cluster: introduce NodeID and ZoneID types

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/cluster/zones.go

@@ -19,7 +19,7 @@ type Zone struct {
 	zones  *Cluster
 	logger `json:"-" yaml:"-"`
 
-	ID      int
+	ID      ZoneID
 	Name    string
 	Regions []string `json:",omitempty" yaml:",omitempty"`
 
@@ -31,7 +31,7 @@ func (z *Zone) String() string {
 }
 
 // SetGateway configures a machine to be the zone's ring0 gateway
-func (z *Zone) SetGateway(gatewayID int, enabled bool) error {
+func (z *Zone) SetGateway(gatewayID NodeID, enabled bool) error {
 	var err error
 	var found bool
 
@@ -56,8 +56,8 @@ func (z *Zone) SetGateway(gatewayID int, enabled bool) error {
 }
 
 // GatewayIDs returns the list of IDs of machines that act as ring0 gateways
-func (z *Zone) GatewayIDs() ([]int, int) {
-	var out []int
+func (z *Zone) GatewayIDs() ([]NodeID, int) {
+	var out []NodeID
 	z.ForEachMachine(func(p *Machine) bool {
 		if p.IsGateway() {
 			out = append(out, p.ID)