# `Puck.Proxy.Sandbox`
[🔗](https://github.com/bradleygolden/puck/blob/v0.2.25/lib/puck/proxy/sandbox.ex#L2)

A sandbox-aware HTTP proxy with domain allowlisting and credential injection.

This is a simple proxy that validates requests against an allowlist and
injects credentials before forwarding with Req.

## Architecture

This proxy runs OUTSIDE the sandbox VM. The sandbox VM:
1. Has network restricted to only reach this proxy (via iptables)
2. Makes requests to `http://proxy:4000/{target_url}`
3. Never sees credentials - they're injected here

## Usage

    # Start with Bandit
    Bandit.start_link(
      plug: {Puck.Proxy.Sandbox, [
        allowed_domains: ["api.anthropic.com", "api.github.com"],
        credentials: %{
          "api.anthropic.com" => [
            {"x-api-key", System.get_env("ANTHROPIC_API_KEY")},
            {"anthropic-version", "2023-06-01"}
          ]
        }
      ]},
      port: 4000
    )

## Request Format

The sandbox sends requests with the target URL in the path:

    POST http://proxy:4000/https://api.anthropic.com/v1/messages
    Content-Type: application/json

    {"model": "claude-3", "messages": [...]}

The proxy:
1. Extracts target URL from path
2. Validates domain against allowlist
3. Injects credentials for that domain
4. Forwards request with Req
5. Streams response back

---

*Consult [api-reference.md](api-reference.md) for complete listing*