[Build] Skip scheduled I/Y-build if nothing has changed since last build

Fixes #678

Author: HannesWell

JenkinsJobs/Builds/I_build.groovy

@@ -208,6 +208,9 @@ spec:
             }
 		}
 	  stage('Tag Build Inputs'){
+          environment {
+            ABORT_IF_NO_CHANGES = "${!currentBuild.getBuildCauses('hudson.triggers.TimerTrigger$TimerTriggerCause').isEmpty()}" // true, if triggered by timer
+          }
           steps {
                   sshagent (['git.eclipse.org-bot-ssh', 'github-bot-ssh', 'projects-storage.eclipse.org-bot-ssh']) {
                     sh \'\'\'
@@ -220,6 +223,16 @@ spec:
                         fi
                     \'\'\'
                   }
+                  script {
+                    if (env.ABORT_IF_NO_CHANGES && fileExists("${WORKSPACE}/noChanges")) {
+                      emailext subject: "${env.BUILD_VERSION} I-Build: ${env.BUILD_IID.trim()} - BUILD SKIPPED",
+                        body: "The scheduled build was skipped because no changes have been made since the last successful build.<br>For details see <a href='${BUILD_URL}console'>${BUILD_URL}console</a><br>",
+                        to: '[email protected]',
+                        from: '[email protected]'
+                      currentBuild.result = 'ABORTED'
+                      error('Abort scheduled build due to no changes')
+                    }
+                  }
             }
 		}
 	  stage('Aggregator maven build'){

JenkinsJobs/YBuilds/Y_build.groovy

@@ -205,6 +205,9 @@ spec:
             }
 		}
 	  stage('Tag Build Inputs'){
+          environment {
+            ABORT_IF_NO_CHANGES = "${!currentBuild.getBuildCauses('hudson.triggers.TimerTrigger$TimerTriggerCause').isEmpty()}" // true, if triggered by timer
+          }
           steps {
                   sshagent (['git.eclipse.org-bot-ssh', 'github-bot-ssh', 'projects-storage.eclipse.org-bot-ssh']) {
                     sh \'\'\'
@@ -217,6 +220,16 @@ spec:
                         fi
                     \'\'\'
                   }
+                  script {
+                    if (env.ABORT_IF_NO_CHANGES && fileExists("${WORKSPACE}/noChanges")) {
+                      emailext subject: "${env.BUILD_VERSION} I-Build: ${env.BUILD_IID.trim()} - BUILD SKIPPED",
+                        body: "The scheduled build was skipped because no changes have been made since the last successful build.<br>For details see <a href='${BUILD_URL}console'>${BUILD_URL}console</a><br>",
+                        to: '[email protected]',
+                        from: '[email protected]'
+                      currentBuild.result = 'ABORTED'
+                      error('Abort scheduled build due to no changes')
+                    }
+                  }
             }
 		}
 	  stage('Aggregator maven build'){

cje-production/mbscripts/mb110_tagBuildInputs.sh

@@ -46,6 +46,15 @@ fi
 
 pushd $CJE_ROOT/$AGG_DIR
 
+if $ABORT_IF_NO_CHANGES;then
+  listChangesInRepo="git diff ${lastTag}..HEAD --name-only"
+  if [[ -z $(${listChangesInRepo}) && -z $(git submodule --quiet foreach ${listChangesInRepo}) ]];then
+    echo "No changes in git repository since : ${lastTag}"
+    touch "${WORKSPACE}/noChanges"
+    exit 0
+  fi
+fi
+
 # git tagging
 if [ "${BUILD_TYPE}" == "I" ]
 then