Update CONTRIBUTING, add Docker to Pipeline

.circleci/config.yml

@@ -50,9 +50,45 @@ jobs:
           command: |
             yarn coverage
 
+  build:
+    docker:
+      - image: docker:latest
+    steps:
+      - checkout
+      - setup_remote_docker:
+          version: 20.10.7
+      - run:
+          name: Load Docker image layer cache
+          command: |
+            set +o pipefail
+            docker load -i /caches/app.tar | true
+      - run:
+          name: Build application Docker image
+          command: |
+            docker build --cache-from=app -t app .
+      - run:
+          name: Save Docker image layer cache
+          command: |
+            mkdir -p /caches
+            docker save -o /caches/app.tar app
+      - save_cache:
+          key: v1-{{ .Branch }}-{{ epoch }}
+          paths:
+            - /caches/app.tar
+      - deploy:
+          name: Push application Docker image
+          command: |
+            docker login --username ${DOCKER_USER} --password ${DOCKER_PASSWORD}
+            docker tag app phntxx/dashboard:latest
+            docker push phntxx/dashboard:latest
+
 workflows:
   version: 2
   dashboard:
     jobs:
       - style
       - dashboard
+      - build:
+          requires:
+            - style
+            - dashboard