How do I set up a reverse proxy in ISPConfig?

Question

Is it possible to set up a reverse proxy in ISPConfig?

I tried this setting on a subdomain, but I only receive a error 500.

The /var/www/influxdb2.*******.***/log/error.log says the following:

==> error.log <==
[Fri Jan 01 21:24:15.963158 2021] [proxy:warn] [pid 30333] [client ***.***.***.***:59356] AH01144: No protocol handler was valid for the URL /favicon.ico (scheme 'http'). If you are using a DSO version of mod_proxy, make sure the proxy submodules are included in the configuration using LoadModule., referer: https://influxdb2.*******.***/

Answer 1

For me, the proxy_http mod was missing.

Enable it via sudo a2enmod proxy_http and restart your apache with systemctl restart apache2 (thanks to https://serverfault.com/questions/773449/no-protocol-handler-valid-for-the-url-with-httpd-mod-proxy-balancer).

Also note that the "redirect type" setting sometimes seems to reset itself to "none" on saving (or at least does not display the correct value on loading the page as of ISPConfig 3.2.1). So double check that setting if something does not work.

For the "Domain" tab, settings are pretty straightforward. Just enter your domain and probably enable Let's Encrypt.

Note that this seems to use mod_rewrite for proxying. The Apache2 documentation on mod_rewrite states that better ProxyPass of mod_proxy should be used instead. So if anything breaks with some applications, this might be a starting point for further investigations (worked for me for reverse proxying to the HTTP endpoint of InfluxDB 2.0.3 at http://localhost:8086).