use istio client-go library instead of knative (#1661)

use istio client-go library instead of knative
bump kubernetes dependency version
change code coverage to codecov

vendor/k8s.io/apimachinery/pkg/util/net/http.go

@@ -68,14 +68,17 @@ func IsProbableEOF(err error) bool {
 	if uerr, ok := err.(*url.Error); ok {
 		err = uerr.Err
 	}
+	msg := err.Error()
 	switch {
 	case err == io.EOF:
 		return true
-	case err.Error() == "http: can't write HTTP request on broken connection":
+	case msg == "http: can't write HTTP request on broken connection":
 		return true
-	case strings.Contains(err.Error(), "connection reset by peer"):
+	case strings.Contains(msg, "http2: server sent GOAWAY and closed the connection"):
 		return true
-	case strings.Contains(strings.ToLower(err.Error()), "use of closed network connection"):
+	case strings.Contains(msg, "connection reset by peer"):
+		return true
+	case strings.Contains(strings.ToLower(msg), "use of closed network connection"):
 		return true
 	}
 	return false
@@ -98,6 +101,9 @@ func SetOldTransportDefaults(t *http.Transport) *http.Transport {
 	if t.TLSHandshakeTimeout == 0 {
 		t.TLSHandshakeTimeout = defaultTransport.TLSHandshakeTimeout
 	}
+	if t.IdleConnTimeout == 0 {
+		t.IdleConnTimeout = defaultTransport.IdleConnTimeout
+	}
 	return t
 }
 
@@ -108,7 +114,7 @@ func SetTransportDefaults(t *http.Transport) *http.Transport {
 	// Allow clients to disable http2 if needed.
 	if s := os.Getenv("DISABLE_HTTP2"); len(s) > 0 {
 		klog.Infof("HTTP2 has been explicitly disabled")
-	} else {
+	} else if allowsHTTP2(t) {
 		if err := http2.ConfigureTransport(t); err != nil {
 			klog.Warningf("Transport failed http2 configuration: %v", err)
 		}
@@ -116,6 +122,21 @@ func SetTransportDefaults(t *http.Transport) *http.Transport {
 	return t
 }
 
+func allowsHTTP2(t *http.Transport) bool {
+	if t.TLSClientConfig == nil || len(t.TLSClientConfig.NextProtos) == 0 {
+		// the transport expressed no NextProto preference, allow
+		return true
+	}
+	for _, p := range t.TLSClientConfig.NextProtos {
+		if p == http2.NextProtoTLS {
+			// the transport explicitly allowed http/2
+			return true
+		}
+	}
+	// the transport explicitly set NextProtos and excluded http/2
+	return false
+}
+
 type RoundTripperWrapper interface {
 	http.RoundTripper
 	WrappedRoundTripper() http.RoundTripper

vendor/k8s.io/apimachinery/pkg/util/net/util.go

@@ -54,3 +54,20 @@ func IsConnectionReset(err error) bool {
 	}
 	return false
 }
+
+// Returns if the given err is "connection refused" error
+func IsConnectionRefused(err error) bool {
+	if urlErr, ok := err.(*url.Error); ok {
+		err = urlErr.Err
+	}
+	if opErr, ok := err.(*net.OpError); ok {
+		err = opErr.Err
+	}
+	if osErr, ok := err.(*os.SyscallError); ok {
+		err = osErr.Err
+	}
+	if errno, ok := err.(syscall.Errno); ok && errno == syscall.ECONNREFUSED {
+		return true
+	}
+	return false
+}