Writing plugins for Caddy is so easy that it's generally not necessary to have scripting built-in. You can just build yourself a new binary with a Go plugin just by using the "xcaddy" build tool. https://caddyserver.com/docs/extending-caddy

But yeah, it's still something at the back of our minds, and we were considering Starlark for this, but that hasn't really materialized because it's usually easier to just go with the plugin route.