The serve command is used to preview a book by serving it over HTTP at localhost:3000 by default. Additionally it watches the book's directory for changes, rebuilding the book and refreshing clients for each change. A websocket connection is used to trigger the client-side refresh.

The serve command can take a directory as an argument to use as the book's root instead of the current working directory.

mdbook serve path/to/book

serve has four options: the HTTP port, the WebSocket port, the HTTP hostname to listen on, and the hostname for the browser to connect to for WebSockets.

For example: suppose you have an nginx server for SSL termination which has a public address of 192.168.1.100 on port 80 and proxied that to 127.0.0.1 on port 8000. To run use the nginx proxy do:

mdbook serve path/to/book -p 8000 -n 127.0.0.1 --websocket-hostname 192.168.1.100

If you were to want live reloading for this you would need to proxy the websocket calls through nginx as well from 192.168.1.100:<WS_PORT> to 127.0.0.1:<WS_PORT>. The -w flag allows for the websocket port to be configured.

When you use the --open (-o) flag, mdbook will open the book in your your default web browser after starting the server.

The --dest-dir (-d) option allows you to change the output directory for the book. If not specified it will default to the value of the build.build-dir key in book.toml, or to ./book relative to the book's root directory.

Note: The serve command is for testing, and is not intended to be a complete HTTP server for a website.