Docker Claude Code Sandbox

Execute Claude Code in isolated Docker containers with AI-powered code generation using the Claude Agent SDK.

Quick Start

1. Install Docker

Ensure Docker is installed and running on your system:

# Check Docker installation
docker --version

# Verify Docker daemon is running
docker ps

If Docker is not installed, visit: https://docs.docker.com/get-docker/

2. Configure API Key

Set your Anthropic API key:

# Set as environment variable
export ANTHROPIC_API_KEY=sk-ant-your-api-key-here

# Or pass directly when using the CLI
npx claude-code-templates@latest --sandbox docker \
  --agent development/frontend-developer \
  --prompt "Create a React component" \
  --anthropic-api-key sk-ant-your-key

3. Run Your First Sandbox

# Basic execution
npx claude-code-templates@latest --sandbox docker \
  --prompt "Write a function to calculate factorial"

# With specific agent
npx claude-code-templates@latest --sandbox docker \
  --agent development/python-developer \
  --prompt "Create a data validation script"

# With multiple components
npx claude-code-templates@latest --sandbox docker \
  --agent development/fullstack-developer \
  --command development/setup-testing \
  --prompt "Set up a complete testing environment"

Architecture

This sandbox combines two powerful technologies:

1. Claude Agent SDK - Provides programmatic access to Claude Code
2. Docker - Provides isolated container execution

User Prompt → Docker Launcher → Container Build → Execute Script → Claude Agent SDK → Output Files

Components

docker/
├── docker-launcher.js   # Node.js launcher that orchestrates Docker
├── Dockerfile           # Container definition with Claude Agent SDK
├── execute.js           # Script that runs inside container
├── package.json         # Dependencies (Claude Agent SDK)
└── README.md           # This file

How It Works

1. Launcher Phase (docker-launcher.js)

• Checks Docker installation and daemon status
• Builds container image if it doesn't exist
• Prepares environment variables and volume mounts
• Launches container with user prompt

2. Container Phase (execute.js)

• Installs requested components (agents, commands, MCPs, etc.)
• Executes Claude Agent SDK with the user's prompt
• Auto-allows all tool uses (no permission prompts)
• Captures output and generated files
• Copies results to mounted output directory

3. Output Phase

• Generated files are saved to output/ directory
• Files preserve directory structure
• Accessible on host machine for inspection

Usage Examples

Simple Code Generation

npx claude-code-templates@latest --sandbox docker \
  --prompt "Create a REST API server with Express.js"

With Specific Agent

npx claude-code-templates@latest --sandbox docker \
  --agent security/security-auditor \
  --prompt "Audit this codebase for security vulnerabilities"

Multiple Components

npx claude-code-templates@latest --sandbox docker \
  --agent development/frontend-developer \
  --command testing/setup-testing \
  --setting performance/performance-optimization \
  --prompt "Create a React app with testing setup"

Development Workflow

# 1. Generate initial code
npx claude-code-templates@latest --sandbox docker \
  --agent development/fullstack-developer \
  --prompt "Create a blog API with authentication"

# 2. Check output
ls -la output/

# 3. Iterate on generated code
npx claude-code-templates@latest --sandbox docker \
  --prompt "Add pagination to the blog API"

Configuration

Environment Variables

Required:

• ANTHROPIC_API_KEY - Your Anthropic API key

Optional:

• DOCKER_BUILDKIT=1 - Enable BuildKit for faster builds

Docker Image Details

The Docker image (claude-sandbox) includes:

• Base: Node.js 22 Alpine Linux (minimal, secure)
• Runtime: Git, Bash, Python3, Pip, Curl
• Claude SDK: @anthropic-ai/claude-agent-sdk installed globally
• Security: Runs as non-root user (UID 10001)
• Working Directory: /app
• Output Directory: /output (mounted as volume)

Build Configuration

Edit Dockerfile to customize:

# Add additional system dependencies
RUN apk --no-cache add postgresql-client redis

# Install additional global npm packages
RUN npm install -g typescript tsx

# Set custom environment variables
ENV CUSTOM_VAR=value

Command Reference

Build Image Manually

cd .claude/sandbox/docker
docker build -t claude-sandbox .

