I've talked about Nix before, but not much about using it in real-world projects.
This month I set up a Nix-based dev environment for a React Native (non-Expo) app running on a POS device. It solved a real pain point for my team, so I wanted to share how we did it.
The problem
Setting up React Native for Android is notoriously tedious. Node, JDK, Android SDK, build tools, environment variables… Each developer installs their own versions, and things break in mysterious ways.
Our hardware made it worse: testing required the actual device and vendor-specific native libraries. Consistency and reproducibility really mattered.
How we used to do it
A lengthy onboarding doc: install this version of Node, that version of JDK, download Android Studio, configure these paths… It took hours, and something always went wrong.
The fix
With Nix, the entire environment is defined in a single file. Following
the Nix Android environment docs, we created a shell.nix file at
the root of the project:
let
# Use OpenJDK 17 for Java builds
jdk = pkgs.javaPackages.compiler.openjdk17;
# Compose a custom Android SDK with only the build tools we need
androidSdk = (pkgs.androidenv.composeAndroidPackages {
buildToolsVersions = [ "34.0.0" ]; # Specify the required build tools version
includeEmulator = false; # Skip the emulator, since we test on real hardware
}).androidsdk;
in
pkgs.mkShell {
buildInputs = with pkgs; [
nodejs_20 # Node.js 20 for React Native
yarn # Yarn package manager
jdk # Java Development Kit
(android-studio.withSdk androidSdk) # Android Studio bundled with our custom SDK
];
JAVA_HOME = jdk.home; # Set JAVA_HOME for tools to find Java
ANDROID_HOME = "${androidSdk}/libexec/android-sdk"; # Set ANDROID_HOME for Android tools
}New developer joins? nix develop. Done. No installation guides, no version mismatches. Everything is isolated to the project, so there are
no
conflicts with other projects or global installs.
Alongside direnv to automatically load the environment when entering the project directory, it made onboarding a breeze.
I was really happy to see that the React Native Metro bundler worked and how simple it was to configure the Android SDK paths. The Nix environment provided all the necessary tools without any additional setup.
New to Nix?
If you’re not familiar with Nix, check out these resources to get started:
You might also consider devenv.sh, which provides a simpler abstraction for managing development environments with Nix.