The NixOS caddy module already emits one global options block (for `email`)
and appends extraConfig after it. gebos-caddy also prepended its own keyless
`{ layer4 { ... } }` block, so the rendered Caddyfile had two keyless blocks
and caddy rejected it: "server block without any key is global configuration,
and if used, it must be first" -> caddy.service failed -> mqtt-ingest
activation exited 4 and deploy-rs rolled back.
Move the layer4 directive into services.caddy.globalConfig so it lands inside
the module's single global block. Verified the rendered Caddyfile for
mqtt-ingest; app-host (http-only) output is unchanged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Lars Nolden
08d9fc594e