Warn via issue if overnight benchmarks fail (#5432)

* Include a warning step for overnight benchmarking.

* Fix for failure warning script.

* Better formatting of warning issue title.

* What's new entry.

.github/workflows/benchmarks_run.yml

@@ -84,6 +84,7 @@ jobs:
           python benchmarks/bm_runner.py branch origin/${{ github.base_ref }}
 
       - name: Run overnight benchmarks
+        id: overnight
         if: ${{ github.event_name != 'pull_request' }}
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -99,6 +100,17 @@ jobs:
             python benchmarks/bm_runner.py overnight $first_commit
           fi
 
+      - name: Warn of failure
+        if: >
+          failure() &&
+          steps.overnight.outcome == 'failure'
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          title="Overnight benchmark workflow failed: \`${{ github.run_id }}\`"
+          body="Generated by GHA run [\`${{github.run_id}}\`](https://github.com/${{github.repository}}/actions/runs/${{github.run_id}})"
+          gh issue create --title "$title" --body "$body" --label "Bot" --label "Type: Performance" --repo $GITHUB_REPOSITORY
+
       - name: Upload any benchmark reports
         uses: actions/upload-artifact@v3
         with:

docs/src/whatsnew/latest.rst

@@ -89,6 +89,10 @@ This document explains the changes made to Iris for this release
    of how the pull request changes affect performance. (feature branch:
    :pull:`5431`)
 
+#. `@trexfeathers`_ added a catch to the overnight benchmark workflow to raise
+   an issue if the overnight run fails - this was previously an 'invisible'
+   problem. (feature branch: :pull:`5432`)
+
 
 .. comment
     Whatsnew author names (@github name) in alphabetical order. Note that,