Yarn cache compatible Dockerfile

README.md

Yarn Dockerfile

An yarn cache compatible Dockerfile, for building node.js images faster.

Usage

Clone this gist into your project root, and add it to your source control. Change the image service-name:latest tag to your project name in the Dockerfile and build.sh files. Then, always build your image using the build.sh script.

$ chmod +x ./build.sh
$ ./build.sh

build.sh

#!/bin/bash

if [ ! -f .yarn-cache.tgz ]; then
  echo "+ build: Init empty .yarn-cache.tgz"
  tar cvzf .yarn-cache.tgz --files-from /dev/null
fi

docker build -t service-name:latest .

docker run \
  --rm \
  --entrypoint cat \
  service-name:latest \
  /tmp/yarn.lock > /tmp/yarn.lock

if ! diff -q yarn.lock /tmp/yarn.lock > /dev/null  2>&1; then
  echo "+ build: Saving Yarn cache"

  docker run \
    --rm \
    --entrypoint tar \
    service-name:latest \
    czf - /root/.yarn-cache/ > .yarn-cache.tgz

  echo "+ build: Saving yarn.lock"

  cp /tmp/yarn.lock yarn.lock
fi

Dockerfile

FROM alpine

RUN apk add --update --no-cache nodejs
RUN npm i -g yarn

ADD package.json yarn.lock /tmp/
ADD .yarn-cache.tgz /

RUN cd /tmp && yarn
RUN mkdir -p /service && cd /service && ln -s /tmp/node_modules

COPY . /service
WORKDIR /service

ENV FORCE_COLOR=1

ENTRYPOINT ["npm"]
CMD ["start"]

@etgrieco Ah, okay. I am developing a Next.js app, and its dependency installation is quite annoying. Without such a "trick", when I change something in package.json, it takes over 150 + seconds just for the yarn install step when a rebuild the Docker Image. So, any trick/optimization technique would be greatly appreciated!