dev-sandbox

Developer sandbox offers a lightweight isolated environment using Bubblewrap. It’s designed to keep your host data isolated while you (or AI coding assistants) run tools inside a minimal, network-enabled container.

• 🛡️ Isolation via bwrap
• 📦 Packaged as a Nix flake
• 🛒 Provides convenient shell, claude, and codex sandboxes
• 🔧 Build-time configuration:
  • runCommand — command to run inside the sandbox. Defaults to your current shell.
  • binds — list of paths to expose. Equivalent to bwrap --bind. Can either be a string path where the same path is bound inside the sandbox or a two-element list [ src dst ].
  • roBinds — list of paths to expose as read only. Equivalent to bwrap --ro-bind.
  • symlinks — attrset of symlinks to create inside the sandbox. Keys are link paths, values are targets. Equivalent to bwrap --symlink TARGET LINK.
  • envs — key/value pairs. Equivalent to brwap --setenv KEY VALUE.
  • extraArgs — extra bwrap flags to append.
• Sets DEV_SANDOX env var to allow you to detect when sandbox is active.
  • For example, you can use this to change your prompt to indicate when you are in the sandbox.

• Nix package manager with flakes enabled.
• 🐧 Linux (x86_64-linux, aarch64-linux). Tested on NixOS. Should work on other Linux distros, but not tested.

Add to your flake.nix inputs:

{
  inputs.dev-sandbox.url = "github:champloo/dev-sandbox";
  inputs.dev-sandbox.inputs.nixpkgs.follows = "nixpkgs";

  # And add to your modules

      modules = [ inputs.dev-sandbox.nixosModules.default ];
}

Then in your configuration.nix:

{ inputs, pkgs, ... }:

{
  programs.dev-sandbox = {
    # Common settings applied to all sandbox variants
    binds = [
      "$HOME/.cache/uv"
    ];
    roBinds = [
      "$HOME/.zshrc"
    ];
    symlinks = {
      # Example: ensure /usr/bin/python exists inside sandbox
      "/usr/bin/python" = "/nix/store/.../bin/python";
    };
    envs = {
      EDITOR = "nano";
    };

    # Enable shell sandbox which can be run with dev-sandbox
    default = {
      enable = true;
      # Inherits common settings above
    };

    # Enable Claude Code sandbox which can be run with dev-sandbox-claude
    claude = {
      enable = true;
      # Defaults are pre-configured:
      #   name = "dev-sandbox-claude"
      #   runCommand = [ "claude" "--dangerously-skip-permissions" ]
      #   binds = [ "$HOME/.claude.json" "$HOME/.claude" ]
      #   extraRuntimeInputs = [ pkgs.claude-code ]
      #
      # You can override or extend any defaults:
      # name = "claudebox"; # also changes name of the binary
      # binds = [ "$HOME/.custom-claude-config" ];
    };

    # Enable Codex sandbox which can be run with dev-sandbox-codex
    codex = {
      enable = true;
      # Defaults are pre-configured:
      #   name = "dev-sandbox-codex"
      #   runCommand = [ "codex" "-a" "never" "-s" "danger-full-access" ]
      #   binds = [ "$HOME/.codex" ]
      #
      # You can override or extend any defaults:
      # binds = [ "$HOME/.custom-codex-config" ];
    };
  };
}

This creates three executables:

• dev-sandbox - plain shell sandbox
• dev-sandbox-claude - Claude Code sandbox
• dev-sandbox-codex - Codex sandbox

All will be available in your system PATH.

If you just want to try it out with the default config you can...

nix run github:champloo/dev-sandbox

Run the Claude Code variant:

NIXPKGS_ALLOW_UNFREE=1 nix run github:champloo/dev-sandbox#claude --impure

Run the Codex variant:

nix run github:champloo/dev-sandbox#codex

• Read/write: the current directory, synthetic home and tmp at /tmp/dev-sandbox-home-$$ and /tmp/dev-sandbox-tmp-$$, /etc/resolv.conf, /etc/nix, /etc/static/nix.
• Read-only: /nix, /bin/sh, /usr/bin/env, and on NixOS systems /run/current-system/sw.
• PATH, HOME, USER, LOGNAME, TERM environment variables.
  • cacert is installed as a dependency and the relevant cert env vars are pointed to the installed ca-bundle.crt file.

• https://github.com/numtide/nix-ai-tools/blob/main/packages/claudebox/claudebox.sh
• https://github.com/longregen/claude-sandbox
• https://github.com/Naxdy/nix-bwrapper
• https://github.com/fgaz/nix-bubblewrap