Fast Hot Reload for FastAPI

This package provides client-side hot reload functionality for FastAPI applications.

Installation

pip install fast-hot-reload

Usage

Import FastHotReload and instantiate it, passing your FastAPI app instance:

from fastapi import FastAPI
from fast_hot_reload import FastHotReload

app = FastAPI()

# Basic usage
FastHotReload(app)

# If not connecting, try alternate config:
FastHotReload(app=app, use_alternate_config=True)

# For non-standard, proxies or remote dev servers
FastHotReload(
    app,
    ws_host_override="custom_host",
    ws_port_override=8000,
)

# Note: use_alternate_config is incompatible with host/port overrides

Now when you run your app with uvicorn --reload, changes will trigger an automatic browser reload.

Options

• on_reload: Callback invoked when a reload is triggered
• use_alternate_config: Try this if reload is not working as expected
• ws_host_override: Websocket host if using a proxy
• ws_port_override: Websocket port if using a custom port

Advanced Usage

The FastHotReload constructor accepts serveral advanced keyword arguments to further customize event language: Here is a section on the advanced kwargs usage:

FastHotReload(
  app,

  # Custom messaging
  ws_message_prefix="[Hot Reload]",
  ws_connected_message="Connected!",
  ws_reconnect_message="Reconnecting in ${reconnectInterval} seconds...",
  
  # Performance
  _ws_reconnect_interval=5, # seconds
)

• ws_message_prefix - Prefix for websocket messages
• ws_connected_message - Message on initial connect
• ws_reconnect_message - Message on reconnect. ${reconnectInterval} is dynamically replaced.
• _ws_reconnect_interval - Interval in sec between reconnect attempts

These can be used to integrate with a non-standard dev server setup.

How it works

• Implements a FastAPI middleware
• Opens a websocket connection to the dev server
• Listens for file change events
• Triggers browser reload when changes are detected

Contributing

Contributions welcome! Please open issues and/or PRs.

License

MIT