Asylum

Docker sandbox for AI coding agents. Run Claude Code in a full dev environment — your host stays clean, your tools stay fast. Experimental support for Gemini CLI and Codex.

Asylum wraps Docker to give your AI coding agent a fully-equipped Linux environment with Python, Node.js, Java, Docker-in-Docker, and more. Containers are ephemeral, but caches, auth, shell history, and agent config persist across sessions. A single Go binary, cross-compiled for Linux and macOS (ARM and x86).

Read the documentation →

Install

curl -fsSL https://raw.githubusercontent.com/inventage-ai/asylum/main/install.sh | sh

Or download a binary from the releases page (you'll need to chmod +x it before use).

Requires: Docker installed and running.

Quick Start

cd your-project/

asylum              # Start Claude Code (default)
asylum -a gemini    # Start Gemini CLI
asylum -a codex     # Start Codex
asylum shell        # Interactive shell (no agent)

On first run, Asylum builds a Docker image (~5 min) and seeds agent config from your host. Subsequent runs start in seconds.

Why Asylum?

• Built for Claude Code — first-class support, with experimental Gemini CLI and Codex support
• Docker-in-Docker — build and run containers inside the sandbox
• Real host paths — project mounted at its actual path, so absolute paths and git worktrees work
• Persistent caches — npm, pip, Maven, Gradle caches survive container restarts
• Kit system — modular language/tool bundles you can enable per-project
• Layered config — global defaults, project overrides, local tweaks, CLI flags
• Credential scoping — mount only the host credentials each project needs (read-only)
• Single binary — no runtime dependencies beyond Docker

What's Included

Category	Tools
Python	Python 3, uv, black, ruff, mypy, pytest, poetry
Node.js	LTS via fnm, TypeScript, eslint, prettier, npm/pnpm/yarn
Java	JDK 17/21/25 via mise, Maven, Gradle
Docker	Docker Engine, buildx, compose (Docker-in-Docker)
Dev tools	git, vim, nano, tmux, htop, ripgrep, fd, jq, yq, direnv, gcc, make, cmake
Shell	zsh with oh-my-zsh
GitHub	GitHub CLI (gh)

Everything is modular via Kits — enable what you need, disable what you don't.

Configuration

Layered YAML: ~/.asylum/config.yaml (global) → .asylum (project) → .asylum.local (local) → CLI flags.

agent: gemini

kits:
  java:
    default-version: "17"
    credentials: auto
  docker: {}
  node:
    onboarding: true
    packages:
      - tsx

ports:
  - "3000"

env:
  DEBUG: "true"

Full reference: Configuration documentation

Commands

Command	Description
asylum	Start the default agent
asylum shell	Interactive zsh shell
asylum run <cmd>	Run a command in the container
asylum config	Configure kits, credentials, and isolation
asylum cleanup	Clean up current project (--all for everything)
asylum version	Show version
asylum self-update	Update to latest version

Full reference: Commands documentation

Kits

Kit	Description	Default
node	Node.js LTS + npm/pnpm/yarn	Always on
python	Python 3 + uv	On
java	JDK 17/21/25 + Maven/Gradle	On
docker	Docker-in-Docker	On
github	GitHub CLI	On
shell	oh-my-zsh, tmux, direnv	Always on
ports	Automatic port forwarding	Always on
openspec	OpenSpec CLI	On
ast-grep	AST-based code search (sg)	Opt-in
agent-browser	Browser automation via agent-browser	Opt-in
cx	Semantic code navigation	Opt-in
apt	Extra system packages	Opt-in

See the full kits reference for configuration details.

How Does It Compare?

	Asylum	Claudebox	AgentBox	Safehouse
Approach	Docker container	Docker container	Docker/Podman container	macOS kernel sandbox
Agents	Claude (primary), Gemini, Codex (experimental)	Claude only	Claude, OpenCode	13+ agents
Platform	Linux, macOS	Linux, macOS	Linux, macOS (Bash 4+)	macOS only
Distribution	Single Go binary	Self-extracting installer	Git clone + alias	Homebrew / shell script
Docker-in-Docker	Yes	No	No	N/A
Config	Layered YAML	INI profiles	.env files	.sb policy files
Mount strategy	Real host path	/workspace	Host path	N/A (host-native)
Extensibility	Kit system	Profiles	Single image	Policy profiles

Building from Source

git clone https://github.com/inventage-ai/asylum.git
cd asylum
make build