message: Use yarn in Dockerfile
diff: @@ -6,8 +6,8 @@ RUN mkdir -p /usr/src/app
  WORKDIR /usr/src/app
  # Install app dependencies
  -COPY package.json /usr/src/app/
  -RUN npm install --quiet
  +COPY package.json yarn.lock /usr/src/app/
  +RUN yarn install --frozen-lockfile --prefer-offline
  # Bundle app source
  COPY . /usr/src/app
  