separated purge&build image jobs

.gitlab-ci.yml

 stages:
-  - push-image
+  - purge
+  - build
   - rf-test
   - push-results
 
@@ -7,22 +8,27 @@ docker-push:
   image: docker
   services:
     - docker:dind
-  stage: push-image
+  stage: purge
   tags: ['docker']
   only:
     - testing
-  before_script:
-    - printf "REACT_APP_URL=%s\n" "$REACT_APP_URL" > .env
-    - echo "$DOCKERHUB_PASS" | docker login -u "$DOCKERHUB_USER" --password-stdin
+  script:
     - docker stop front
     - docker rm front
   allow_failure: true
+
+docker-build:
+  image: docker
+  services:
+    - docker:dind
+  stage: build
+  tags: ['docker']
+  only:
+    - testing
   script:
+    - printf "REACT_APP_URL=%s\n" "$REACT_APP_URL" > .env
     - docker build -t overflow2019/frontend:test .
-    - docker push overflow2019/frontend
     - docker run --name front -p 8080:3000 -d overflow2019/frontend:test
-  after_script:
-    - docker logout
 
 rf-test:
   image: gitlab.labranet.jamk.fi:4567/wimma-lab-2019/mysticons/devsecops/robot