Add .gitlab-ci.yml

.gitlab-ci.yml

+image: docker:19.03.11
+services:
+  - docker:19.03.11-dind
+
+stages:
+  - build
+  - test
+  - release
+  - deploy
+
+variables:
+  # Use TLS https://docs.gitlab.com/ee/ci/docker/using_docker_build.html#tls-enabled
+  DOCKER_HOST: tcp://docker:2376
+  DOCKER_TLS_CERTDIR: "/certs"
+  CONTAINER_TEST_IMAGE: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
+  CONTAINER_RELEASE_IMAGE: $CI_REGISTRY_IMAGE:latest
+
+before_script:
+  - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+
+build:
+  stage: build
+  script:
+    - docker build --pull -t $CONTAINER_TEST_IMAGE .
+    - docker push $CONTAINER_TEST_IMAGE
+
+test1:
+  stage: test
+  script:
+    - docker pull $CONTAINER_TEST_IMAGE
+    - docker run $CONTAINER_TEST_IMAGE /script/to/run/tests
+
+test2:
+  stage: test
+  script:
+    - docker pull $CONTAINER_TEST_IMAGE
+    - docker run $CONTAINER_TEST_IMAGE /script/to/run/another/test
+
+release-image:
+  stage: release
+  script:
+    - docker pull $CONTAINER_TEST_IMAGE
+    - docker tag $CONTAINER_TEST_IMAGE $CONTAINER_RELEASE_IMAGE
+    - docker push $CONTAINER_RELEASE_IMAGE
+  only:
+    - master
+
+deploy:
+  stage: deploy
+  script:
+    - ./deploy.sh
+  only:
+    - master
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