Using a more modern and lightweight way for dealing with obsolete combos of OSs and application versions.
Credits/bibliography
I've been following Caddyserver's official site guidance here
Installing Caddy
ferdi@fsmntest0:~$ sudo apt update
ferdi@fsmntest0:~$ sudo apt upgrade -y
ferdi@fsmntest0:~$ sudo apt install -y debian-keyring debian-archive-keyring apt-transport-https
ferdi@fsmntest0:~$ curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/gpg.key' | sudo gpg --dearmor -o /usr/share/keyrings/caddy-stable-archive-keyring.gpg
ferdi@fsmntest0:~$ curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/debian.deb.txt' | sudo tee /etc/apt/sources.list.d/caddy-stable.list
# Source: Caddy
# Site: https://github.com/caddyserver/caddy
# Repository: Caddy / stable
# Description: Fast, multi-platform web server with automatic HTTPS
deb [signed-by=/usr/share/keyrings/caddy-stable-archive-keyring.gpg] https://dl.cloudsmith.io/public/caddy/stable/deb/debian any-version main
deb-src [signed-by=/usr/share/keyrings/caddy-stable-archive-keyring.gpg] https://dl.cloudsmith.io/public/caddy/stable/deb/debian any-version main
ferdi@fsmntest0:~$ sudo apt update
ferdi@fsmntest0:~$ sudo apt install caddy
Testing Caddy reverse proxying from command line
You have to stop the running daemon first; after that, it's a very intuitive command line.
ferdi@fsmntest0:~ $ sudo systemctl stop caddy
ferdi@fsmntest0:~ $ sudo caddy reverse-proxy \
> --from newsite.fsmn.xyz \
> --to https://blog.fsmn.xyz \
> --change-host-header
2022/11/17 09:01:52.330 WARN admin admin endpoint disabled
2022/11/17 09:01:52.330 INFO http server is listening only on the HTTPS port but has no TLS connection policies; adding one to enable TLS {"server_name": "proxy", "https_port": 443}
2022/11/17 09:01:52.330 INFO http enabling automatic HTTP->HTTPS redirects {"server_name": "proxy"}
2022/11/17 09:01:52.330 INFO tls.cache.maintenance started background certificate maintenance {"cache": "0xc000688bd0"}
2022/11/17 09:01:52.330 INFO http enabling HTTP/3 listener {"addr": ":443"}
2022/11/17 09:01:52.330 INFO tls cleaning storage unit {"description": "FileStorage:/root/.local/share/caddy"}
2022/11/17 09:01:52.330 INFO failed to sufficiently increase receive buffer size (was: 208 kiB, wanted: 2048 kiB, got: 416 kiB). See https://github.com/lucas-clemente/quic-go/wiki/UDP-Receive-Buffer-Size for details.
2022/11/17 09:01:52.330 INFO http.log server running {"name": "proxy", "protocols": ["h1", "h2", "h3"]}
2022/11/17 09:01:52.330 INFO http.log server running {"name": "remaining_auto_https_redirects", "protocols": ["h1", "h2", "h3"]}
2022/11/17 09:01:52.330 INFO http enabling automatic TLS certificate management {"domains": ["newsite.fsmn.xyz"]}
2022/11/17 09:01:52.331 INFO tls finished cleaning storage units
Caddy proxying https://newsite.fsmn.xyz -> blog.fsmn.xyz:443
Et voilà! HTTPS certificate requested to Let's Encrypt by Caddy on the fly! But there's an INFO message suggesting some system/kernel tuning, namely this one
ferdi@fsmntest0:/etc/caddy$ sudo sysctl -w net.core.rmem_max=2500000
net.core.rmem_max = 2500000
(of course you'll have to set it permanently). Subsequent caddy run with same parameters doesn't show this hint anymore.
How to convert this command in a Caddyfile suitable to systemd daemon?
Thanks to Markus Dosch for his blog article here
https://www.markusdosch.com/2022/05/caddy-web-server-why-use-it-how-to-use-it/
I've set up the main /etc/caddy/Caddyfile and the directory structure reminiscent of Apache's own /etc/caddy/sites-available.
The main Caddyfile contains now global options like my own email address, and an import directive.
root@fsmntest0:/etc/caddy/sites-enabled# cat /etc/caddy/Caddyfile
{
email info@fsimonetti.info
}
import /etc/caddy/sites-enabled/*.caddy
My revproxy.caddy (inside sites-enabled subdir) is here:
newsite.fsimonetti.info {
log {
output file /var/log/caddy/blog-access.log
}
reverse_proxy {
to https://blog.fsimonetti.info
header_up Host {upstream_hostport}
}
}
The most important directive here is the header_up that, according to official documentation found here
https://caddyserver.com/docs/caddyfile/directives/reverse_proxy#https
Enables us to rewrite the Host header of the request going to the upstream (backend for other reverse proxies out there) with its own FQDN as declared in to directive above.