Set a default request timeout for discovery client

staging/src/k8s.io/client-go/discovery/BUILD

@@ -35,12 +35,10 @@ go_library(
 go_test(
     name = "go_default_xtest",
     srcs = [
-        "discovery_client_test.go",
         "helper_blackbox_test.go",
         "restmapper_test.go",
     ],
     deps = [
-        "//vendor/github.com/gogo/protobuf/proto:go_default_library",
         "//vendor/github.com/googleapis/gnostic/OpenAPIv2:go_default_library",
         "//vendor/github.com/stretchr/testify/assert:go_default_library",
         "//vendor/k8s.io/api/core/v1:go_default_library",
@@ -73,3 +71,18 @@ filegroup(
     ],
     tags = ["automanaged"],
 )
+
+go_test(
+    name = "go_default_test",
+    srcs = ["discovery_client_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "//vendor/github.com/gogo/protobuf/proto:go_default_library",
+        "//vendor/github.com/googleapis/gnostic/OpenAPIv2:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/version:go_default_library",
+        "//vendor/k8s.io/client-go/rest:go_default_library",
+    ],
+)

staging/src/k8s.io/client-go/discovery/discovery_client.go

@@ -22,6 +22,7 @@ import (
 	"net/url"
 	"sort"
 	"strings"
+	"time"
 
 	"github.com/golang/protobuf/proto"
 	"github.com/googleapis/gnostic/OpenAPIv2"
@@ -43,6 +44,13 @@ const (
 	mimePb = "application/com.github.proto-openapi.spec.v2@v1.0+protobuf"
 )
 
+var (
+	// defaultTimeout is the maximum amount of time per request when no timeout has been set on a RESTClient.
+	// Defaults to 32s in order to have a distinguishable length of time, relative to other timeouts that exist.
+	// It's a variable to be able to change it in tests.
+	defaultTimeout = 32 * time.Second
+)
+
 // DiscoveryInterface holds the methods that discover server-supported API groups,
 // versions and resources.
 type DiscoveryInterface interface {
@@ -373,6 +381,9 @@ func withRetries(maxRetries int, f func() ([]*metav1.APIResourceList, error)) ([
 func setDiscoveryDefaults(config *restclient.Config) error {
 	config.APIPath = ""
 	config.GroupVersion = nil
+	if config.Timeout == 0 {
+		config.Timeout = defaultTimeout
+	}
 	codec := runtime.NoopEncoder{Decoder: scheme.Codecs.UniversalDecoder()}
 	config.NegotiatedSerializer = serializer.NegotiatedSerializerWrapper(runtime.SerializerInfo{Serializer: codec})
 	if len(config.UserAgent) == 0 {

staging/src/k8s.io/client-go/discovery/discovery_client_test.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package discovery_test
+package discovery
 
 import (
 	"encoding/json"
@@ -23,7 +23,9 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"reflect"
+	"strings"
 	"testing"
+	"time"
 
 	"github.com/gogo/protobuf/proto"
 	"github.com/googleapis/gnostic/OpenAPIv2"
@@ -32,7 +34,6 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/version"
-	. "k8s.io/client-go/discovery"
 	restclient "k8s.io/client-go/rest"
 )
 
@@ -129,6 +130,21 @@ func TestGetServerGroupsWithBrokenServer(t *testing.T) {
 		}
 	}
 }
+func TestGetServerGroupsWithTimeout(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		time.Sleep(2 * time.Second)
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+	tmp := defaultTimeout
+	defaultTimeout = 1 * time.Second
+	client := NewDiscoveryClientForConfigOrDie(&restclient.Config{Host: server.URL})
+	_, err := client.ServerGroups()
+	if err == nil || strings.Contains(err.Error(), "deadline") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	defaultTimeout = tmp
+}
 
 func TestGetServerResourcesWithV1Server(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {

staging/src/k8s.io/client-go/rest/request.go

@@ -353,8 +353,8 @@ func (r *Request) SetHeader(key string, values ...string) *Request {
 	return r
 }
 
-// Timeout makes the request use the given duration as a timeout. Sets the "timeout"
-// parameter.
+// Timeout makes the request use the given duration as an overall timeout for the
+// request. Additionally, if set passes the value as "timeout" parameter in URL.
 func (r *Request) Timeout(d time.Duration) *Request {
 	if r.err != nil {
 		return r
@@ -640,7 +640,6 @@ func (r *Request) request(fn func(*http.Request, *http.Response)) error {
 	}
 
 	// Right now we make about ten retry attempts if we get a Retry-After response.
-	// TODO: Change to a timeout based approach.
 	maxRetries := 10
 	retries := 0
 	for {
@@ -649,6 +648,14 @@ func (r *Request) request(fn func(*http.Request, *http.Response)) error {
 		if err != nil {
 			return err
 		}
+		if r.timeout > 0 {
+			if r.ctx == nil {
+				r.ctx = context.Background()
+			}
+			var cancelFn context.CancelFunc
+			r.ctx, cancelFn = context.WithTimeout(r.ctx, r.timeout)
+			defer cancelFn()
+		}
 		if r.ctx != nil {
 			req = req.WithContext(r.ctx)
 		}