Exposing metrics

[bygui86]

Hi everybody,

first of all thanks for this amazing tool, it's super useful!

It would be a really good idea to expose some metrics :) maybe not only Golang default ones, but also something custom like:

• kubeip_ip_address_usable_total to show how many reserved IP addresses were found and are usable by KubeIP
• kubeip_ip_address_assigned_total to show how many of the available IP addresses are currently in use
• kubeip_ip_address_available_total to show how many of the available IP addresses are still available (not in use)
• kubeip_ip_address_assigned to show if and which IP address was assigned to the node KubeIP is running on
  • possible values:
    • 0 if an IP address was successfully assigned
    • 1 otherwise
  • labels:
    • k8s_node
    • ip_address_name
    • ip_address