Apache Module mod_proxy_wstunnel

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Description:	Websockets support module for `mod_proxy`
Status:	Extension
Module Identifier:	proxy_wstunnel_module
Source File:	mod_proxy_wstunnel.c
Compatibility:	Available in httpd 2.4.5 and later

Summary

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/"

Proxying both HTTP and websockets at the same time, with a specific set of URL's being websocket-only, can be done by specifying the websockets ProxyPass directive before the HTTP directive:

ProxyPassMatch ^/(myApp/ws)$  ws://backend.example.com:9080/$1
ProxyPass / http://backend.example.com:9080/

Proxying both HTTP and websockets at the same time, where the websockets URL's are not websocket-only or not known in advance can be done by using the RewriteRule directive to configure the websockets proxying:

ProxyPass / http://example.com:9080/
RewriteEngine on
RewriteCond %{HTTP:Upgrade} websocket [NC]
RewriteCond %{HTTP:Connection} upgrade [NC]
RewriteRule ^/?(.*) "ws://example.com:9080/$1" [P,L]

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

Bugfix checklist

ProxyWebsocketFallbackToProxyHttp Directive

Description:	Instructs this module to let `mod_proxy_http` handle the request
Syntax:	`ProxyWebsocketFallbackToProxyHttp On\|Off`
Default:	`ProxyWebsocketFallbackToProxyHttp On`
Context:	server config, virtual host
Status:	Extension
Module:	mod_proxy_wstunnel
Compatibility:	Available in httpd 2.4.48 and later

Since httpd 2.4.47, mod_proxy_http can handle WebSocket upgrading and tunneling in accordance to RFC 7230, this directive controls whether mod_proxy_wstunnel should hand over to mod_proxy_http to this, which is the case by default.

Setting to Off lets mod_proxy_wstunnel handle WebSocket requests as in httpd 2.4.46 and earlier.

ProxyWebsocketIdleTimeout Directive ¶

Description:	Sets the maximum amount of time to wait for data on the websockets tunnel
Syntax:	`ProxyWebsocketIdleTimeout num[ms]`
Default:	`ProxyWebsocketIdleTimeout 0`
Context:	server config, virtual host
Status:	Extension
Module:	mod_proxy_wstunnel

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.