Run Container Directly

docker run --rm \
  -e ANTHROPIC_API_KEY=$ANTHROPIC_API_KEY \
  -v $(pwd)/output:/output \
  claude-sandbox \
  node /app/execute.js "Your prompt here" ""

Clean Up

# Remove built image
docker rmi claude-sandbox

# Remove all stopped containers
docker container prune

# Remove dangling images
docker image prune

Troubleshooting

Docker Not Found

Error: Docker is not installed

Solution:

# Install Docker from official site
# macOS: https://docs.docker.com/desktop/install/mac-install/
# Linux: https://docs.docker.com/engine/install/
# Windows: https://docs.docker.com/desktop/install/windows-install/

Docker Daemon Not Running

Error: Docker daemon is not running

Solution:

# macOS/Windows: Start Docker Desktop application
# Linux: sudo systemctl start docker

API Key Not Set

Error: ANTHROPIC_API_KEY environment variable is required

Solution:

export ANTHROPIC_API_KEY=sk-ant-your-key-here

Build Failures

Error: Failed to build Docker image

Solution:

# Check Docker logs
docker logs <container-id>

# Rebuild from scratch
docker build --no-cache -t claude-sandbox .

# Check disk space
docker system df

Permission Issues

Error: Permission denied when accessing output files

Solution:

# Check output directory permissions
ls -la output/

# Fix permissions (if needed)
sudo chown -R $USER:$USER output/

Container Execution Failures

Error: Container failed with code 1

Solution:

# Run container interactively for debugging
docker run -it --rm \
  -e ANTHROPIC_API_KEY=$ANTHROPIC_API_KEY \
  claude-sandbox \
  /bin/bash

# Check container logs
docker logs <container-id>

Performance Tips

1. Image Caching: First build takes longer, subsequent builds are fast
2. Volume Mounts: Use volumes instead of COPY for faster iteration
3. Layer Optimization: Group RUN commands to reduce image layers
4. BuildKit: Enable for parallel builds (DOCKER_BUILDKIT=1)
5. Prune Regularly: Clean up unused images and containers

Security

• Isolation: Containers are isolated from host system
• Non-root User: Execution runs as sandboxuser (UID 10001)
• No Network: Container has no internet access (except during build)
• Read-only: Host filesystem is mounted read-only
• Resource Limits: Docker enforces CPU and memory limits
• Secret Management: API keys are passed as environment variables (not stored in image)

Cost Estimation

Docker:

• Free and open-source
• No cloud costs (runs locally)
• Resource usage: ~500MB disk space, ~512MB RAM during execution

Anthropic API:

• Claude Sonnet 4.5: ~$3 per million input tokens
• Average request: ~200 tokens = $0.0006 per request

Example costs for 100 executions:

• Docker: $0 (local execution)
• Anthropic: ~$0.06 (avg 200 tokens/request)
• Total: ~$0.06

Comparison with Other Providers

Development

Project Structure

docker/
├── docker-launcher.js   # Orchestrates container lifecycle
│   ├── checkDockerInstalled()
│   ├── checkDockerRunning()
│   ├── buildDockerImage()
│   └── runDockerContainer()
├── Dockerfile           # Container definition
│   ├── Base image (Node 22 Alpine)
│   ├── System dependencies
│   ├── Claude Agent SDK
│   └── Security (non-root user)
├── execute.js           # Execution script (runs in container)
│   ├── installComponents()
│   ├── executeQuery()
│   └── copyGeneratedFiles()
├── package.json         # NPM dependencies
└── README.md           # Documentation

Scripts

# Build image
npm run build

# Clean image
npm run clean

Extending the Image

Add custom tools to the Dockerfile:

# Install Python packages
RUN pip install --no-cache-dir pandas numpy matplotlib

# Install Node.js packages globally
RUN npm install -g typescript eslint prettier

# Add custom scripts
COPY scripts/ /app/scripts/

Advanced Usage

Custom Dockerfile

Create a custom Dockerfile for specialized environments:

FROM node:22-alpine

# Install database clients
RUN apk add --no-cache postgresql-client mysql-client

# Install development tools
RUN apk add --no-cache vim nano tmux

# Install Claude Agent SDK
RUN npm install -g @anthropic-ai/claude-agent-sdk

# ... rest of configuration

Multi-stage Builds

Optimize image size with multi-stage builds:

# Build stage
FROM node:22-alpine AS builder
WORKDIR /build
COPY package*.json ./
RUN npm ci --only=production

# Runtime stage
FROM node:22-alpine
COPY --from=builder /build/node_modules ./node_modules
# ... rest of configuration

Persistent Storage

Mount additional volumes for persistent data:

docker run --rm \
  -e ANTHROPIC_API_KEY=$ANTHROPIC_API_KEY \
  -v $(pwd)/output:/output \
  -v $(pwd)/cache:/cache \
  claude-sandbox

Resources

• Docker Documentation
• Claude Agent SDK
• Anthropic API Documentation
• Docker Best Practices
• Container Security

License

MIT License - See LICENSE file for details

Support

For issues and questions:

1. Check Docker installation: docker --version && docker ps
2. Verify API key: echo $ANTHROPIC_API_KEY
3. Check container logs: docker logs <container-id>
4. Review output directory: ls -la output/
5. Open an issue on GitHub

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Built with ❤️ using Docker, Node.js, and Claude Agent SDK