subatomic & kiritan

subatomic is the modern package delivery system for RPMs. v1 of subatomic (satm1) is written in Rust, and comes with an extremely fast repodata generator, around 10× faster and 30× more memory efficient than createrepo_c with cache.¹

• Repodata generation is also available via a separate binary kiritan.
• Interact with the API via the satm command.
• satm, kiritan, and the backend libsubatomic are inside the crates/ directory.

Note

v0 of subatomic (satm0) was written in Go. You may find the source code in the v0 branch.

🏗️ Building

Requires Rust nightly.

You should compile with clang to enable fat-LTO for zstd. See https://lib.rs/crates/zstd-sys/features#feature-fat-lto.

📃 License

Copyright (C) 2026  Fyra Labs

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.

⚙ Configuration

The subatomic server (subatomic) reads the following (latter has higher priority):

• subatomic.toml
• environment variables (uppercase keys required)

Syntax for environment variables are documented by figment::providers::Env, which mentions support for even arrays and objects.

Latest options and their default values are in src/config.rs. Here is a documented list of options, default values, and other possible values:

• server_host: "localhost", 0.0.0.0, ...
• server_port: 3000
• database_url
• db_max_conns: 32
• jwt_secret
• cache_dir: ./kiritanpo-nabe/
• body_limit: 1073741824 (1 GiB)
• storage: local, aws
• hierarchy: Satm0Flat { base: "./subatomic-repos/" }, Fedora { base }
• compression: zstd { level: 0, multi: 0 }, xz { level, multi }

Footnotes

1. See our blog for the benchmark: https://blog.fyralabs.com/kiritan-10x-faster-alternative-to-createrepo_c/ ↩