ci: add a notification for Key4hep when the build fails (#5265)

Add a notification for Key4hep when the build fails

Author: jmcarcell

.github/workflows/report.yml

@@ -136,3 +136,13 @@ jobs:
             echo "{\"text\":\"External pipeline failure in ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY}/actions/runs/${GITHUB_RUN_ID}?pr=${{steps.get-pr-number.outputs.PR_NUMBER}}.\"}" | tee data.json
             curl -X POST -H 'Content-type: application/json' --data "@data.json" ${EIC_EPIC_MATTERMOST_HOOK_URL}
           fi
+
+      - name: Post failure notifications to Key4hep mattermost
+        if: steps.get-pr-number.outcome == 'success'
+        env:
+          KEY4HEP_MATTERMOST_HOOK_URL: ${{secrets.KEY4HEP_MATTERMOST_HOOK_URL}}
+        run: |
+          if [ -f comment-51-key4hep-external-failure.md ] ; then
+            echo "{\"text\":\"External pipeline failure in ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY}/actions/runs/${GITHUB_RUN_ID}?pr=${{steps.get-pr-number.outputs.PR_NUMBER}}.\"}" | tee data.json
+            curl -X POST -H 'Content-type: application/json' --data "@data.json" ${KEY4HEP_MATTERMOST_HOOK_URL}
+          fi