# Charm configuration The charm declares one application-specific option: `hostname` : Type: string
Default: `gopkg.in`
Value passed to the workload as `APP_HOSTNAME`. It controls the hostname rendered in package links and `go-import` metadata. To change it and verify the result, follow [How to configure hostname](https://canonical.com/juju/docs/gopkg-charm/latest/how-to/configure-hostname-and-check-go-import/index.html.md#configure-hostname-and-check-go-import). Running `juju config gopkg-k8s` also lists the options that the Go framework extension adds when the charm is packed: `app-port`, `app-secret-key`, `app-secret-key-id`, `metrics-port`, and `metrics-path`. The observability options are described in [Integrations](https://canonical.com/juju/docs/gopkg-charm/latest/reference/integrations/index.html.md#integrations), and [charmcraft.yaml > config > options](https://canonical.com/juju/docs/charmcraft/4/reference/extensions/go-framework-extension/#go-framework-extension-config-options) documents the extension’s full set. Ingress routing is configured on the `nginx-ingress-integrator` charm, not on `gopkg-k8s`. See [How to configure ingress](https://canonical.com/juju/docs/gopkg-charm/latest/how-to/configure-ingress/index.html.md#configure-ingress) for the settings this deployment uses and the [NGINX ingress integrator configuration reference](https://charmhub.io/nginx-ingress-integrator/configurations) for every option.