Node and docker - how to handle babel or typescript build?

The modern recommendation for this sort of thing (as of Docker 17.05) is to use a multi-stage build. This way you can use all your dev/build dependencies in the one Dockerfile but have the end result optimised and free of unnecessary code.

I'm not so familiar with typescript, but here's an example implementation using yarn and babel. Using this Dockerfile, we can build a development image (with docker build --target development .) for running nodemon, tests etc locally; but with a straight docker build . we get a lean, optimised production image, which runs the app with pm2.

# common base image for development and production
FROM node:10.11.0-alpine AS base
WORKDIR /app


# dev image contains everything needed for testing, development and building
FROM base AS development
COPY package.json yarn.lock ./

# first set aside prod dependencies so we can copy in to the prod image
RUN yarn install --pure-lockfile --production
RUN cp -R node_modules /tmp/node_modules

# install all dependencies and add source code
RUN yarn install --pure-lockfile
COPY . .


# builder runs unit tests and linter, then builds production code 
FROM development as builder
RUN yarn lint
RUN yarn test:unit --colors
RUN yarn babel ./src --out-dir ./dist --copy-files


# release includes bare minimum required to run the app, copied from builder
FROM base AS release
COPY --from=builder /tmp/node_modules ./node_modules
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/package.json ./
CMD ["yarn", "pm2-runtime", "dist/index.js"]

I personally prefer to just remove dev dependencies after running babel during build:

FROM node:7

# Create app directory
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app

# Install app dependencies
COPY package.json /usr/src/app/
RUN npm install

# Copy app source
COPY src /usr/src/app/src

# Compile app sources
RUN npm run compile

# Remove dev dependencies
RUN npm prune --production

# Expose port and CMD
EXPOSE 8080
CMD [ "npm", "start" ]

One possible solution is to wrap your build procedure in a special docker image. It is often referred as Builder image. It should contain all your build dependencies: nodejs, npm, gulp, babel, tsc and etc. It encapsulates all your build process, removing the need to install these tools on the host.

First you run the builder image, mounting the source code directory as a volume. The same or a separate volume can be used as output directory. The first image takes your code and runs all build commands.

As a first step you take your built code and pack it into production docker image as you do now.

Here is an example of docker builder image for TypeScript: https://hub.docker.com/r/sandrokeil/typescript/

It is ok to have the same docker builder for several projects as it is typically designed to be general purpose wrapper around some common tools. But it is ok to build your own that describes more complicated procedure.

The good thing about builder image is that your host environment remains unpolluted and you are free to try newer versions of compiler/different tools/change order/do tasks in parallel just by modifing Dockerfile of your builder image. And at any time you can rollback your experiment with build procedure.