Add GitLab CI integration

.gitlab-ci.yml

@@ -0,0 +1,32 @@
+image: docker:20
+
+stages:
+  - build
+  - tag
+
+before_script:
+  - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+
+build:
+  stage: build
+  only:
+    - main
+  services:
+    - docker:dind
+  script:
+    - docker build --quiet --tag=${CI_REGISTRY_IMAGE}:latest
+    - docker push ${CI_REGISTRY_IMAGE}:latest
+
+tag:
+  stage: tag
+  only:
+    - tags
+  variables:
+    # Don't clone the project source-- we're just tagging a docker image:
+    GIT_STRATEGY: none
+  services:
+    - docker:dind
+  script:
+    - docker pull ${CI_REGISTRY_IMAGE}:latest
+    - docker tag ${CI_REGISTRY_IMAGE}:latest ${CI_REGISTRY_IMAGE}:${CI_COMMIT_REF_NAME}
+    - docker push ${CI_REGISTRY_IMAGE}:${CI_COMMIT_REF_NAME}