ssl - Apache mod_proxy: forward secure websocket to non-secure

The websocket library I rely on (PHP-Websockets) does not yet support secure sockets (wss). My website is served over https though, so I cannot use insecure ws connections.

I'm trying to use Apache's mod_proxy to forward the secure request that comes from the browser on to the client.

Javascript

var ws = new Websocket('wss://example.com/_ws_/');

Apache VirtualHosts

ProxyPass        "/_ws_/" "ws://127.0.0.1:8080/"
ProxyPassReverse "/_ws_/" "ws://127.0.0.1:8080/"
# I've also tried "/_ws_/" "ws://example.com:8080/"  Same error below

Upon trying to connect, the browser receives a 500 Server Error. The logs show:

No protocol handler was valid for the URL /_ws_/. If you are using a DSO version of mod_proxy, make sure the proxy submodules are included in the configuration using LoadModule.

I've confirmed that if I remove the proxy rules, stop redirecting users to https and try to connect to insecure sockets from the browser: new Websocket('ws://example.com/'), things work just fine.

My loaded Apache modules include mod_ssl.c, mod_proxy.c and mod_proxy_http.c

Apache 2.4

Answer

To get things to work, I also needed to load mod_proxy_wstunnel

Once I did, this ruleset got things working: (in the VirtualHost of the domain that receives and proxies the websocket request)

    ProxyPass "/_ws_/" "ws://127.0.0.1:8080/"
    ProxyPassReverse "/_ws_/" "ws://127.0.0.1:8080/"

The browser can then contact the backend WS server through the HTTPS port:

var ws = new Websocket('wss://example.com/_ws_/');