Reverse proxy to a different host, many subdomains

[Singman33]

1. The problem I’m having:

To simplify my problem as much as possible, let’s consider that I have 3 VMs: one with Caddy (proxy.domain.lan) and two Apache servers (selmai.domain.lan & web.domain.lan).
“proxy” is the entry point of all my web traffic (80 / 443).
If I receive a request on the domain “selmai.fr”, I want it to be directed to “selmai.domain.local”
If I receive a request on the domain “asso.ericdelcamp.fr”, I want it to be directed to “web.domain.local:3000” (there will eventually be several sites hosted on this VM with each a different port.
Everything works fine with “selmai.fr” but I recently built this VM.
When I try to reach “asso.ericdelcamp.fr”, I always end up on the default Apache page and not on the site.

• Does “proxy” need to have certificates for itself?
• To get a certificate for “asso.ericdelcamp.fr”, I use certbot locally by cutting the port forwarding to the proxy and by modifying my apache config, the time to get a certificate. Is this the right one method?
• Why can’t I get anything other than the default Apache page? In my address bar, the URL “asso.ericdelcamp.fr” is transformed into “web.domain.local”.

2. Error messages and/or full log output:

Jan 17 21:42:21 proxy systemd[1]: Reloading caddy.service - Caddy...
Jan 17 21:42:21 proxy caddy[1048]: {"level":"info","ts":1737146541.240933,"msg":"using config from file","file":"/etc/caddy/Caddyfile"}
Jan 17 21:42:21 proxy caddy[1048]: {"level":"info","ts":1737146541.2426274,"msg":"adapted config to JSON","adapter":"caddyfile"}
Jan 17 21:42:21 proxy systemd[1]: Reloaded caddy.service - Caddy.

3. Caddy version:

2.9.1

4. How I installed and ran Caddy:

Install - Caddy Documentation

a. System environment:

Ubuntu 24.04.1
Selmai : Apache/2.4.58 (Ubuntu)
Web : Apache/2.4.58 (Ubuntu)

b. Command:

curl -v http://selmai.fr
* Host selmai.fr:80 was resolved.
* IPv6: (none)
* IPv4: 82.65.33.149
*   Trying 82.65.33.149:80...
* Connected to selmai.fr (82.65.33.149) port 80
> GET / HTTP/1.1
> Host: selmai.fr
> User-Agent: curl/8.9.1
> Accept: */*
>
< HTTP/1.1 308 Permanent Redirect
< Connection: close
< Location: https://selmai.fr/
< Server: Caddy
< Date: Fri, 17 Jan 2025 21:15:46 GMT
< Content-Length: 0
<
* we are done reading and this is set to close, stop send
* shutting down connection #0

curl -v http://asso.ericdelcamp.fr
* Host asso.ericdelcamp.fr:80 was resolved.
* IPv6: (none)
* IPv4: 82.65.33.149
*   Trying 82.65.33.149:80...
* Connected to asso.ericdelcamp.fr (82.65.33.149) port 80
> GET / HTTP/1.1
> Host: asso.ericdelcamp.fr
> User-Agent: curl/8.9.1
> Accept: */*
>
< HTTP/1.1 308 Permanent Redirect
< Connection: close
< Location: https://asso.ericdelcamp.fr/
< Server: Caddy
< Date: Fri, 17 Jan 2025 21:16:28 GMT
< Content-Length: 0
<
* we are done reading and this is set to close, stop send
* shutting down connection #0

c. Service/unit/compose file:

d. My complete Caddy config:

{
        debug
        log default {
                output file /var/log/caddy/caddy.log {
                        mode 600
                }
        }
}

selmai.fr {
        reverse_proxy selmai.domain.lan {
                header_up Host {upstream_hostport}
        }
        log {
                output file /var/log/caddy/selmai.log
                format transform `{request>headers>X-Forwarded-For>[0]:request>remote_ip} - {user_id} [{ts}] "{request>method} {request>uri} {request>proto}" {status} {size} "{request>headers>Referer>[0]}" "{request>headers>User-Agent>[0]}"` {
                        time_format "02/Jan/2006:15:04:05 -0700"
                }
        }
}

asso.ericdelcamp.fr {
        reverse_proxy web.domain.lan:3000 {
                header_up Host {upstream_hostport}
        }
        log {
                output file /var/log/caddy/asso.log
                format transform `{request>headers>X-Forwarded-For>[0]:request>remote_ip} - {user_id} [{ts}] "{request>method} {request>uri} {request>proto}" {status} {size} "{request>headers>Referer>[0]}" "{request>headers>User-Agent>[0]}"` {
                        time_format "02/Jan/2006:15:04:05 -0700"
                }
        }
}

e. Apache selmai.conf

<VirtualHost *:80>
      ServerName selmai.fr
      DocumentRoot /var/www/html

      <Directory /var/www/html/phpbb>
                Options FollowSymlinks
                AllowOverride All
                Require all granted
       </Directory>

        ErrorLog ${APACHE_LOG_DIR}/selmai_error.log
        CustomLog ${APACHE_LOG_DIR}/selmai_access.log combined

RewriteEngine on
RewriteCond %{SERVER_NAME} =selmai.fr
RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]
</VirtualHost>

f. Apache asso.conf

<VirtualHost *:3000>
        ServerName asso.ericdelcamp.fr

        DocumentRoot /var/www/dolibarr/htdocs/
        ErrorLog ${APACHE_LOG_DIR}/dolibarr_error.log
        CustomLog ${APACHE_LOG_DIR}/dolibarr_access.log combined

        <Directory /var/www/dolibarr/htdocs/>
                Require all granted
        </Directory>
</VirtualHost>

5. Links to relevant resources: