Refactor out authentication job from build job

.gitlab-ci.yml

@@ -1,25 +1,31 @@
 stages:
+  - auth
   - build
   - publish
   - deploy
 
+auth-job:
+  stage: auth
+  image: docker:stable
+  script:
+    - docker login --username "$REGISTRY_USER" --password "$REGISTRY_PASSWORD" "$REGISTRY_BASE_URL"
+  artifacts:
+    paths:
+      - ~/.docker/
+
 build-job:
   stage: build
   image: docker:stable
   tags:
     - docker
   script:
-    - docker login --username "$REGISTRY_USER" --password "$REGISTRY_PASSWORD" "$REGISTRY_BASE_URL"
     - docker -H unix:///var/run/docker.sock image build -t "$REGISTRY_BASE_URL/$DOCKER_IMAGE_NAME:$CI_COMMIT_SHORT_SHA" ./
-  artifacts:
-    paths:
-      - ~/.docker/
 
 publish-job:
   stage: publish
   image: docker:stable
   dependencies:
-    - build-job
+    - auth-job
   tags:
     - docker
   script:
@@ -30,7 +36,7 @@ deploy-job:
   when: manual
   image: google/cloud-sdk
   dependencies:
-    - build-job
+    - auth-job
   script:
     - export KUBECONFIG="$KUBE_AUTH"
     - cp "$ENV_PRODUCTION" "./build/.env.production"