Use ipv6 dialer, the rest are defaults

pkg/http/client.go

@@ -29,7 +29,7 @@ type HTTPClient struct {
 }
 
 func NewHTTPClient(token string, maxRetries int, timeoutSecs int, cfg config.ConfigInterface, log *zap.SugaredLogger) *HTTPClient {
-	return &HTTPClient{
+	client := HTTPClient{
 		bearerToken: token,
 		client: &http.Client{
 			Timeout: time.Duration(timeoutSecs) * time.Second,
@@ -63,6 +63,32 @@ func NewHTTPClient(token string, maxRetries int, timeoutSecs int, cfg config.Con
 		ipv6: cmap.New[net.IP](),
 		log:  log,
 	}
+
+	if cfg.ShouldForceIPv6() {
+		dialer := &net.Dialer{}
+
+		dialContext := func(ctx context.Context, network, address string) (net.Conn, error) {
+			ips, err := net.DefaultResolver.LookupIPAddr(ctx, address)
+			if err != nil {
+				return nil, err
+			}
+
+			for _, ip := range ips {
+				if ip.IP.To4() == nil { // IPv6 address found
+					ipv6Address := "[" + ip.IP.String() + "]"
+					return dialer.DialContext(ctx, network, ipv6Address)
+				}
+			}
+			return nil, net.UnknownNetworkError("no IPv6 address found")
+		}
+
+		transport := &http.Transport{
+			DialContext: dialContext,
+		}
+		client.client.Transport = transport
+	}
+
+	return &client
 }
 
 func (r *HTTPClient) Do(req *http.Request) (*http.Response, error) {
@@ -77,40 +103,6 @@ func (r *HTTPClient) Do(req *http.Request) (*http.Response, error) {
 		req.Header.Set("Authorization", "Bearer "+r.bearerToken)
 	}
 
-	if r.cfg.ShouldForceIPv6() {
-		dialer := &net.Dialer{}
-		transport := r.client.Transport.(*http.Transport).Clone()
-		transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
-			host, port, err := net.SplitHostPort(addr)
-			if err != nil {
-				return nil, err
-			}
-			if ipv6, ok := r.ipv6.Get(host); !ok {
-				// Lookup IP address if not found in map
-				ips, err := net.LookupIP(host)
-				if err != nil {
-					return nil, err
-				}
-				for _, ip := range ips {
-					if ip.To4() == nil { // IPv6
-						ipv6 = ip
-						r.ipv6.Set(host, ipv6)
-						break
-					}
-				}
-				if ipv6 == nil { // No IPv6 address found, fallback to default
-					addr = net.JoinHostPort(host, port)
-				} else {
-					addr = net.JoinHostPort(ipv6.String(), port)
-				}
-			} else if ipv6 != nil && host == req.URL.Hostname() {
-				addr = net.JoinHostPort(ipv6.String(), port)
-			}
-			return dialer.DialContext(ctx, network, addr)
-		}
-		r.client.Transport = transport
-	}
-
 	var resp *http.Response
 	var err error
 	attempt := 0