Improve CI to a more finegrained CI

.github/workflows/check_indentation.yml

@@ -32,9 +32,6 @@ name: t8code indentation check
 
 on:
   merge_group:
-  push:
-    branches:
-      - main
   pull_request:
   workflow_dispatch: # Be able to trigger this manually on github.com
   # Run every night at 1:05

.github/workflows/spell_check.yml

@@ -2,9 +2,6 @@ name: spell_check
 
 on:
   merge_group:
-  push:
-    branches:
-      - main
   pull_request:
   workflow_dispatch: # Be able to trigger this manually on github.com
 

.github/workflows/tests_cmake_testsuite.yml

@@ -32,19 +32,69 @@ name: t8code CMake testsuite
 
 on:
   merge_group:
-  push:
-    branches:
-      - main
   pull_request:
   workflow_dispatch: # Be able to trigger this manually on github.com
   # Run every night at 1:10
   schedule:
       - cron:  '10 1 * * *'
 
+# The CI pipeline should:
+# - fully run in the merge queue with the full test suite
+# - not run on Draft PRs
+# - run on Draft PRs, IF the latest commit message contains '[run CI]'
+# - run on scheduled runs for the DLR-AMR/t8code repository
+# - run on all other pull request events
+# These conditions are checked in the fine_grained_trigger job. If it completes successfully, it triggers the preparation job, 
+# which triggers the actual tests. 
+# The job to build the tarball is only triggered on merge_group events for the DLR-AMR/t8code repository.
+
 jobs:
+
+  fine_grained_trigger:
+    runs-on: ubuntu-latest
+    outputs:
+      run_ci: ${{ steps.set_run_ci.outputs.RUN_CI }}
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        repository: ${{ github.event.pull_request.head.repo.full_name }}
+        ref: ${{ github.event.pull_request.head.ref }}
+        fetch-depth: 0
+    - name: set the run_ci variable for the testsute
+      id: set_run_ci
+      run: |
+        if [[ "${{ github.event_name }}" == "schedule" && "${{ github.repository }}" == "DLR-AMR/t8code" ]]; then
+          echo "Scheduled run for DLR-AMR/t8code, proceeding with CI."
+          echo "RUN_CI=true" >> $GITHUB_OUTPUT
+          exit 0
+        fi
+        latest_commit_message=$(git log -1 --pretty=%B)
+        echo "Latest commit message: $latest_commit_message"
+        if [[ "${{ github.event_name }}" != "schedule" ]]; then
+          if [[ "${{ github.event.pull_request.draft }}" == "false" ]]; then
+            echo "Not a draft PR, proceeding with CI."
+            echo "RUN_CI=true" >> $GITHUB_OUTPUT
+            exit 0
+          elif [[ "${{ github.event.pull_request.draft }}" == "true" && "$latest_commit_message" == *"[run CI]"* ]]; then
+            echo "Draft PR with '[run CI]' in the latest commit message, proceeding with CI."
+            echo "RUN_CI=true" >> $GITHUB_OUTPUT
+            exit 0
+          else
+            echo "Draft PR without '[run CI]' in the latest commit message, skipping CI."
+            echo "RUN_CI=false" >> $GITHUB_OUTPUT
+            exit 0
+          fi
+        else
+          echo "Conditions not met, skipping CI."
+          echo "RUN_CI=false" >> $GITHUB_OUTPUT
+          exit 0
+        fi
+
   # Preparation step for tests. Repo is cloned and sc + p4est are compiled with and without MPI.
   preparation:
-    if: (github.event_name == 'schedule' && github.repository == 'DLR-AMR/t8code') || (github.event_name != 'schedule')
+    needs: [fine_grained_trigger]
+    secrets: inherit
+    if: needs.fine_grained_trigger.outputs.run_ci == 'true'
     uses: ./.github/workflows/tests_cmake_preparation.yml
     strategy:
       fail-fast: false
@@ -60,7 +110,6 @@ jobs:
 
   # Run parallel tests for sc and p4est with and without MPI
   sc_p4est_tests:
-    if: ((github.event_name == 'schedule' && github.repository == 'DLR-AMR/t8code') || (github.event_name != 'schedule'))
     needs: preparation
     uses: ./.github/workflows/tests_cmake_sc_p4est.yml
     strategy:
@@ -75,7 +124,7 @@ jobs:
 
   # Run t8code tests with and without MPI and in serial and debug mode
   t8code_tests:
-    if: (github.event_name == 'schedule' && github.repository == 'DLR-AMR/t8code') || (github.event_name != 'schedule')
+    needs: preparation
     uses: ./.github/workflows/tests_cmake_t8code.yml
     strategy:
       fail-fast: false
@@ -84,7 +133,6 @@ jobs:
         BUILD_TYPE: [Debug, Release]
         include: 
           - MAKEFLAGS: -j4
-    needs: preparation
     with:
       MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
       MPI: ${{ matrix.MPI }}
@@ -93,7 +141,7 @@ jobs:
 
   # Run t8code linkage tests with and without MPI and in serial and debug mode
   t8code_linkage_tests:
-    if: (github.event_name == 'schedule' && github.repository == 'DLR-AMR/t8code') || (github.event_name != 'schedule')
+    needs: preparation
     uses: ./.github/workflows/tests_cmake_t8code_linkage.yml
     strategy:
       fail-fast: false
@@ -102,7 +150,6 @@ jobs:
         BUILD_TYPE: [Debug, Release]
         include: 
           - MAKEFLAGS: -j4
-    needs: preparation
     with:
       MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
       MPI: ${{ matrix.MPI }}
@@ -111,7 +158,7 @@ jobs:
 
   # Run t8code linkage tests with and without MPI and in serial and debug mode
   t8code_api_tests:
-    if: (github.event_name == 'schedule' && github.repository == 'DLR-AMR/t8code') || (github.event_name != 'schedule')
+    needs: preparation
     uses: ./.github/workflows/tests_cmake_t8code_api.yml
     strategy:
       fail-fast: false
@@ -120,7 +167,6 @@ jobs:
         BUILD_TYPE: [Debug, Release]
         include: 
           - MAKEFLAGS: -j4
-    needs: preparation
     with:
       MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
       MPI: ${{ matrix.MPI }}
@@ -129,7 +175,9 @@ jobs:
 
   # Run t8code tests with shipped submodules. This test is only for the build system, so only one config is tested.
   t8code_w_shipped_submodules_tests:
-    if: (github.event_name == 'schedule' && github.repository == 'DLR-AMR/t8code') || (github.event_name != 'schedule')
+    needs: fine_grained_trigger
+    secrets: inherit
+    if: ${{ needs.fine_grained_trigger.outputs.run_ci == 'true' }}
     uses: ./.github/workflows/tests_cmake_t8code_w_shipped_submodules.yml
     with:
       MAKEFLAGS: -j4
@@ -138,7 +186,7 @@ jobs:
       TEST_LEVEL: ${{ github.event_name == 'pull_request' && 1 || 0 }} # Set TEST_LEVEL to 1 if the event is a PR, otherwise 0.
 
   t8code_tarball:
-    if: (github.event_name == 'schedule' && github.repository == 'DLR-AMR/t8code') || (github.event_name != 'schedule')
+    if: github.event.pull_request == false
     uses: ./.github/workflows/build_cmake_tarball.yml
     needs: [preparation, sc_p4est_tests, t8code_tests, t8code_linkage_tests, t8code_api_tests, t8code_w_shipped_submodules_tests]
     with: