pixi-make-offline-channel

name	pixi-make-offline-channel
description	Use when the user wants to create a self-hosted, offline-installable Conda channel (mirror) containing a specific subset of packages using Pixi.

Pixi Make Offline Channel

Trigger

Use this skill when the user asks to:

• "Create a local conda channel with pixi"
• "Mirror a subset of conda packages for offline use"
• "Download conda packages and dependencies using pixi"
• "Create a self-hosted conda-forge mirror"

Overview

This skill guides the user to creating a custom, self-hosted Conda channel (mirror) that contains only a selected subset of packages but includes all transitive dependencies. This ensures the channel is fully installable on offline machines.

The workflow uses Pixi's lockfile (pixi.lock) as the source of truth for dependency resolution and rattler-index for generating channel metadata.

Workflow

1. Setup Builder Project

Create a temporary "builder" project to define the package set. This project will not be used for running code, but for resolving the dependency tree.

mkdir my-mirror-builder
cd my-mirror-builder
pixi init

2. Define Package Subset

Add the target packages you want to mirror. Also add the necessary build tools (rattler-index and pyyaml) to the environment.

# Target packages to mirror
pixi add pandas scikit-learn pytorch

# Tools required for the mirroring process
pixi add rattler-index pyyaml requests

3. Fetch Artifacts (The "Mirror Script")

Use a Python script to parse pixi.lock, extract the exact URLs for all resolved dependencies, and download them into a standard channel structure (e.g., channel/linux-64/).

Key Steps for the Script:

1. Read pixi.lock (YAML format).
2. Iterate through packages.
3. Download the file at url to output_dir/<platform>/<filename>.

Ref: See context/hints/howto-create-self-hosted-conda-subset-repo-with-pixi.md for the complete build_mirror.py script.

4. Index the Channel

After downloading all artifacts, use rattler-index to generate the repodata.json. This turns the directory into a valid Conda channel.

pixi run rattler-index local-channel

5. Verify & Consume

The channel is now ready. It can be used via file:// or hosted via HTTP.

Verification:

# Create a test env using ONLY the local channel
conda create -n test-offline -c file://$(pwd)/local-channel pandas --offline --override-channels

Tips

• Multi-Platform: To support multiple platforms (e.g., linux-64 AND osx-arm64), manually edit pixi.toml to include them (platforms = ["linux-64", "osx-arm64"]) and run pixi lock before running the download script.
• Updates: To update the mirror, simply pixi update the builder project, re-run the download script (it should skip existing files), and re-run rattler-index.
• Pixi-Pack: If the goal is just to move one environment, suggest pixi-pack instead. This skill is for creating a reusable channel.

Resources

• howto-create-self-hosted-conda-subset-repo-with-pixi.md: Detailed step-by-step guide with the full Python script.