CI and offline use

jup can download a project's package manager before a build starts, then run entirely from its local cache. This makes package manager installation repeatable in CI, containers, and isolated environments.

#Cache the project package manager

Run this while the registry is available:

jup install

jup reads the current project pin and downloads that release without changing package.json.

To prove that later commands do not use the network:

JUP_ENABLE_NETWORK=0 pnpm install

A missing cache entry produces an error that names the required package manager and version.

#Use jup in CI

A typical CI job installs jup, warms its cache, and then disables network access for package manager resolution:

jup install
JUP_ENABLE_NETWORK=0 pnpm install --frozen-lockfile

Cache JUP_HOME between jobs if your CI service supports persistent caches. Run jup info to find its effective path.

If packageManager contains a range, commit .corepack.lock. When CI is set, jup refuses to create or update a range resolution by default. Refresh it locally with jup up, review the diff, and commit the result.

Set JUP_FROZEN_LOCKFILE=0 only when a CI job is intentionally responsible for updating .corepack.lock.

#Build a container image

Copy the files that select the package manager before copying the rest of the project:

COPY package.json ./
RUN jup install

ENV JUP_ENABLE_NETWORK=0
COPY . .
RUN pnpm install

For a range pin, include its resolution file in the first layer:

COPY package.json .corepack.lock ./
RUN jup install

The package manager remains in a reusable image layer until the pin changes.

#Cache a specific release

To cache one release without changing a project pin or global fallback:

jup install -g --cache-only pnpm@11.1.2

Check the result with:

jup cache list

#Prepare an offline archive

On a connected machine, create an archive:

jup pack -o package-managers.tgz pnpm@11.1.2

Copy it to the isolated machine and import it:

jup install -g package-managers.tgz
jup cache list

jup pack also records the packed version as that manager's global fallback. A fallback applies only when a project has no package manager pin.

#Clear cached package managers

Remove downloaded versions while keeping global fallback records and cached signing keys:

jup cache clean

Remove downloaded versions and fallback records together:

jup cache clean --all

The next command that needs a removed release must download it again. For details about what jup checks before caching a download, read Download verification.