mod_proxy_wstunnel
Websockets support module for mod_proxy
Extension
mod_proxy_wstunnel.c
proxy_wstunnel_module
Available in httpd 2.4.5 and later

This module requires the service of mod_proxy. It provides support for the tunnelling of web socket connections to a backend websockets server. The connection is automatically upgraded to a websocket connection:

# HTTP Response

Upgrade: WebSocket Connection: Upgrade

Proxying requests to a websockets server like `echo.websocket.org` can be done using the ProxyPass directive:

ProxyPass "/ws2/" "ws://echo.websocket.org/" ProxyPass "/wss2/" "wss://echo.websocket.org/"

Load balancing for multiple backends can be achieved using mod_proxy_balancer.

In fact the module can be used to upgrade to other protocols, you can set the `upgrade` parameter in the ProxyPass directive to allow the module to accept other protocol. NONE means you bypass the check for the header but still upgrade to WebSocket. ANY means that `Upgrade` will read in the request headers and use in the response `Upgrade`

mod_proxy
ProxyWebsocketAsync
Instructs this module to try to create an asynchronous tunnel
ProxyWebsocketAsync ON|OFF
server config
virtual host

This directive instructs the server to try to create an asynchronous tunnel. If the current MPM does not support the necessary features, a synchronous tunnel is used.

# Note

Async support is experimental and subject to change.

ProxyWebsocketIdleTimeout
Sets the maximum amount of time to wait for data on the websockets tunnel
ProxyWebsocketIdleTimeout num[ms]
ProxyWebsocketIdleTimeout 0
server config
virtual host

This directive imposes a maximum amount of time for the tunnel to be left open while idle. The timeout is considered in seconds by default, but it is possible to increase the time resolution to milliseconds adding the ms suffix.

ProxyWebsocketAsyncDelay
Sets the amount of time the tunnel waits synchronously for data
ProxyWebsocketAsyncDelay num[ms]
ProxyWebsocketAsyncDelay 0
server config
virtual host

If ProxyWebsocketAsync is enabled, this directive controls how long the server synchronously waits for more data. The timeout is considered in seconds by default, but it is possible to increase the time resolution to milliseconds adding the ms suffix.

# Note

Async support is experimental and subject to change.