Ci: Run different jobs on push or mr

.gitlab-ci.yml

@@ -11,9 +11,38 @@ stages:
       - .gradle/
       - ~/.gradle/caches/
 
+.on-commit: &on-commit
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+      when: never
+    - if: '$CI_COMMIT_BRANCH'
+      allow_failure: true
+
+.on-mr: &on-mr
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+      allow_failure: true   # deactivate after all issues (shown by checkstyle) have been resolved
+
 # Jobs
 checkstyle:
-    <<: *gradle-cache
+    <<: [*gradle-cache, *on-commit]
+    stage: lint
+    image: gradle:9.3.1-jdk25
+    script:
+        - gradle checkstyleMain checkstyleTest
+    allow_failure: true
+    artifacts:
+        when: always
+        paths:
+            - build/reports/checkstyle/main.html
+            - build/reports/checkstyle/main.xml
+            - build/reports/checkstyle/test.html
+            - build/reports/checkstyle/test.xml
+        expose_as: 'Checkstyle Report'
+        expire_in: 1 week
+
+checkstyle-mr:
+    <<: [*gradle-cache, *on-mr]
     stage: lint
     image: gradle:9.3.1-jdk25
     script:
@@ -28,16 +57,16 @@ checkstyle:
             - build/reports/checkstyle/test.xml
         expose_as: 'Checkstyle Report'
         expire_in: 1 week
-    rules:
-        - when: manual
 
 checkstyle-report:
     stage: report
     image: python:3.14
     needs:
-        - job: checkstyle
+        - job: checkstyle-mr
           artifacts: true
           optional: true
+    rules:
+        - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
     script:
         - python3 scripts/convert-checkstyle-gl-report.py
     artifacts:
@@ -54,4 +83,7 @@ compile-check:
         - gradle compileTestJava
     needs: []
     rules:
-        - when: manual
+        - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+          allow_failure: false
+        - if: '$CI_COMMIT_BRANCH'
+          allow_failure: false