Configuration reference

Configure Modal orchestration with ComputerConfig and configure a direct daemon with environment variables.

Version 1.1.0 has two configuration surfaces.

• ComputerConfig configures SDK-created Modal Sandboxes.
• Environment variables configure the daemon process.

ComputerConfig does not read a config file or process environment. Pydantic defaults apply first. Explicit model values replace those defaults.

Public SDK model

from modal_computer_use import (
    ActionConfig,
    BrowserConfig,
    ComputerConfig,
    ResourceConfig,
    RuntimeConfig,
)

config = ComputerConfig(
    runtime=RuntimeConfig(modal_region="us-west-2"),
    resources=ResourceConfig(cpu=1, memory_mib=2048),
    browser=BrowserConfig(kind="chromium", prewarm=True),
    actions=ActionConfig(
        input_backend="auto",
        subprocess_backend="isolated-asyncio",
    ),
)

All configuration models reject unknown keys.

Model	Owns
DesktopConfig	Resolution, DPI, window manager, and display depth
RuntimeConfig	Sandbox timeout, idle timeout, readiness timeout, Modal environment, and requested region
ResourceConfig	Image profile, CPU, memory, and GPU requests
ImageConfig	Inline or named image selection and revision
NetworkConfig	Network policy, daemon HTTP version, and allowlists
StorageConfig	Artifact, recording, trace, and persistence paths
BrowserConfig	Browser kind, prewarm, profile, startup URL, launch arguments, and GPU mode
ActionConfig	Pacing, traces, batch limits, timeouts, input rate, input backend, and subprocess backend
BudgetConfig	Action, screenshot, artifact, recording, and idle budgets
ComputerConfig	The nested models, ingress, run identity, and VNC policy

See the v1.1.0 configuration source for field signatures.

Important defaults

Setting	Default
Resolution	1024 x 768
Runtime timeout	3600 seconds
Readiness timeout	120 seconds
Resource profile	standard
Image source	inline
Daemon HTTP version	1.1
Ingress	attested-tunnel
Browser	Not selected
Maximum batch actions	50
Default action timeout	5000 ms
Maximum action timeout	300000 ms
Input rate limit	20 actions per second
Input backend	auto
Subprocess backend	isolated-asyncio
VNC mode	off

Resource values are requests, not caps. Modal can bill the request when it exceeds actual use.

Configuration ownership

The SDK passes orchestration fields directly to Modal. It maps daemon-owned settings to COMPUTER_USE_* environment variables.

The explicit image= argument to ComputerSandbox.create() replaces SDK image selection. The explicit expose_vnc= argument replaces config.expose_vnc.

Do not set SDK-generated proof or transport variables yourself. For example, the SDK computes whether a Modal Volume covers the artifact path.

Direct daemon settings

A directly launched daemon reads its process environment when it constructs DaemonSettings. There is no daemon config file.

Common groups include:

Group	Examples
Process and display	COMPUTER_USE_DAEMON_HOST, COMPUTER_USE_DAEMON_PORT, DISPLAY
Desktop behavior	COMPUTER_USE_BACKEND, COMPUTER_USE_INPUT_BACKEND, COMPUTER_USE_SUBPROCESS_BACKEND
Action limits	COMPUTER_USE_MAX_BATCH_ACTIONS, COMPUTER_USE_MAX_BATCH_DURATION_MS
Transport bounds	COMPUTER_USE_MAX_JSON_BODY_BYTES, COMPUTER_USE_MAX_WEBSOCKET_MESSAGE_BYTES
Authentication	COMPUTER_USE_LOCAL_TOKEN, COMPUTER_USE_TUNNEL_TOKEN
Storage	COMPUTER_USE_ARTIFACTS_DIR, COMPUTER_USE_RECORDINGS_DIR, COMPUTER_USE_TRACE_DIR
Budgets	COMPUTER_USE_MAX_ACTIONS, COMPUTER_USE_MAX_SCREENSHOTS, COMPUTER_USE_MAX_IDLE_SECONDS
Observability	COMPUTER_USE_OTEL_ENABLED

See the canonical configuration guide for the complete v1.1.0 environment list and bounds.

Secret handling

Treat these values as secrets:

• Bearer and tunnel tokens
• VNC passwords
• Daemon and noVNC URLs
• Browser startup URLs

Do not commit them. Do not include them in logs. Keep query credentials disabled.