gitlab-ci: publish buildserver image to Docker Registry

.gitlab-ci.yml

@@ -529,3 +529,25 @@ pages:
   needs: ["Build documentation"]
   rules:
     - if: '$CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH'  # only publish pages on default (master) branch
+
+
+docker:
+  dependencies:
+    - fdroid build
+  only:
+    changes:
+      - .gitlab-ci.yml
+      - makebuildserver
+      - buildserver/*
+  image: docker:git
+  services:
+    - docker:dind
+  variables:
+    TEST_IMAGE: registry.gitlab.com/$CI_PROJECT_NAMESPACE/${CI_PROJECT_NAME}:$CI_BUILD_REF_NAME
+    RELEASE_IMAGE: registry.gitlab.com/$CI_PROJECT_NAMESPACE/${CI_PROJECT_NAME}:buildserver
+  script:
+    - cd buildserver
+    - docker build -t $TEST_IMAGE --build-arg GIT_REV_PARSE_HEAD=$(git rev-parse HEAD) .
+    - docker tag $TEST_IMAGE $RELEASE_IMAGE
+    - echo $CI_BUILD_TOKEN | docker login -u gitlab-ci-token --password-stdin registry.gitlab.com
+    - docker push $RELEASE_IMAGE