Fix backend dockerfile

[zetos]

The build script is no longer working.

Some needed changes:

• Update node version on the Dockerfile.
• The command RUN npm install puppeteer will install the puppeteer 3.x.x with can have breaking changes.

---

This is a suggestion for a Dockerfile that worked for me. I changes the node image to use Alpine, and added the "puppeteer": "^2.0.0" dependency on the package.json.

I also changed the following lines on the server.js from:

    code = code.replace(/\.launch\([\w\W]*?\)/g,
        ".launch({args: ['--no-sandbox', '--disable-dev-shm-usage']})");

to:

    code = code.replace(/\.launch\([\w\W]*?\)/g,
        ".launch({executablePath: '/usr/bin/chromium-browser', args: ['--disable-dev-shm-usage']})");

Dockerfile:

FROM node:alpine

# Tell Puppeteer to skip installing Chrome. We'll be using the installed package.
ENV PUPPETEER_SKIP_CHROMIUM_DOWNLOAD true

# Installs latest Chromium (79) package.
RUN apk add --no-cache \
      chromium \
      nss \
      freetype \
      freetype-dev \
      harfbuzz \
      ca-certificates \
      ttf-freefont

ADD https://github.com/Yelp/dumb-init/releases/download/v1.2.1/dumb-init_1.2.1_amd64 /usr/local/bin/dumb-init
RUN chmod +x /usr/local/bin/dumb-init

WORKDIR /usr/src/app

COPY . .
COPY package*.json ./

# Install deps for server.
RUN npm install --only=production

# building the image.
ARG CACHEBUST=1

# Add pptr user.
RUN addgroup -S pptruser && adduser -S -G pptruser pptruser \
    && mkdir -p /home/pptruser/Downloads \
    && chown -R pptruser:pptruser /home/pptruser \
    && chown -R pptruser:pptruser ../app

# Run user as non privileged.
USER pptruser

EXPOSE 8080

ENTRYPOINT ["dumb-init", "--"]
CMD ["node", "server.js"]