yarn-plugin-fetch

Optimized yarn workflow for docker build. Don't re-download all your dependencies on each package.json change.

Implementation of pnpm fetch for yarn berry with additional features:

workspace focus support
custom install command

It work's by expanding your yarn.lock into package.json file(s) and structured workspaces.

requirements:

yarn berry (>= 2)

migration to yarn berry

run yarn set version berry in your repository
https://yarnpkg.com/getting-started/qa#which-files-should-be-gitignored
to ensure retrocompatibility, put in your .yarnrc.yml: nodeLinker: pnpm (recommended, all advantages of pnpm symlink method) or nodeLinker: node-modules (better compatibility)

getting started

yarn plugin import https://raw.githubusercontent.com/devthejo/yarn-plugin-fetch/master/bundles/@yarnpkg/plugin-fetch.js

Docker implementation

standalone repository

Dockerfile

COPY yarn.lock .yarnrc.yml ./
COPY .yarn .yarn
RUN yarn fetch --immutable

COPY . .

RUN yarn postinstall # if you have postinstall script in your package.json
RUN yarn build # and/or other build commands

production optimization

This is specific to yarn berry, not directly related to this plugin, but this documentation attempt to be a complete migration guide from yarn classic (v1) to yarn berry (v2+).

Yarn berry need workspace-tools plugin to support --production (This plugin is included by default starting from Yarn 4).

You can install it with this simple command:

yarn plugin import workspace-tools

Then you can add this line of previous example:

RUN yarn workspaces focus --production

And if you have postinstall script in your package.json that needs dev dependencies, you can replace by this command instead:

RUN yarn fetch-tools production

And if you are really anal you can do:

RUN yarn fetch-tools production && yarn cache clean

Note: this optimization will make sense in case you make a multistage Dockerfile and copy node_modules in the final stage, eg:

FROM node as build
COPY yarn.lock .yarnrc.yml ./
COPY .yarn .yarn
RUN yarn fetch --immutable

COPY . .

RUN yarn postinstall # if you have postinstall script in your package.json
RUN yarn build # and/or other build commands
RUN yarn fetch-tools production

FROM node as final
COPY --from=build /app/node_modules /app/node_modules

monorepo

You need the workspace-tools plugin to be installed to implement this example (This plugin is included by default starting from Yarn 4). You can install it with yarn plugin import workspace-tools.

package/mypackage/Dockerfile

COPY yarn.lock .yarnrc.yml .
COPY .yarn .yarn
RUN yarn fetch --workspace mypackage

COPY package/mypackage .

# COPY package/my-package-dep1 . # if you have one or many workspace dependencies
RUN yarn workspaces foreach -t run postinstall # if you have postinstall scripts in your package.json file(s)
RUN yarn workspace mypackage build # and/or other build commands

RUN yarn workspace mypackage focus --production

extra commands (fetch-tools)

production

This need workspace-tools plugin to support --production (This plugin is included by default starting from Yarn 4). You can install it with yarn plugin import workspace-tools.

This command will clean the dev dependencies (generally implemented after build):

yarn fetch-tools production

it's equivalent to

yarn fetch-tools disable-postinstall
yarn workspaces focus --production
yarn fetch-tools enable-postinstall

all extra arguments are transmitted as argument to yarn workspaces focus --production command.

expand-lock

If you don't want to install dependencies but want to expand the yarn.lock to package.json only, you can run:

yarn fetch-tools expand-lock

postinstall

this is renaming the scripts postinstall key in package.json to _postinstall

yarn fetch-tools disable-postinstall

and this revert it

yarn fetch-tools enable-postinstall

further documentation

this plugin is based on the work of Rohit Gohri on the great package yarn-lock-to-package-json

https://github.com/rohit-gohri/yarn-lock-to-package-json/

devthejo / yarn-plugin-fetch