Dockerfile
# base image
FROM node:12.2.0-alpine
# set working directory
WORKDIR /app
# add `/app/node_modules/.bin` to $PATH
ENV PATH /app/node_modules/.bin:$PATH
# install and cache app dependencies
COPY package.json /app/package.json
RUN yarn
RUN yarn add react-scripts@3.0.1 -g --silent
# start app
CMD ["yarn", "start"]