Merge branch 'ci' into 'master'

add ci pipeline

See merge request !1

.gitlab-ci.yml

+stages:
+  - test
+  - build
+
+run tests:
+  image: dlang2/dmd-ubuntu:2.083.1
+  script:
+    - dub test
+
+auto build and push:
+  image: docker:stable
+  before_script:
+    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+  stage: build
+  script:
+    - docker pull $CI_REGISTRY_IMAGE:latest || true
+    - docker build --cache-from $CI_REGISTRY_IMAGE:latest -t $CI_REGISTRY_IMAGE:latest -t $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG .
+    - docker push $CI_REGISTRY_IMAGE:latest $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
+  only:
+    - master
+  tags:
+    - build
+
+build and push:
+  image: docker:stable
+  before_script:
+    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+  stage: build
+  script:
+    - docker pull $CI_REGISTRY_IMAGE:latest || true
+    - docker build --cache-from $CI_REGISTRY_IMAGE:latest -t $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG .
+    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
+  except:
+    - master
+  when: manual
+  tags:
+    - build

Dockerfile

+FROM dlang2/dmd-ubuntu:2.083.1 as build
+WORKDIR /dlang/d-webservice-example
+COPY . .
+
+RUN dub build --build=release
+
+FROM ubuntu:17.10
+EXPOSE 8080
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN set -ex && \
+    apt-get update && \
+    apt-get install --no-install-recommends -y \
+    ca-certificates \
+    libssl1.0.0
+
+COPY --from=build /dlang/d-webservice-example/d-webservice-example /dlang/d-webservice-example/d-webservice-example
+
+RUN useradd --user-group --create-home --shell /bin/false app && \
+    chown -R app:app /dlang/d-webservice-example
+USER app
+
+CMD ["/dlang/d-webservice-example/d-webservice-example]