_HEAD_REF:-$GITHUB_REF_NAME}"
+        REPO_URL="https://github.com/Auterion/px4-ros2-interface-lib.git"
+        if git ls-remote --heads "$REPO_URL" "$BRANCH" | grep -q "$BRANCH"; then
+          echo "Cloning px4-ros2-interface-lib with matching branch: $BRANCH"
+          git clone --recursive --branch "$BRANCH" "$REPO_URL"
+        else
+          echo "Branch '$BRANCH' not found in px4-ros2-interface-lib, using default (main)"
+          git clone --recursive "$REPO_URL"
+        fi
         # Ignore python packages due to compilation issue (can be enabled when updating ROS)
         touch px4-ros2-interface-lib/px4_ros2_py/COLCON_IGNORE || true
         touch px4-ros2-interface-lib/examples/python/COLCON_IGNORE || true

.github/workflows/sync_release_to_ros2_interface_lib.yml

@@ -0,0 +1,43 @@
+name: Sync release branch to px4-ros2-interface-lib
+
+on:
+  create:
+  workflow_dispatch:
+    inputs:
+      branch:
+        description: 'Release branch name (e.g. release/1.18)'
+        required: true
+        type: string
+
+permissions: {}
+
+jobs:
+  notify-interface-lib:
+    if: >-
+      github.repository == 'PX4/PX4-Autopilot' &&
+      (
+        (github.event_name == 'create' && github.ref_type == 'branch' && startsWith(github.ref_name, 'release/')) ||
+        github.event_name == 'workflow_dispatch'
+      )
+    runs-on: ubuntu-latest
+    steps:
+      - name: Determine branch name
+        id: params
+        run: |
+          if [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
+            BRANCH="${{ inputs.branch }}"
+          else
+            BRANCH="${{ github.ref_name }}"
+          fi
+          echo "branch=$BRANCH" >> "$GITHUB_OUTPUT"
+          echo "Dispatching for branch: $BRANCH"
+
+      - name: Dispatch release branch creation
+        run: |
+          BRANCH="${{ steps.params.outputs.branch }}"
+          curl -s -f -X POST \
+            -H "Authorization: token ${{ secrets.PX4BUILTBOT_PERSONAL_ACCESS_TOKEN }}" \
+            -H "Accept: application/vnd.github.v3+json" \
+            https://api.github.com/repos/Auterion/px4-ros2-interface-lib/dispatches \
+            -d "{\"event_type\":\"px4_release_branch\",\"client_payload\":{\"branch\":\"$BRANCH\"}}"
+          echo "Dispatched px4_release_branch event for $BRANCH"