Tip:

For my cloud vps with Caddy and several containers I just pointed Caddy at a simple Caddyfile /opt/caddy/Caddyfile that globally sets up some basic things (like tls config for Let’s encrypt with email address and such) followed by import sites-enabled/*

So every container gets a Caddyfile in /opt/caddy/sites-available/app.caddyfile (or wherever) and that one gets just linked to /opt/caddy/sites-enabled/.

Now it’s easy to change the config of an app and only that one app.