Check server's public IP

1. The problem I’m having:

My google-fu is failing me (thanks AI), I am trying to find out if there is a way within Caddy to automatically update my public IP address (it’s incredibly stable, but I’m not paying for a static IP) for an IP whitelist on some of my services that I don’t want exposed to the internet, but do want valid certs for (purely to get rid of the cert nag).

2. Error messages and/or full log output:

No relevant logs

3. Caddy version:

v2.11.3 h1:/vFbdjcs2DtzcWTIxHybf5R5TspYFFThlZffChyBFHg=

4. How I installed and ran Caddy:

a. System environment:

N/A

b. Command:

systemctl enable caddy
systemctl start caddy

c. Service/unit/compose file:

d. My complete Caddy config:

nas.example.com {
  @allowed client_ip 192.168.0.0/21 my.public.ip.address # <--Can this be a variable that is updated automatically?
  handle @allowed {
    reverse_proxy 192.168.x.x:80
  }
}

5. Links to relevant resources: