Set the listen host and port#

This guide shows you how to set the host and TCP port your instance listens on for HTTP requests.

Prerequisites#

Step 1: set the listen address#

In your instance.yaml, set wsgi_listen to a host:port value:

default_context:
    wsgi_listen: localhost:8080

The default is localhost:8080, which accepts connections only from the local machine.

To accept connections from any network interface, bind to 0.0.0.0:

default_context:
    wsgi_listen: 0.0.0.0:8080

Important

When the instance runs behind a reverse proxy, bind to 127.0.0.1 so that only the proxy can reach it directly:

wsgi_listen: 127.0.0.1:8080

Step 2: enable a fast listen socket (optional)#

wsgi_fast_listen configures a second socket served by waitress-fastlisten. Install that package, then set the address:

default_context:
    wsgi_listen: 127.0.0.1:8080
    wsgi_fast_listen: 127.0.0.1:8081

Leave wsgi_fast_listen empty to disable the fast socket.

Verify#

After generating the instance, start it and confirm the bound address in the startup log:

runwsgi instance/etc/zope.ini

The log reports the host and port Waitress serves on.

Next steps#

  • Basic configuration – Full reference for wsgi_listen, wsgi_fast_listen, trusted proxies, and other WSGI server settings.

  • Sample configurations – Complete, copy-paste configurations for every backend.