Add dockerfile and build docker image in CI

.gitlab-ci.yml

@@ -2,6 +2,7 @@ image: node:lts-jessie
 
 stages:
   - test
+  - build
 
 audit:
   stage: test
@@ -30,4 +31,20 @@ lint-client:
     - eslint . 
   only:
     - merge_requests
-    - master
+    - master
+
+build-image:
+  stage: build
+  image: docker:stable
+  services:
+    - docker:dind
+  before_script:
+    - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
+  variables:
+    IMAGE_TAG: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
+  script:
+    - docker build -t $IMAGE_TAG .
+    - docker push $IMAGE_TAG
+  only:
+    - master
+    - tags

Dockerfile

@@ -0,0 +1,20 @@
+# Base image on Node.js 10.x LTS (dubnium)
+FROM node:10
+
+# Create app directory
+WORKDIR /usr/src/isleward
+
+# Bundle app source
+COPY . .
+
+# Change directory to src/server/
+WORKDIR /usr/src/isleward/src/server/
+
+# Install npm modules specified in package.json
+RUN npm install --only-production
+
+# Expose container's port 4000
+EXPOSE 4000
+
+# Launch Isleward server
+CMD ["node", "--expose-gc", "index.js"]