Sample node.js Dockerfile

Dockerfile

##################################
# Dev dependencies stage, only prepares node_modules, that are later reused
##################################

FROM node:14-slim as devdependencies
USER node
WORKDIR /app
COPY --chown=node:node package.json yarn.lock ./

# Use docker mount cache, with locked sharing to avoid concurrency issues.
# Sets uid & gid of the node user for correct permissions
RUN --mount=type=cache,target=/home/node/.cache/yarn,uid=1000,gid=1000,sharing=locked yarn install --ignore-optional

##################################
# Build stage, creates a /app/dist directory with the compiled app.
# We don't use this stage as production, because it needs dev dependencies for the build, but we don't
# need these to actually run the compiled app
##################################

FROM node:14-slim as build

USER node
WORKDIR /app

ARG NODE_ENV=production
ENV NODE_ENV $NODE_ENV

COPY --chown=node:node --from=devdependencies /app .
COPY --chown=node:node . .

RUN yarn run build && ls -lah

##################################
# Production stage
# - installs only production dependencies (no devDependencies)
# - copies the dist directory from build stage
# - sets default NODE_ENV to production
# - exposes $PORT (3000)
# - sets propper PATH
##################################

FROM node:14-slim as production

ARG NODE_ENV=production
ENV NODE_ENV $NODE_ENV

ARG PORT=3000
ENV PORT $PORT
EXPOSE $PORT

USER node
WORKDIR /app

COPY --chown=node:node package.json yarn.lock ./

# Use docker mount cache, with locked sharing to avoid concurrency issues.
# Sets uid & gid of the node user for correct permissions
RUN --mount=type=cache,target=/home/node/.cache/yarn,uid=1000,gid=1000,sharing=locked yarn install --ignore-optional && (rm -rf /tmp/* || true)

ENV PATH /app/node_modules/.bin:$PATH

COPY --chown=node:node --from=build /app/dist ./

CMD [ "node", "src/main.js" ]

##################################
# Development stage
# This is not used at the moment, since the node_modules synchronization with host is complicated.
# Left here for future reference if we decide to run the app in docker during development.
##################################

FROM node:14-slim as development

USER node
WORKDIR /app

ARG NODE_ENV=development
ENV NODE_ENV $NODE_ENV

# default to port 3000 for node, and 9229 and 9230 (tests) for debug
ARG PORT=3000
ENV PORT $PORT
EXPOSE $PORT 9229 9230

ENV PATH /app/node_modules/.bin:$PATH

COPY --chown=node:node --from=devdependencies /app .
COPY --chown=node:node . .

CMD ["yarn", "start:dev"]