Merge pull request #38592 from krousey/client-context

Automatic merge from submit-queue (batch tested with PRs 38592, 39949, 39946, 39882)

Add optional per-request context to restclient

**What this PR does / why we need it**: It adds per-request contexts to restclient's API, and uses them to add timeouts to all proxy calls in the e2e tests. An entire e2e shouldn't hang for hours on a single API call.

**Which issue this PR fixes**: #38305

**Special notes for your reviewer**:

This adds a feature to the low-level rest client request feature that is entirely optional. It doesn't affect any requests that don't use it. The api of the generated clients does not change, and they currently don't take advantage of this.

I intend to patch this in to 1.5 as a mostly test only change since it's not going to affect any controller, generated client, or user of the generated client.


cc @kubernetes/sig-api-machinery 
cc @saad-ali

test/e2e/examples.go

@@ -17,6 +17,7 @@ limitations under the License.
 package e2e
 
 import (
+	"context"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -580,7 +581,12 @@ func makeHttpRequestToService(c clientset.Interface, ns, service, path string, t
 		if errProxy != nil {
 			break
 		}
+
+		ctx, cancel := context.WithTimeout(context.Background(), framework.SingleCallTimeout)
+		defer cancel()
+
 		result, err = proxyRequest.Namespace(ns).
+			Context(ctx).
 			Name(service).
 			Suffix(path).
 			Do().