Docker installation advice with manage-package-manager-versions and pnpm fetch

[RobHannay]

We recently migrated away from Corepack, to use pnpm's built-in version manager based off the packageManager field.

This works great except in our Docker builds, where we do the fetch/install as described in the docs here.

RUN wget -qO- https://get.pnpm.io/install.sh | env PNPM_VERSION=10.1.0  ENV="$HOME/.bashrc" SHELL="$(which bash)" bash -
RUN source $HOME/.bashrc
RUN pnpm config set store-dir /root/.local/share/pnpm/store

# Copy in lockfile, pull across any patched package and install deps
# Do this separately from the source to improve docker layer caching
COPY pnpm-lock.yaml .
COPY patches/ ./patches

RUN --mount=type=cache,id=pnpm,target=/root/.local/share/pnpm/store \
    pnpm fetch

# Now copy everything else
COPY . .

ENV CI=true

FROM common-cache AS build

RUN --mount=type=cache,id=pnpm,target=/root/.local/share/pnpm/store \
    pnpm install --filter "$PROJECT" --ignore-scripts --offline

(I only added the PNPM_VERSION env as a workaround to help us upgrade to v10 and not use Corepack)

The problem is that when updating the packageManager field in package.json, it fails at pnpm install, because it cannot fetch the requested version from the local cache - even though it would have downloaded it online at pnpm fetch.

What is the best-practice recommend approach? Is it actually a bug that pnpm doesn't cache its own versions?

I find the docs recommend a few different approaches with Docker. I'd be happy to contribute back to the docs once there's a suggestion we agree works

[rsahrakorpi-cambri]

I've been encountering similar. From my testing it is the combination of --offline and --filter that doesn't work.

If you remove the filter and just have offline it works as expected and installs from the cache. if you remove the offline (or change it to prefer-offline) the filter works, but it refetches everything and ignores the store. So it appears to be a bug where these 2 flags can't be used together