push only with tag

.gitlab-ci.yml

 
 stages:
   - build
+  - deploy
+  - cleanup
 
 variables:
   imageversion: "2.2"
   rootfsurl: "https://data.perryflynn.de/rootfs-stretch-20181211.tar.gz"
   rootfssha256sum: "f2b79ce732c0fd47a65bda6c51c9bef7d9d9037bd483037edafab722843b50cd"
+  pushtag: "${CI_REGISTRY}/${CI_PROJECT_NAMESPACE}/${CI_PROJECT_NAME}:${imageversion}"
 
 before_script:
   - 'chmod a+x build.sh'
 
 build:
   stage: build
-  only:
-    - tags
-    - triggers
-  variables:
-    pushtag: "${CI_REGISTRY}/${CI_PROJECT_NAMESPACE}/${CI_PROJECT_NAME}:${imageversion}"
   script:
     - 'curl "${rootfsurl}" > rootfs.tar.gz'
     - 'echo "${rootfssha256sum} rootfs.tar.gz" | sha256sum -c &> /dev/null || exit 98'
     - "./build.sh --rootfstarfile rootfs.tar.gz --imagename ${pushtag}"
     - 'rm -f rootfs.tar.gz'
+
+deploy:
+  stage: deploy
+  only:
+    - tags
+    - triggers
+  script:
     - "docker login -u gitlab-ci-token -p $CI_JOB_TOKEN ${CI_REGISTRY}"
     - "docker push ${pushtag}"
     - "docker logout ${CI_REGISTRY}"
-    - "docker image rm ${pushtag}"
+
+cleanup:
+  stage: cleanup
+  script:
+    - "docker image prune -a -f"