Merge branch '372-allow-empty-kaniko_build_imagename-var' into 'master'

Resolve "Allow empty KANIKO_BUILD_IMAGENAME var"

Closes #372

See merge request openappstack/openappstack!133

.gitlab/ci_templates/kaniko.yml

 # Optional environment variables:
-# - KANIKO_BUILD_IMAGENAME: Build/target image image
+#
+# - KANIKO_BUILD_IMAGENAME: Build/target image name.
+#   If empty, image URL will be the root of the gitlab project path, i.e.
+#     `open.greenhost.net:4567/GROUP/PROJECT:TAG
+#   Is set, images will be named like
+#     `open.greenhost.net:4567/GROUP/PROJECT/KANIKO_BUILD_IMAGENAME:TAG
+#
 # - KANIKO_CONTEXT: The subdir which holds the Dockerfile, leave unset if
 #                   the Dockerfile is located at root level of the project.
 .kaniko_build:
@@ -11,4 +17,5 @@
     entrypoint: [""]
   script:
     - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
-    - /kaniko/executor --context ${CI_PROJECT_DIR}/${KANIKO_CONTEXT:-.} --dockerfile ${CI_PROJECT_DIR}/${KANIKO_CONTEXT:-.}/Dockerfile --destination $CI_REGISTRY_IMAGE/${KANIKO_BUILD_IMAGENAME/#//}:${CI_COMMIT_REF_NAME}
+    - if [ -n "${KANIKO_BUILD_IMAGENAME}" ]; then  export IMAGENAME="/${KANIKO_BUILD_IMAGENAME}"; fi
+    - /kaniko/executor --context ${CI_PROJECT_DIR}/${KANIKO_CONTEXT:-.} --dockerfile ${CI_PROJECT_DIR}/${KANIKO_CONTEXT:-.}/Dockerfile --destination ${CI_REGISTRY_IMAGE}${IMAGENAME}:${CI_COMMIT_REF_NAME}