Improve docker-build-to-jfrog pipeline

Build image not for each tag, using one pre-builded image for tagging

Change-Id: Ic11cf2f35c03d41ab36c94d609a0fd569789946d
diff --git a/docker-build-to-jfrog.groovy b/docker-build-to-jfrog.groovy
index 2973621..83fe66b 100644
--- a/docker-build-to-jfrog.groovy
+++ b/docker-build-to-jfrog.groovy
@@ -36,9 +36,13 @@
       ])
     }
     stage("build image"){
+      containerId = sh(
+        script: "docker build -f ${DOCKERFILE_PATH}/Dockerfile -q --rm . | awk -F':' '{print \$2}'",
+        returnStdout: true
+      ).trim().take(12)
       imageTagsList << "${GERRIT_CHANGE_NUMBER}_${GERRIT_PATCHSET_NUMBER}"
       for (imageTag in imageTagsList) {
-        sh "docker build -f ${DOCKERFILE_PATH}/Dockerfile -t ${dockerRepository}/${projectNamespace}/${projectModule}:${imageTag} --rm ."
+        sh "docker tag ${containerId} ${dockerRepository}/${projectNamespace}/${projectModule}:${imageTag}"
       }
     }
     stage("publish image"){