Merge pull request kubernetes#81776 from sttts/sttts-hide-suppressing-panic-for-copyResponse

apimachinery: hide 'suppressing panic for copyResponse' error' in ReverseProxy

Author: k8s-ci-robot

staging/src/k8s.io/apimachinery/pkg/util/proxy/upgradeaware.go

@@ -23,10 +23,12 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"log"
 	"net"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
+	"os"
 	"strings"
 	"time"
 
@@ -230,9 +232,22 @@ func (h *UpgradeAwareHandler) ServeHTTP(w http.ResponseWriter, req *http.Request
 	proxy := httputil.NewSingleHostReverseProxy(&url.URL{Scheme: h.Location.Scheme, Host: h.Location.Host})
 	proxy.Transport = h.Transport
 	proxy.FlushInterval = h.FlushInterval
+	proxy.ErrorLog = log.New(noSuppressPanicError{}, "", log.LstdFlags)
 	proxy.ServeHTTP(w, newReq)
 }
 
+type noSuppressPanicError struct{}
+
+func (noSuppressPanicError) Write(p []byte) (n int, err error) {
+	// skip "suppressing panic for copyResponse error in test; copy error" error message
+	// that ends up in CI tests on each kube-apiserver termination as noise and
+	// everybody thinks this is fatal.
+	if strings.Contains(string(p), "suppressing panic") {
+		return len(p), nil
+	}
+	return os.Stderr.Write(p)
+}
+
 // tryUpgrade returns true if the request was handled.
 func (h *UpgradeAwareHandler) tryUpgrade(w http.ResponseWriter, req *http.Request) bool {
 	if !httpstream.IsUpgradeRequest(req) {