react-express-mysql: split backend code

Signed-off-by: Jérémie Drouet <jeremie.drouet@gmail.com>

react-express-mysql/backend/Dockerfile

@@ -1,36 +1,31 @@
 # if you're doing anything beyond your local machine, please pin this to a specific version at https://hub.docker.com/_/node/
-FROM node:10
-
-RUN mkdir -p /opt/app
+FROM node:lts
 
 # set our node environment, either development or production
 # defaults to production, compose overrides this to development on build and run
 ARG NODE_ENV=production
 ENV NODE_ENV $NODE_ENV
 
+WORKDIR /code
+
 # default to port 80 for node, and 9229 and 9230 (tests) for debug
 ARG PORT=80
 ENV PORT $PORT
 EXPOSE $PORT 9229 9230
 
-# you'll likely want the latest npm, reguardless of node version, for speed and fixes
-RUN npm i npm@latest -g
-
-# install dependencies first, in a different location for easier app bind mounting for local development
-WORKDIR /opt
-COPY package.json package-lock.json* ./
-RUN npm install && npm cache clean --force
-ENV PATH /opt/node_modules/.bin:$PATH
+COPY package.json /code/package.json
+COPY package-lock.json /code/package-lock.json
+RUN npm ci && npm cache clean --force
 
 # check every 30s to ensure this service returns HTTP 200
-HEALTHCHECK --interval=30s CMD node healthcheck.js
+HEALTHCHECK --interval=30s \
+  CMD node healthcheck.js
 
 # copy in our source code last, as it changes the most
-WORKDIR /opt/app
-COPY . /opt/app
+COPY . /code
 
 # if you want to use npm start instead, then use `docker run --init in production`
 # so that signals are passed properly. Note the code in index.js is needed to catch Docker signals
 # using node here is still more graceful stopping then npm with --init afaik
 # I still can't come up with a good production way to run with npm and graceful shutdown
-CMD [ "node", "index.js" ]
+CMD [ "node", "src/index.js" ]