Enhancement: Improve Dockerfile for cached layer handling

virtuman commented 6 months ago

What features would you like to see added?

Docker takes too long, couple simple manipulations will drastically improve build times and utilize cached layers, to avoid entire image rebuild on each run. You can see screenshots below, to notice build time differences

More details

something like this would result in a quicker build, given that you use runner that has docker cache, or pull :latest and use as cache. And minimize number of RUN commands, so that it doesn't persist layer after each command

here're the differences:

[*] first complete steps that are more permanent and don't need to be redone every time (like apk and npm -g)
[*] switch to user before copying files, this will automatically move files under that user
[*] WORKDIR will actually auto-create a folder with the set user already
[*] unfortunately requires tiny hardcode with paths, so we copy only changed code that requires re-compile before npm install
[*] then run NPM install (otherwise, it runs npm install and download tens of mbs on every codebase change)
copy all changed code
compile app

all steps that i marked, will re-use cached layers, and only app build will re-run on every rebuild of the app

this way, image build will go to seconds, if you use runners that have perstitent docker or use --pull in docker build command, to re-use cached layers (that will add few extra seconds to pull last built image as cache from docker registry)

Below is a working version of Dockerfile that I use it myself

# Base node image
FROM node:18-alpine AS node

RUN apk add --no-cache g++ make py3-pip curl && \
        npm config set fetch-retry-maxtimeout 300000 && \
        npm install -g node-gyp npm

USER node

WORKDIR /app

# Copy package.json and package-lock.json (if available)
COPY --chown=node:node package.json package-lock.json* ./
COPY --chown=node:node config config/
COPY --chown=node:node api/package.json api/
COPY --chown=node:node client/package.json client/
COPY --chown=node:node packages/data-provider/package.json packages/data-provider/

# Install dependencies
RUN npm install --no-audit
# Allow mounting of these files, which have no default
# values.
RUN touch .env

# Copy the rest of the application code
COPY --chown=node:node . .

# React client build
ENV NODE_OPTIONS="--max-old-space-size=2048"
RUN npm run frontend

# Node API setup
EXPOSE 3080
ENV HOST=0.0.0.0
CMD ["npm", "run", "backend"]

# Optional: for client with nginx routing
# FROM nginx:stable-alpine AS nginx-client
# WORKDIR /usr/share/nginx/html
# COPY --from=node /app/client/dist /usr/share/nginx/html
# COPY client/nginx.conf /etc/nginx/conf.d/default.conf
# EXPOSE 80
# ENTRYPOINT ["nginx", "-g", "daemon off;"]