config.toml / “runtime” configuration docs have been moved
to the Legacy (V0) section of the Web tab.
LLM\_API\_KEY
* LLM\_MODEL
* **Persistence**
* OH\_PERSISTENCE\_DIR: where OpenHands stores local state (defaults to
\~/.openhands).
* **Public URL (optional)**
* OH\_WEB\_URL: the externally reachable URL of your OpenHands instance
(used for callbacks in some deployments).
* **Sandbox workspace mounting**
* SANDBOX\_VOLUMES: mount host directories into the sandbox (see
[Docker Sandbox](/openhands/usage/sandboxes/docker)).
* **Sandbox image selection**
* AGENT\_SERVER\_IMAGE\_REPOSITORY
* AGENT\_SERVER\_IMAGE\_TAG
* **Sandbox networking (self-hosting behind a reverse proxy)**
* SANDBOX\_CONTAINER\_URL\_PATTERN / OH\_SANDBOX\_CONTAINER\_URL\_PATTERN:
the URL pattern used to reach exposed sandbox ports, with as a
placeholder (default `http://localhost:{port}`). Set this to your public
hostname, e.g. `https://my-domain:{port}`, when self-hosting behind a
reverse proxy. See [Docker Sandbox: Self-hosting behind a reverse proxy](/openhands/usage/sandboxes/docker#self-hosting-behind-a-reverse-proxy).
* AGENT\_SERVER\_USE\_HOST\_NETWORK: when true (also
1/yes), run agent-server containers in Docker host-network
mode so each container's ports are reachable directly on fixed host ports instead of
randomly assigned ones. See [Docker Sandbox: Self-hosting behind a reverse proxy](/openhands/usage/sandboxes/docker#self-hosting-behind-a-reverse-proxy).
## Sandbox provider selection
Some deployments still use the legacy RUNTIME environment variable to
choose which sandbox provider to use:
* RUNTIME=docker (default)
* RUNTIME=process (aka legacy RUNTIME=local)
* RUNTIME=remote
See [Sandboxes overview](/openhands/usage/sandboxes/overview) for details.
## Need legacy options?
If you are looking for the old config.toml reference or V0 “runtime”
providers, see:
* Web → Legacy (V0) → V0 Configuration Options
* Web → Legacy (V0) → V0 Runtime Configuration
# Custom Sandbox
Source: https://docs.openhands.dev/openhands/usage/advanced/custom-sandbox-guide
Build and use your own agent-server image when you need extra tools, system packages, or language runtimes pre-installed in the sandbox.