let utils.ParseHost return err when errors happen

docker/docker.go

@@ -46,7 +46,12 @@ func main() {
 		flHosts = flHosts[1:] //trick to display a nice default value in the usage
 	}
 	for i, flHost := range flHosts {
-		flHosts[i] = utils.ParseHost(docker.DEFAULTHTTPHOST, docker.DEFAULTHTTPPORT, flHost)
+		host, err := utils.ParseHost(docker.DEFAULTHTTPHOST, docker.DEFAULTHTTPPORT, flHost)
+		if err == nil {
+			flHosts[i] = host
+		} else {
+			log.Fatal(err)
+		}
 	}
 
 	if *bridgeName != "" {

utils/utils.go

@@ -10,7 +10,6 @@ import (
 	"index/suffixarray"
 	"io"
 	"io/ioutil"
-	"log"
 	"net/http"
 	"os"
 	"os/exec"
@@ -818,17 +817,17 @@ func StripComments(input []byte, commentMarker []byte) []byte {
 	return output
 }
 
-func ParseHost(host string, port int, addr string) string {
+func ParseHost(host string, port int, addr string) (string, error) {
 	var proto string
 	switch {
 	case strings.HasPrefix(addr, "unix://"):
-		return addr
+		return addr, nil
 	case strings.HasPrefix(addr, "tcp://"):
 		proto = "tcp"
 		addr = strings.TrimPrefix(addr, "tcp://")
 	default:
 		if strings.Contains(addr, "://") {
-			log.Fatal("Invalid bind address proto")
+			return "", fmt.Errorf("Invalid bind address protocol: %s", addr)
 		}
 		proto = "tcp"
 	}
@@ -836,7 +835,7 @@ func ParseHost(host string, port int, addr string) string {
 	if strings.Contains(addr, ":") {
 		hostParts := strings.Split(addr, ":")
 		if len(hostParts) != 2 {
-			log.Fatal("Invalid bind address format.")
+			return "", fmt.Errorf("Invalid bind address format: %s", addr)
 		}
 		if hostParts[0] != "" {
 			host = hostParts[0]
@@ -847,7 +846,7 @@ func ParseHost(host string, port int, addr string) string {
 	} else {
 		host = addr
 	}
-	return fmt.Sprintf("%s://%s:%d", proto, host, port)
+	return fmt.Sprintf("%s://%s:%d", proto, host, port), nil
 }
 
 func GetReleaseVersion() string {

utils/utils_test.go

@@ -266,21 +266,24 @@ func TestHumanSize(t *testing.T) {
 }
 
 func TestParseHost(t *testing.T) {
-	if addr := ParseHost("127.0.0.1", 4243, "0.0.0.0"); addr != "tcp://0.0.0.0:4243" {
+	if addr, err := ParseHost("127.0.0.1", 4243, "0.0.0.0"); err != nil || addr != "tcp://0.0.0.0:4243" {
 		t.Errorf("0.0.0.0 -> expected tcp://0.0.0.0:4243, got %s", addr)
 	}
-	if addr := ParseHost("127.0.0.1", 4243, "0.0.0.1:5555"); addr != "tcp://0.0.0.1:5555" {
+	if addr, err := ParseHost("127.0.0.1", 4243, "0.0.0.1:5555"); err != nil || addr != "tcp://0.0.0.1:5555" {
 		t.Errorf("0.0.0.1:5555 -> expected tcp://0.0.0.1:5555, got %s", addr)
 	}
-	if addr := ParseHost("127.0.0.1", 4243, ":6666"); addr != "tcp://127.0.0.1:6666" {
+	if addr, err := ParseHost("127.0.0.1", 4243, ":6666"); err != nil || addr != "tcp://127.0.0.1:6666" {
 		t.Errorf(":6666 -> expected tcp://127.0.0.1:6666, got %s", addr)
 	}
-	if addr := ParseHost("127.0.0.1", 4243, "tcp://:7777"); addr != "tcp://127.0.0.1:7777" {
+	if addr, err := ParseHost("127.0.0.1", 4243, "tcp://:7777"); err != nil || addr != "tcp://127.0.0.1:7777" {
 		t.Errorf("tcp://:7777 -> expected tcp://127.0.0.1:7777, got %s", addr)
 	}
-	if addr := ParseHost("127.0.0.1", 4243, "unix:///var/run/docker.sock"); addr != "unix:///var/run/docker.sock" {
+	if addr, err := ParseHost("127.0.0.1", 4243, "unix:///var/run/docker.sock"); err != nil || addr != "unix:///var/run/docker.sock" {
 		t.Errorf("unix:///var/run/docker.sock -> expected unix:///var/run/docker.sock, got %s", addr)
 	}
+	if addr, err := ParseHost("127.0.0.1", 4243, "udp://127.0.0.1"); err == nil {
+		t.Errorf("udp protocol address expected error return, but err == nil. Got %s", addr)
+	}
 }
 
 func TestParseRepositoryTag(t *testing.T) {