cmd/kgctl: add output options for showconf

This commit adds several output options to the `showconf` command of the
`kgctl` binary:
* `--as-peer`: this can be used to generate a peer configuration, which
can be used to configure the selected resource as a peer of another
WireGuard interface
* `--output`: this can be used to select the desired output format of
the peer resource, available options are: WireGuard, YAML, and JSON.

pkg/k8s/apis/kilo/v1alpha1/register.go

@@ -31,7 +31,7 @@ var (
 const GroupName = "kilo.squat.ai"
 
 // SchemeGroupVersion is the group version used to register these objects.
-var SchemeGroupVersion = schema.GroupVersion{Group: GroupName, Version: "v1alpha1"}
+var SchemeGroupVersion = schema.GroupVersion{Group: GroupName, Version: Version}
 
 // Resource takes an unqualified resource and returns a Group-qualified GroupResource.
 func Resource(resource string) schema.GroupResource {

pkg/k8s/apis/kilo/v1alpha1/types.go

@@ -21,15 +21,23 @@ import (
 	"net"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 )
 
 const (
+	// Version is the version of this API.
+	Version = "v1alpha1"
 	// PeerKind is the API kind for the peer resource.
 	PeerKind = "Peer"
 	// PeerPlural is the plural name for the peer resource.
 	PeerPlural = "peers"
 )
 
+var (
+	// PeerGVK is the GroupVersionKind for Peers.
+	PeerGVK = schema.GroupVersionKind{Group: GroupName, Version: Version, Kind: PeerKind}
+)
+
 // PeerShortNames are convenient shortnames for the peer resource.
 var PeerShortNames = []string{"peer"}
 

pkg/mesh/topology.go

@@ -338,6 +338,25 @@ func (t *Topology) Conf() *wireguard.Conf {
 	return c
 }
 
+// AsPeer generates the WireGuard peer configuration for the local location of the given Topology.
+// This configuration can be used to configure this location as a peer of another WireGuard interface.
+func (t *Topology) AsPeer() *wireguard.Peer {
+	for _, s := range t.segments {
+		if s.location != t.location {
+			continue
+		}
+		return &wireguard.Peer{
+			AllowedIPs: s.allowedIPs,
+			Endpoint: &wireguard.Endpoint{
+				IP:   s.endpoint,
+				Port: uint32(t.port),
+			},
+			PublicKey: s.key,
+		}
+	}
+	return nil
+}
+
 // PeerConf generates a WireGuard configuration file for a given peer in a Topology.
 func (t *Topology) PeerConf(name string) *wireguard.Conf {
 	c := &wireguard.Conf{}