### Reverse proxy #### Introduction A reverse proxy is for example used to host 2 services on the same port. This is useful for us because we can use the same port for the websockets and the webserver. #### How to use a reverse proxy We are going to use `Apache2` as our reverse proxy. This is because it is easy to use and has a lot of documentation. It also hosts our webserver so it is easy to configure and we don't have to install another program. #### Additional modules We need to enable the `proxy` and `proxy_wstunnel` modules. These are used to proxy the websockets. You can install them with these commands on a Raspberry Pi. For other linux distributions its may be different. ```bash $ sudo a2enmod proxy $ sudo a2enmod proxy_wstunnel ``` #### Script The enabled apache2 config scripts are found in `/etc/apache2/conf-enabled/`. You can create a new file with the name of your service. For example `studyarea.conf`. ```apache DocumentRoot /home/pi/www/html/ # Enable proxying WebSockets ProxyPass /ws ws://localhost:8001/ # Enable proxying HTTP ProxyPass /ws http://localhost:8080/ ``` Because VirtualHost is listening on port 80, we can use the same port for the webserver and the websockets. The `ProxyPass` is used to proxy the websocket. The `/ws` is the path where the websockets are hosted. Its hosted on `localhost/ws` so it kinda creates a new subdomain for the websocket. The `localhost:8001` is the address of the websockets and the `localhost:8080` is the address of the webserver. `DocumentRoot` is the path where the files are for the website. ### Sources: * https://httpd.apache.org/docs/2.4/howto/reverse_proxy.html * https://www.serverlab.ca/tutorials/linux/web-servers-linux/how-to-reverse-proxy-websockets-with-apache-2-4/ * https://gist.github.com/mortenege/91ec6fe02dca6f736303a00f8cea2731 * https://www.jscape.com/blog/forward-proxy-vs-reverse-proxy#:~:text=While%20a%20forward%20proxy%20proxies,is%20providing%20file%20transfer%20services. * https://webmasters.stackexchange.com/questions/143106/functional-difference-between-proxypass-and-proxypassreverse-in-apache