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Project description

A straightforward but powerful build system based on Ninja and Python, suitable for projects both big and small.

Rōnin comes in frustration-free packaging. Let’s build all the things!


Currently supported out-of-the-box: all gcc languages, Java, Rust, Go, Vala/Genie, pkg-config, Qt tools, sdl2-config, and binutils.

It’s also easy to integrate your favorite testing framework.

“Based on Python” means that not only is it written in Python, but also it uses Python as the DSL for build scripts. Many build systems invent their own DSLs, but Rōnin intentionally uses a language that already exists. There’s no hidden cost to this design choice: build scripts are pretty much as concise and coherent as any specialized DSL. You don’t need to be an expert in Python to use Rōnin, but its power is at your fingertips if you need it.

Rōnin supports Unicode throughout: Ninja files are created in UTF-8 by default and you can include Unicode characters in your build scripts.

Python 3 is recommended, but Rōnin can also run on Python 2.7.


The latest release is available on PyPI, so you can install with pip, easy_install, or setuptools. On Debian/Ubuntu:

sudo apt install python3-pip
sudo -H pip3 install ronin

Since Ninja is just one small self-contained executable, it’s easy to get it by downloading the latest release. Just make sure it’s in your execution path, or run your build script with --set ninja.command= and give it the full path to ninja. Older versions (they work fine) may also be available in your operating system. On Debian/Ubuntu:

sudo apt install ninja-build


An undocumented system is a broken system. We strive for coherent, comprehensive, and up-to-date documentation.

A detailed user manual is available on the wiki.

If you prefer to learn by example, there are many.

Rich API docs available on Read the Docs.


Guiding lights:

  1. Powerful does not have to mean hard to use: optional auto-configuration with sensible, overridable defaults.

  2. Complex does not have to mean complicated: handle cross-compilation and other multi-configuration builds in a single script with minimal duplication of effort.

Design principles:

  1. Don’t hide functionality behind complexity: the architecture should be straightforward. For example, if the user wants to manipulate a compiler command line, let them do it easily. Too many build systems bungle this and make it either impossible or very difficult to do something that would be trivial using a shell script.

  2. Pour some sugar on me: make common tasks easier with sweet utility functions. But make sure that sugar is optional, allowing the script to be more verbose when more control is necessary.

  3. Don’t reinvent wheels: if Python or Ninja do something for us, use it. The build script is a plain Python program without any unnecessary cleverness. The generated Ninja file looks like something you could have created manually.


  • Do we really need another build system? Yes. The other existing ones have convoluted architectures, impossible to opt-out-from automatic features, or are otherwise hostile to straightforward hacking. After so much wasted time fighting build systems to make them work for us, the time came to roll out a new one that does it right.

  • Python is too hard. Why not create a simpler DSL? Others have done it, and it seems that the costs outweigh the benefits. Making a new language is not trivial. Making a robust language could take years of effort. Python is here right now, with a huge ecosystem of libraries and tools. Yes, it introduces a learning curve, but getting familiar with Python is useful for so many practical reasons beyond writing build scripts for Rōnin. That said, if someone wants to contribute a simple DSL as an optional extra, we will consider!

  • Why require Ninja, a binary, instead of building everything in 100% Python? Because it’s silly to reinvent wheels, especially when the wheels are so good. Ninja is a one-trick pony that does its job extremely well. But it’s just too low-level for most users, hence the need for a frontend.

  • Why Ninja? It’s already yesterday’s news! There are even faster builders. Eh, if you ignore the initial configuration phase, and are properly multithreading your build (-j flag in Make), then the time you wait for the build to finish ends up depending on your compiler, not the build system. Ninja was chosen because of its marvelous minimalism, not its speed. Ninja is actually not much faster than Make. For a similarly minimalist build system, see tup.

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