Fix authentication to the image registry

.gitlab-ci.yml

@@ -46,13 +46,9 @@ build:image:
     name: gcr.io/kaniko-project/executor:v1.3.0-debug
     entrypoint: [""]
   variables:
-    REGISTRY_SERVER: $CSUI_REGISTRY_SERVER
-    REGISTRY_USERNAME: $CSUI_REGISTRY_USERNAME
-    REGISTRY_PASSWORD: $CSUI_REGISTRY_PASSWORD
     IMAGE_TAG: latest
   before_script:
-    - export REGISTRY_AUTH=$(printf $REGISTRY_USERNAME:$REGISTRY_PASSWORD | base64)
-    - printf "{\"auths\":{\"$REGISTRY_SERVER\":{\"auth\":\"$REGISTRY_AUTH\"}}}" > /kaniko/.docker/config.json
+    - mv ${CSUI_REGISTRY_AUTH_FILE} /kaniko/.docker/config.json
   script:
     - /kaniko/executor
       --cache
@@ -65,5 +61,4 @@ build:image:
       --single-snapshot
       --use-new-run
   after_script:
-    - unset REGISTRY_AUTH
     - rm /kaniko/.docker/config.json