lsst-conda-repackager

Repackage the LSST Science Pipelines into a standard conda package, eliminating EUPS from the user experience entirely.

What this does

The LSST Science Pipelines normally require a multi-step installation involving lsstinstall, EUPS (a custom package manager), and a setup command that must be run in every new shell. This tool automates a full EUPS-based install, relocates all the installed products into a conda-native directory layout, and builds a single conda package from the result.

After a one-time build, users install the entire stack with:

conda create -n lsst -c file:///path/to/local/channel -c conda-forge lsst-distrib==30.0.7
conda activate lsst

No eups, no loadLSST.sh, no setup command.

Repository contents

File	Purpose
build-lsst-conda.sh	Top-level orchestrator — drives the full build pipeline
lsst_relocator.py	Merges EUPS product trees into a flat conda-compatible prefix
setup-conda.sh	Installs/activates a local Miniforge3, isolated from user environments
install-patchelf.sh	Downloads a local copy of patchelf (no root required)

Prerequisites

• Linux x86_64 (tested on Rocky 9)
• curl
• Network access to eups.lsst.codes and conda-forge
• Sufficient disk space (~10–15 GB for the build working directory)

Everything else (Miniforge, conda-build, patchelf) is bootstrapped automatically.

Quick start

# Clone or copy the scripts to your build machine
cd /path/to/lsst-conda-repackager

# Build a package for a specific release tag
./build-lsst-conda.sh \
    --tag v30_0_7 \
    --product lsst_distrib \
    --channel /data/conda/lsst-local

# The channel directory now contains a ready-to-use conda package.

Build options

Flag	Default	Description
--tag TAG	(required)	EUPS release tag (e.g. v30_0_7, w_2026_20)
--channel DIR	(required)	Output directory for the local conda channel
--product PRODUCT	lsst_distrib	Top-level EUPS product to package
--build-dir DIR	/tmp/lsst-conda-build-PID	Working directory (removed on success)
--keep-build	off	Preserve the build directory for debugging

Installing the package

Configure conda to see the local channel, either per-command:

conda create -n lsst -c file:///data/conda/lsst-local -c conda-forge lsst-distrib==30.0.7
conda activate lsst

Or permanently via ~/.condarc:

channels:
  - file:///data/conda/lsst-local
  - conda-forge

Then simply:

conda create -n lsst lsst-distrib==30.0.7
conda activate lsst

How it works

The build pipeline has four stages:

1. EUPS installation

A local Miniforge environment is created (completely isolated from any user conda), and a standard LSST install is performed inside it using lsstinstall and eups distrib install. This is the same process described in the official LSST install docs, just automated.

2. Relocation

EUPS installs each product into its own directory tree. The relocator walks every installed product and merges files into a single conda-compatible prefix layout:

EUPS location	Conda location
<product>/python/lsst/...	lib/python3.X/site-packages/lsst/...
<product>/lib/*.so	lib/ (RPATHs patched to $ORIGIN)
<product>/bin/*	bin/ (shebangs fixed)
<product>/include/*	include/
<product>/{policy,config,data,schema,pipelines}/*	share/lsst/<product>/

A conda activation script is generated that sets <PRODUCT>_DIR environment variables for every product, so that lsst.utils.getPackageDir() continues to work.

Build artifacts (object files, CMake/meson build trees, test binaries, generated documentation, pytest caches, EUPS metadata) are filtered out during relocation.

3. Conda build

A meta.yaml recipe is generated with a dependency on the exact rubin-env version used during the EUPS install. conda-build packages the relocated files into a .tar.bz2.

4. Channel indexing

The package is placed in the channel directory and conda index is run to generate repodata.json.

Environment isolation

The build pipeline is hermetically sealed from your personal conda environments. setup-conda.sh deactivates any active conda, scrubs all conda/mamba environment variables from the shell, removes conda paths from $PATH, and then installs or activates a dedicated Miniforge under ./miniforge3. The lsstinstall script is explicitly pointed at this Miniforge via -p.

Tools that need to survive the LSST environment taking over $PATH (patchelf, conda-build, conda itself) are resolved to absolute paths before source loadLSST.sh runs.

Known limitations and future work

Build artifact filtering. Some EUPS products (notably gauss2d, gauss2d_fit, gbdes, kht) include build trees and generated docs in their installed directories. The relocator filters the most common patterns, but unusual layouts may still leak through. The resulting package works correctly but may be larger than necessary.

PRODUCT_DIR variables. The activation script sets ~100 environment variables. This is functional but verbose. A future improvement would be to patch lsst.utils.getPackageDir() to fall back to $CONDA_PREFIX/share/lsst/<product>/ when the variable isn't set.

Developer workflow. This tool targets users running the pipelines, not developers modifying LSST source code. Developers should continue using the EUPS workflow or overlay their changes on top of a conda-installed stack.

Package size. A full lsst_distrib package is large. If needed, it could be split into a runtime package and a -devel package (headers, static libraries).

Platform support. Currently builds for linux-64 only. macOS support would require equivalent install_name_tool handling in the relocator.

Version mapping

EUPS tag format	Example	Conda version
Release	v30_0_7	30.0.7
Weekly	w_2026_20	2026.20.0

The conda package depends on the corresponding rubin-env version from conda-forge (e.g. rubin-env==12.2.0), which provides all external dependencies (Python, NumPy, Astropy, compilers, FFTW, etc.).