Packing

Packing for Air-Gapped Hosts

Some machines can't reach your conda channels — isolated build hosts, secure enclaves, offline labs. Packing bundles everything an environment needs into one file you can copy across the gap and install with no network and no conda.

A bundle is a .tar archive containing the lock, a manifest, and every package archive the lock pins:

nepenthe-pack.yml     # format, environment, platforms, packages (file + sha256 + size)
environment.lock      # the lock that was packed
pkgs/<filename>       # every .conda / .tar.bz2 the lock references

Packages inside .conda archives are already compressed, so the outer tar is left uncompressed.

Pack (on a connected host)

pack reads a lock, downloads every package it pins, verifies each against the lock's recorded sha256, and writes the bundle:

# pack every platform the lock covers for the "app" environment
nepenthe pack --lock app.lock --env app --output app.tar
# packed app (linux-64) — 39 packages, 65.6 MiB → app.tar

# …or restrict to specific platforms (repeat --platform)
nepenthe pack --lock app.lock --env app \
  --platform linux-64 --platform osx-arm64 --output app.tar

A lock with multiple platforms shares noarch packages between them, so they are bundled once.

Unpack (on the air-gapped host)

Copy the .tar across, then install from it. unpack extracts the bundle, rewrites every package URL to the bundle's local copy, and installs into a prefix — offline, no conda:

nepenthe unpack --pack app.tar --prefix ./envs/app
# installed app (linux-64) at ./envs/app — 39 packages

# the environment defaults to the bundle's; override env/platform if needed
nepenthe unpack --pack app.tar --prefix ./envs/app \
  --env app --platform linux-64 --stage-dir ./unpacked

By default the bundle is extracted to a temporary directory that is removed after the install. Pass --stage-dir to keep the extracted packages (e.g. to install several prefixes from one bundle without re-extracting).

The installed prefix is byte-identical to one created online from the same lock — diff against the lock comes back empty.

From Python

import nepenthe

# producer host
summary = nepenthe.pack("app.lock", "app", "app.tar")          # all platforms
summary = nepenthe.pack("app.lock", "app", "app.tar", platforms=["linux-64"])
print(summary["packages"], summary["bytes"])

# air-gapped host
nepenthe.unpack("app.tar", "./envs/app")                        # offline install
nepenthe.unpack("app.tar", "./envs/app", env="app", platform="linux-64")

See the Python API for the full surface.

How it works

• Integrity end to end. Every package is verified against the lock's sha256 at pack time; rattler re-verifies the same hash when linking from the bundle at install time. A corrupt or tampered package is rejected.
• No conda, no re-solve. unpack rewrites each lock record's URL to a file:// path inside the bundle; rattler's installer reads the local archive directly (get_or_fetch_from_path) and links it into the prefix.
• Reproducible. The bundle carries the exact lock, so the air-gapped install matches the online one package for package.

Limitations

• Authenticated channels. Package downloads during pack are unauthenticated. Packing from a channel that requires credentials is not yet supported — pack from a public or already-permitted mirror. (Tracked for a future release.)
• Size. A bundle contains the full package set, so it is as large as the environment (tens to hundreds of MiB). This is the cost of being self-contained.