Use default address family when adding kubernetes service address to SAN list

pkg/cli/server/server.go

@@ -204,18 +204,17 @@ func run(app *cli.Context, cfg *cmds.Server, leaderControllers server.CustomCont
 	}
 
 	if serverConfig.ControlConfig.PrivateIP == "" && len(cmds.AgentConfig.NodeIP) != 0 {
-		// ignoring the error here is fine since etcd will fall back to the interface's IPv4 address
-		serverConfig.ControlConfig.PrivateIP, _, _ = util.GetFirstString(cmds.AgentConfig.NodeIP)
+		serverConfig.ControlConfig.PrivateIP = util.GetFirstValidIPString(cmds.AgentConfig.NodeIP)
 	}
 
 	// if not set, try setting advertise-ip from agent node-external-ip
 	if serverConfig.ControlConfig.AdvertiseIP == "" && len(cmds.AgentConfig.NodeExternalIP) != 0 {
-		serverConfig.ControlConfig.AdvertiseIP, _, _ = util.GetFirstString(cmds.AgentConfig.NodeExternalIP)
+		serverConfig.ControlConfig.AdvertiseIP = util.GetFirstValidIPString(cmds.AgentConfig.NodeExternalIP)
 	}
 
 	// if not set, try setting advertise-ip from agent node-ip
 	if serverConfig.ControlConfig.AdvertiseIP == "" && len(cmds.AgentConfig.NodeIP) != 0 {
-		serverConfig.ControlConfig.AdvertiseIP, _, _ = util.GetFirstString(cmds.AgentConfig.NodeIP)
+		serverConfig.ControlConfig.AdvertiseIP = util.GetFirstValidIPString(cmds.AgentConfig.NodeIP)
 	}
 
 	// if we ended up with any advertise-ips, ensure they're added to the SAN list;
@@ -297,7 +296,7 @@ func run(app *cli.Context, cfg *cmds.Server, leaderControllers server.CustomCont
 	}
 
 	// the apiserver service does not yet support dual-stack operation
-	_, apiServerServiceIP, err := controlplane.ServiceIPRange(*serverConfig.ControlConfig.ServiceIPRange)
+	_, apiServerServiceIP, err := controlplane.ServiceIPRange(*serverConfig.ControlConfig.ServiceIPRanges[0])
 	if err != nil {
 		return err
 	}

pkg/util/net.go

@@ -189,6 +189,19 @@ func ParseStringSliceToIPs(s cli.StringSlice) ([]net.IP, error) {
 	return ips, nil
 }
 
+// GetFirstValidIPString returns the first valid address from a list of IP address strings,
+// without preference for IP family. If no address are found, an empty string is returned.
+func GetFirstValidIPString(s cli.StringSlice) string {
+	for _, unparsedIP := range s {
+		for _, v := range strings.Split(unparsedIP, ",") {
+			if ip := net.ParseIP(v); ip != nil {
+				return v
+			}
+		}
+	}
+	return ""
+}
+
 // GetFirstIP returns the first IPv4 address from the list of IP addresses.
 // If no IPv4 addresses are found, returns the first IPv6 address
 // if neither of IPv4 or IPv6 are found an error is raised.