Enhance update truth data workflow to create a uniquely named branch …

…to update *-ref branches and commit/append to a log file that tracks the reasons for updating the truth data. This is done to ensure that the *-ref branch testing workflow run that actually updates the truth data is always run even if there are no other changes to the METplus branch since the last update, e.g. when a change to another component like MET warrants the truth data update

.github/workflows/update_truth.yml

@@ -32,6 +32,7 @@ jobs:
           fetch-depth: 0
           token: ${{ secrets.METPLUS_BOT_TOKEN }}
       - name: Resolve conflicts between branch and branch-ref
+        id: resolve_conflicts
         run: |
           branch_name=${{ env.branch_name }}
           cd ${GITHUB_WORKSPACE}
@@ -43,17 +44,43 @@ jobs:
           echo ${branch_name}-ref does exist -- update it
           git config --global user.name "metplus-bot"
           git config --global user.email "[email protected]"
+          # checkout branch (develop or main_vX.Y)
           echo git checkout ${branch_name}
           git checkout ${branch_name}
+
+          # merge -ref branch into branch (favoring branch changes)
           echo git merge -s ours origin/${branch_name}-ref
           git merge -s ours origin/${branch_name}-ref
+
+          # push changes to branch (develop or main_vX.Y)
           echo git push origin ${branch_name}
           git push origin ${branch_name}
 
+          # create unique branch name to update *-ref branch
+          update_branch=update_${branch_name}_$(uuidgen | cut -d "-" -f1)
+          echo "update_branch=${update_branch}" >> $GITHUB_OUTPUT
+
+          # create update branch from branch (develop or main_vX.Y)
+          echo git checkout -b ${update_branch}
+          git checkout -b ${update_branch}
+
+          # create or append to file to track truth data changes
+          # and ensure that PR merge into *-ref branch triggered testing workflow
+          change_log_path=.github/update_truth_change_log.txt
+          change_entry="[$(date +%Y%m%d_%H:%M:%S) ${branch_name}] ${{ github.event.inputs.pull_requests }} - ${{ github.event.inputs.change_summary }}"
+          echo "${change_entry}" >> ${change_log_path}
+          echo git commit ${change_log_path}
+          git commit -m "added entry to update truth change log: ${branch_name} ${{ github.event.inputs.pull_requests }}" ${change_log_path}
+          cmd="git push origin ${update_branch}"
+          echo $cmd
+          $cmd
+
+      # create pull request from $HEAD into $BASE
       - name: Create Pull Request
-        run: gh pr create --base $BASE --body "$BODY" --title "$TITLE"
+        run: gh pr create --head $HEAD --base $BASE --body "$BODY" --title "$TITLE"
         env:
           GH_TOKEN: ${{ github.token }}
+          HEAD: ${{ steps.resolve_conflicts.outputs.update_branch }}
           BASE: ${{ env.branch_name }}-ref
           BODY: ${{ github.event.inputs.change_summary }}<br/>Created by @${{ github.actor}}
           TITLE: Update ${{ env.branch_name }}-ref after ${{ github.event.inputs.pull_requests }}