Fix ipv6/ipv4 name resolution

config/global_ips.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"context"
 	"io/ioutil"
 	"net"
 	"net/http"
@@ -9,16 +10,28 @@ import (
 	"github.com/juju/errors"
 )
 
+const ifconfigAddress = "https://ifconfig.co/ip"
+
 func getGlobalIPv4() (net.IP, error) {
-	return fetchIP("https://v4.ifconfig.co/ip")
+	return fetchIP("tcp4")
 }
 
 func getGlobalIPv6() (net.IP, error) {
-	return fetchIP("https://v6.ifconfig.co/ip")
+	return fetchIP("tcp6")
 }
 
-func fetchIP(url string) (net.IP, error) {
-	resp, err := http.Get(url)
+func fetchIP(network string) (net.IP, error) {
+	dialer := &net.Dialer{DualStack: false}
+	client := &http.Client{
+		Jar: nil,
+		Transport: &http.Transport{
+			DialContext: func(ctx context.Context, _, addr string) (net.Conn, error) {
+				return dialer.DialContext(ctx, network, addr)
+			},
+		},
+	}
+
+	resp, err := client.Get(ifconfigAddress)
 	if err != nil {
 		return nil, err
 	}