GitLab CI: build a docker image

.gitlab-ci.yml

@@ -142,3 +142,16 @@ pages:
   only:
     refs:
       - develop
+
+docker:
+  image: docker:20.10.17
+  services:
+    - docker:20.10.17-dind       
+  # https://medium.com/devops-with-valentine/how-to-build-a-docker-image-and-push-it-to-the-gitlab-container-registry-from-a-gitlab-ci-pipeline-acac0d1f26df
+  script:
+    - echo $CI_REGISTRY_PASSWORD | docker login -u $CI_REGISTRY_USER $CI_REGISTRY --password-stdin
+    - docker build -t $CI_REGISTRY_IMAGE .
+    - docker push $CI_REGISTRY_IMAGE
+  # only:
+  #   refs:
+  #     - develop