feat: support service type externalName (#464)

pkg/dns/dns.go

@@ -39,6 +39,8 @@ type Config struct {
 	Hosts []Entry
 	Lock  *sync.Mutex
 
+	HowToGetExternalName func(name string) (string, error)
+
 	// only set it on linux
 	OSConfigurator dns.OSConfigurator
 }
@@ -278,10 +280,19 @@ func (c *Config) generateAppendHosts(serviceList []v12.Service, hosts []Entry) [
 		if strings.EqualFold(service.Name, ServiceKubernetes) {
 			continue
 		}
-		if net.ParseIP(service.Spec.ClusterIP) == nil {
+		var ip net.IP
+		if service.Spec.ClusterIP != "" {
+			ip = net.ParseIP(service.Spec.ClusterIP)
+		}
+		if service.Spec.ExternalName != "" {
+			name, _ := c.HowToGetExternalName(service.Spec.ExternalName)
+			ip = net.ParseIP(name)
+		}
+		if ip == nil {
 			continue
 		}
-		var e = Entry{IP: service.Spec.ClusterIP, Domain: service.Name}
+
+		var e = Entry{IP: ip.String(), Domain: service.Name}
 		if !sets.New[Entry]().Insert(entryList...).Has(e) {
 			entryList = append([]Entry{e}, entryList...)
 		}

pkg/handler/connect.go

@@ -622,6 +622,22 @@ func (c *ConnectOptions) setupDNS(ctx context.Context) error {
 		TunName:  c.tunName,
 		Hosts:    c.extraHost,
 		Lock:     c.Lock,
+		HowToGetExternalName: func(domain string) (string, error) {
+			podList, err := c.GetRunningPodList(ctx)
+			if err != nil {
+				return "", err
+			}
+			pod := podList[0]
+			return util.Shell(
+				ctx,
+				c.clientset,
+				c.config,
+				pod.GetName(),
+				config.ContainerSidecarVPN,
+				c.Namespace,
+				[]string{"dig", "+short", domain},
+			)
+		},
 	}
 	log.Debugf("Setup DNS...")
 	if err = c.dnsConfig.SetupDNS(ctx); err != nil {