conda-lock vs Spack

conda-lock is a lightweight library for producing reproducible lockfiles for conda environments. It solves dependencies separately for each target platform, allowing installations from generated lockfiles to avoid running the conda solver. Inputs can come from environment.yml, conda-build meta.yaml, or pyproject.toml dependency specifications. Its default unified lockfile covers multiple platforms and can be rendered into other lockfile formats. Documented target examples include Linux, macOS, Windows, and additional Linux architectures. The project describes use alongside conda, mamba, pip, Docker, and pixi, and provides installation routes through pip, conda, and mamba; pipx or condax are recommended for isolated installation. Mixed conda-and-pip locking is experimental. Channel access supports token or basic authentication, with environment-variable substitution for credentials. The unified lockfile can omit raw credential-bearing channel URLs when it matches credential portions to environment variables, although rendered explicit lockfiles may contain substituted variables. Private pip repository support is limited to legacy PyPI repositories using basic authentication. The software is MIT-licensed and free.

Spack is a package manager for installing scientific software on supercomputers, Linux, macOS, and Windows. It is designed for large supercomputing centers that share software across clusters and varied architectures, and is available at free. Users can choose package versions, compiler choices, target architectures, and compile-time options, while controlling direct and transitive dependencies. Spack can build stacks that combine Python or R packages with C, C++, or Fortran libraries. Each distinct package and dependency configuration receives its own prefix, so different builds can coexist without a new installation disrupting an existing one. Software can be installed to a user-selected directory without administrator privileges. Spack primarily builds customized software from source and also supports binary installation through build caches. It supports lockfiles, environment management, and private registries. Package recipes are Python scripts, and the `spack create` command generates starter boilerplate. The project is distributed under either the MIT license or Apache License 2.0, at the user's option.