nix-diff-rs

A Rust port of nix-diff, a tool to explain why two Nix derivations differ.

Features

• Compare two Nix derivations and show their differences
• Support for multiple input types:
• .drv files (pre-built derivations)
• Realized store paths
• .nix files (will be instantiated automatically)
• Flake references (e.g., nixpkgs#hello, path:/path/to/flake#package)
• Colored output with support for NO_COLOR environment variable
• Delta-style inline word highlighting (shows what changed in each line)
• Minimal dependencies

Installation

nix run github:Mic92/nix-diff-rs

Usage

nix-diff [OPTIONS] <INPUT1> <INPUT2>

Arguments:
  <INPUT1>    First input (.drv file, store path, .nix file, or flake#attr)
  <INPUT2>    Second input (.drv file, store path, .nix file, or flake#attr)

Options:
  --color <MODE>         Color mode: always, auto, never (default: auto)
  --no-inline-highlight  Disable word-level highlighting within changed lines
  --context <LINES>      Number of context lines (default: 3)
  --input-list-limit <N> Max added/removed inputs to list (default: 10)
  --depth <N>            Max recursion depth into input derivations
  -v, --verbose          Show output-path changes and full input lists
  -h, --help             Show this help message

By default, the output hides mechanical noise such as output-path changes (which differ whenever anything else differs) and env vars that mirror output paths ($out, $dev, ...). Use --verbose to show everything, or --depth N to limit how deep the diff recurses into dependencies.

When color is enabled, changed words within changed lines are highlighted with reverse-video (like delta or diff-so-fancy), so you can instantly spot store-path hash changes and version bumps without scanning full lines.

Examples

Compare two derivations:

nix-diff /nix/store/abc123-hello.drv /nix/store/def456-hello.drv

Compare realized store paths:

nix-diff /nix/store/abc123-hello /nix/store/def456-hello

Compare Nix files (will be instantiated automatically):

nix-diff hello.nix goodbye.nix

Compare flake outputs:

# Compare packages from flakes
nix-diff nixpkgs#hello nixpkgs#hello-wayland

# Compare local flake outputs
nix-diff .#packages.x86_64-linux.myapp .#packages.x86_64-linux.myapp-dev

# Compare using flake paths
nix-diff path:/path/to/flake1#package path:/path/to/flake2#package

Limit recursion depth (useful when stdenv changed and you only care about the top-level differences):

nix-diff --depth 1 nixpkgs/nixos-25.11#hello nixpkgs/nixos-unstable#hello

Disable colors:

nix-diff --color never input1 input2
# or
NO_COLOR=1 nix-diff input1 input2

Development

# Enter development shell
nix develop

# Build
cargo build

# Run tests
cargo test

# Run benchmarks
cargo bench

# Format code
nix fmt

License

BSD-3-Clause (same as the original nix-diff)