m/n/c/metrics: add node name to discovery labels

This allows for identifying the node directly without taking a detour
via its IP address.

Change-Id: Ia36ba52385292264a42f451ce2c63e9a6c76fdb6
Reviewed-on: https://review.monogon.dev/c/monogon/+/2336
Tested-by: Jenkins CI
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
diff --git a/metropolis/node/core/metrics/discovery.go b/metropolis/node/core/metrics/discovery.go
index d5a992b..ff3fcf1 100644
--- a/metropolis/node/core/metrics/discovery.go
+++ b/metropolis/node/core/metrics/discovery.go
@@ -77,6 +77,7 @@
 					"__meta_metropolis_role_kubernetes_worker":     fmt.Sprintf("%t", new.Roles.KubernetesWorker != nil),
 					"__meta_metropolis_role_kubernetes_controller": fmt.Sprintf("%t", new.Roles.KubernetesController != nil),
 					"__meta_metropolis_role_consensus_member":      fmt.Sprintf("%t", new.Roles.ConsensusMember != nil),
+					"__meta_metropolis_node":                       new.Id,
 				},
 			})
 			return nil