Deploy react app to heroku using Node 8.4 official image

.dockerignore

# Items that don't need to be in a Docker image.
# Anything not used by the build system should go here.
Dockerfile
.dockerignore
.gitignore
README.md
yarn.lock

# Artifacts that will be built during image creation.
# This should contain all files created during `npm run build`.
.git
dist
node_modules

Dockerfile

FROM node:8.4.0

# Override the base log level (info).
ENV NPM_CONFIG_LOGLEVEL warn

# Install `serve`.
RUN npm install -g serve

# Install all dependencies of the current project.
COPY package.json package.json
RUN npm install

# Copy all local files into the image.
COPY . .

# Build for production.
RUN npm run build

# serve static files in dist folder
CMD serve -p $PORT -s dist

For an explanation, please check the article.