Settings

Use the following options to configure Uvicorn, when running from the command line.

If you're running using programmatically, using uvicorn.run(...), then use equivalent keyword arguments, eg. uvicorn.run("example:app", port=5000, reload=True, access_log=False).

Application

• APP - The ASGI application to run, in the format "<module>:<attribute>".

Socket Binding

• --host <str> - Bind socket to this host. Use --host 0.0.0.0 to make the application available on your local network. Default: '127.0.0.1'.
• --port <int> - Bind to a socket with this port. Default: 8000.
• --uds <str> - Bind to a UNIX domain socket. Useful if you want to run Uvicorn behind a reverse proxy.
• --fd <int> - Bind to socket from this file descriptor. Useful if you want to run Uvicorn within a process manager.

Development

• --reload - Enable auto-reload.
• --reload-dir <path> - Specify which directories to watch for python file changes. May be used multiple times. If unused, then by default all directories in current directory will be watched.

By default Uvicorn uses simple changes detection strategy that compares python files modification times few times a second. If this approach doesn't work for your project (eg. because of its complexity), you can install Uvicorn with optional watchgod dependency to use filesystem events instead:

$ pip install uvicorn[watchgodreload]

Production

• --workers <int> - Use multiple worker processes. Defaults to the value of the $WEB_CONCURRENCY environment variable.

Logging

• --log-config <path> - Logging configuration file.
• --log-level <str> - Set the log level. Options: 'critical', 'error', 'warning', 'info', 'debug', 'trace'. Default: 'info'.
• --no-access-log - Disable access log only, without changing log level.
• --use-colors / --no-use-colors - Enable / disable colorized formatting of the log records, in case this is not set it will be auto-detected.

Implementation

• --loop <str> - Set the event loop implementation. The uvloop implementation provides greater performance, but is not compatible with Windows or PyPy. But you can use IOCP in windows. Options: 'auto', 'asyncio', 'uvloop', 'iocp'. Default: 'auto'.
• --http <str> - Set the HTTP protocol implementation. The httptools implementation provides greater performance, but it not compatible with PyPy, and requires compilation on Windows. Options: 'auto', 'h11', 'httptools'. Default: 'auto'.
• --ws <str> - Set the WebSockets protocol implementation. Either of the websockets and wsproto packages are supported. Use 'none' to deny all websocket requests. Options: 'auto', 'none', 'websockets', 'wsproto'. Default: 'auto'.
• --lifespan <str> - Set the Lifespan protocol implementation. Options: 'auto', 'on', 'off'. Default: 'auto'.

Application Interface

• --interface - Select ASGI3, ASGI2, or WSGI as the application interface. Note that WSGI mode always disables WebSocket support, as it is not supported by the WSGI interface. Options: 'auto', 'asgi3', 'asgi2', 'wsgi'. Default: 'auto'.

HTTP

• --root-path <str> - Set the ASGI root_path for applications submounted below a given URL path.
• --proxy-headers / --no-proxy-headers - Enable/Disable X-Forwarded-Proto, X-Forwarded-For, X-Forwarded-Port to populate remote address info. Defaults to enabled, but is restricted to only trusting connecting IPs in the forwarded-allow-ips configuration.
• --forwarded-allow-ips Comma separated list of IPs to trust with proxy headers. Defaults to the `$FORWARDED_ALLOW_IPS environment variable if available, or '127.0.0.1'. A wildcard '*' means always trust.

HTTPS

• --ssl-keyfile <path> - SSL key file
• --ssl-certfile <path> - SSL certificate file
• --ssl-version <int> - SSL version to use (see stdlib ssl module's)
• --ssl-cert-reqs <int> - Whether client certificate is required (see stdlib ssl module's)
• --ssl-ca-certs <str> - CA certificates file
• --ssl-ciphers <str> - Ciphers to use (see stdlib ssl module's)

Resource Limits

• --limit-concurrency <int> - Maximum number of concurrent connections or tasks to allow, before issuing HTTP 503 responses. Useful for ensuring known memory usage patterns even under over-resourced loads.
• --limit-max-requests <int> - Maximum number of requests to service before terminating the process. Useful when running together with a process manager, for preventing memory leaks from impacting long-running processes.
• --backlog <int> - Maximum number of connections to hold in backlog. Relevant for heavy incoming traffic.

Timeouts

• --timeout-keep-alive <int> - Close Keep-Alive connections if no new data is received within this timeout. Default: 5.