pnpm fetch
Fetch packages from a lockfile into virtual store, package manifest is ignored.
Usage scenario
This command is specifically designed to boost building a docker image.
You may have read the official guide to writing a Dockerfile for a Node.js app, if you didn't read it yet, you may want to read it first.
From that guide, we learn to write an optimized Dockerfile for projects using pnpm, which shall look like
FROM node:14
RUN curl -f https://get.pnpm.io/v6.16.js | node - add --global pnpm
# Files required by pnpm install
COPY .npmrc package.json pnpm-lock.yaml .pnpmfile.cjs ./
RUN pnpm install --frozen-lockfile --prod
# Bundle app source
COPY . .
EXPOSE 8080
CMD [ "node", "server.js" ]
As long as there is no change to .npmrc, package.json, pnpm-lock.yaml,
.pnpmfile.cjs, docker build cache is still valid up to the layer of
RUN pnpm install --frozen-lockfile --prod, which cost most of the time
when building a docker image.
However, modification to package.json may happen much more frequently than
we expected, because it does not only contain dependencies, but may also
contain the version number, scripts, and arbitrary configuration for any other
tool.
It's also hard to maintain a Dockerfile that build a monorepo project, it may look like
FROM node:14
RUN curl -f https://get.pnpm.io/v6.16.js | node - add --global pnpm
# Files required by pnpm install
COPY .npmrc package.json pnpm-lock.yaml .pnpmfile.cjs ./
# for each sub-package, we have to add one extra step to copy its manifest
# to the right place, as docker have no way to filter out only package.json with
# single instruction
COPY packages/foo/package.json packages/foo/
COPY packages/bar/package.json packages/bar/
RUN pnpm install --frozen-lockfile --prod
# Bundle app source
COPY . .
EXPOSE 8080
CMD [ "node", "server.js" ]
As you can see, the Dockerfile has to be updated when you add or remove sub-packages.
pnpm fetch will solve the above problem perfectly by providing the ability
to fetch package to virtual store with information only from a lockfile.
FROM node:14
RUN curl -f https://get.pnpm.io/v6.16.js | node - add --global pnpm
# pnpm fetch does require only lockfile
COPY pnpm-lock.yaml ./
RUN pnpm fetch --prod
ADD . ./
RUN pnpm install -r --offline --prod
EXPOSE 8080
CMD [ "node", "server.js" ]
It works for both simple project and monorepo project, --offline enforces
pnpm not to communicate with package registry as all needed packages shall be
already presented in the virtual store.
As long as the lockfile is not changed, the build cache is valid up to the
layer RUN pnpm install -r --offline --prod, which will save you much
time.
Options
--dev
Only development packages will be fetched
--prod
Development packages will not be fetched