fix image tag (for semver)

scripts/build_image.sh

@@ -37,17 +37,18 @@ fi
 echo -e "Existing images in registry"
 bx cr images
 
-# Minting image tag using format: BRANCH-BUILD_NUMBER-COMMIT_ID-TIMESTAMP
-# e.g. master-3-50da6912-20181123114435
+# Minting image tag using format: BUILD_NUMBER--BRANCH-COMMIT_ID-TIMESTAMP
+# e.g. 3-master-50da6912-20181123114435
+# (use build number as first segment to allow image tag as a patch release name according to semantic versioning)
 
 TIMESTAMP=$( date -u "+%Y%m%d%H%M%S")
 IMAGE_TAG=${TIMESTAMP}
 if [ ! -z "${GIT_COMMIT}" ]; then
   GIT_COMMIT_SHORT=$( echo ${GIT_COMMIT} | head -c 8 ) 
   IMAGE_TAG=${GIT_COMMIT_SHORT}-${IMAGE_TAG}
 fi
-IMAGE_TAG=${BUILD_NUMBER}-${IMAGE_TAG}
 if [ ! -z "${GIT_BRANCH}" ]; then IMAGE_TAG=${GIT_BRANCH}-${IMAGE_TAG} ; fi
+IMAGE_TAG=${BUILD_NUMBER}-${IMAGE_TAG}
 echo "=========================================================="
 echo -e "BUILDING CONTAINER IMAGE: ${IMAGE_NAME}:${IMAGE_TAG}"
 if [ -z "${DOCKER_ROOT}" ]; then DOCKER_ROOT=. ; fi