OZG-533 add slack notification

Jenkinsfile

@@ -7,6 +7,10 @@ pipeline {
         }
     }
 
+    environment {
+        BLUE_OCEAN_URL = "https://jenkins.ozg-sh.de/blue/organizations/jenkins/goofy/detail/${env.BRANCH_NAME}/${env.BUILD_NUMBER}/pipeline"
+    }
+
     options {
         timeout(time: 1, unit: 'HOURS')
         disableConcurrentBuilds()
@@ -155,6 +159,9 @@ pipeline {
             }
             
             steps {
+                script {
+                    FAILED_STAGE = env.STAGE_NAME
+                }
                 container("docker") {
                     script {
                         withCredentials([usernamePassword(credentialsId: 'jenkins-docker-login', usernameVariable: 'USER', passwordVariable: 'PASSWORD')]) {
@@ -189,4 +196,13 @@ pipeline {
             }
         }
     }
+    post {
+        failure {
+            script {
+                if (env.BRANCH_NAME == 'master') {
+                    slackSend(color: "danger", message: "Goofy: Build Failed. Stage: ${FAILED_STAGE} Build-ID: <${BLUE_OCEAN_URL}|${env.BUILD_NUMBER}>")
+                }
+            }
+        }
+    }
 }
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