Configure placement, cost, and limits - Modal Computer Use

Use ComputerConfig when the SDK creates a Sandbox. A directly launched daemon reads its process environment.

Build one inspectable configuration

from modal_computer_use import ComputerConfig

config = ComputerConfig(
    ingress="attested-tunnel",
    runtime={
        "modal_environment": "main",
        "modal_region": "us-west-2",
        "timeout_seconds": 900,
        "readiness_timeout_seconds": 120,
    },
    resources={"profile": "browser", "cpu": 1.0, "memory_mib": 2048},
    image={"source": "inline"},
    browser={"kind": "chromium", "prewarm": False},
    actions={
        "input_rate_limit_per_sec": 100,
        "input_rate_limit_burst": 400,
        "screenshot_capture_source": "mss",
    },
)

print(config.resolved_cost_and_placement())

The example region and resources are application choices. Measure your workload before changing them.

Keep cost-bearing choices explicit

Choice	Default policy
Region	No universal SDK region
CPU and memory	No universal SDK values
Image	Inline recipe
Function minimum containers	Application setting, zero in the primary example
Sandbox warm pool	Off
Browser prewarm	Explicit application choice

Configure screenshot capture

SDK value	Daemon value	Behavior
`mss`	`COMPUTER_USE_SCREENSHOT_CAPTURE_SOURCE=mss`	Production default
`auto`	`...=auto`	Probe X11-SHM, then allow ordinary MSS fallback
`x11-shm`	`...=x11-shm`	Require the optional native source

Explicit X11-SHM requires a managed Image containing the extension. A display reply timeout fails closed. See screenshots and recordings.

Configure weighted input admission

The defaults use 100 normalized input-work tokens per second and a 400-token burst. The daemon reserves a complete recursive batch before mutation. Run the same-runtime capacity gate before you raise both values. CPU and memory alone cannot select a reliable limit.

Protect secrets

Treat bearer tokens, noVNC URLs and passwords, browser startup URLs, typed text, clipboard text, screenshot bytes, and artifact bytes as secrets. Configuration validation hides rejected values. Read the configuration reference for every field and environment variable.