Set a default request timeout for discovery client

Kubernetes-commit: 7bd48a7e2325381cb777d0ea1ff89b2ecece23b6

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 {