Nix for Reproducible Dev Environments

Thu, 02 Apr 2026 10:00:00 +0300

Every project has a list of dependencies: Go 1.22, Node 20, PostgreSQL 16, protoc, golangci-lint. The traditional approach is a wiki page that says “install these things.” It is always out of date.

Nix solves this by declaring dependencies in a file that deterministically provides the exact versions you need, isolated from the rest of your system.

Getting Started with devenv

devenv is a friendly wrapper around Nix for development environments. Install it:

nix-env -iA devenv -f https://github.com/NixOS/nixpkgs/tarball/nixpkgs-unstable

Create a devenv.nix in your project:

{ pkgs, ... }:

{
 languages.go.enable = true;
 languages.go.package = pkgs.go_1_22;

 packages = [
 pkgs.golangci-lint
 pkgs.buf
 pkgs.postgresql_16
 ];

 services.postgres = {
 enable = true;
 initialDatabases = [{ name = "myapp"; }];
 };
}

Enter the environment:

devenv shell

You now have the exact Go version, tools, and a running PostgreSQL instance. No global installs. No version conflicts.

direnv Integration

Add a .envrc file:

use devenv

Now every time you cd into the project, your shell automatically loads the right tools. Leave the directory, and they disappear.

Why This Matters

New team members run devenv shell and they are ready. No setup docs.
CI uses the same Nix definitions, so local and CI environments are identical.
Upgrading a tool is a one-line change in devenv.nix, reviewed in a PR like any other code change.

Reproducibility on hxmn.dev

Nix for Reproducible Dev Environments

Getting Started with devenv

direnv Integration

Why This Matters