From 71ef46fa122d1fc3bba587640451b697e59f1903 Mon Sep 17 00:00:00 2001
From: Jordan Liggitt <liggitt@google.com>
Date: Mon, 19 Aug 2019 11:23:05 -0400
Subject: [PATCH] Use lesser of context or webhook-specific timeout in webhooks

Kubernetes-commit: c63284b1f3996e7830c1aca85281d349d0091c82
---
 .../plugin/webhook/mutating/dispatcher.go     | 33 +++++++++++++++++--
 .../plugin/webhook/validating/dispatcher.go   | 31 +++++++++++++++--
 2 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/pkg/admission/plugin/webhook/mutating/dispatcher.go b/pkg/admission/plugin/webhook/mutating/dispatcher.go
index cf0e76a60..8c75fdcf2 100644
--- a/pkg/admission/plugin/webhook/mutating/dispatcher.go
+++ b/pkg/admission/plugin/webhook/mutating/dispatcher.go
@@ -136,7 +136,15 @@ func (a *mutatingDispatcher) Dispatch(ctx context.Context, attr admission.Attrib
 			if ignoreClientCallFailures {
 				klog.Warningf("Failed calling webhook, failing open %v: %v", hook.Name, callErr)
 				utilruntime.HandleError(callErr)
-				continue
+
+				select {
+				case <-ctx.Done():
+					// parent context is canceled or timed out, no point in continuing
+					return apierrors.NewTimeoutError("request did not complete within requested timeout", 0)
+				default:
+					// individual webhook timed out, but parent context did not, continue
+					continue
+				}
 			}
 			klog.Warningf("Failed calling webhook, failing closed %v: %v", hook.Name, err)
 			return apierrors.NewInternalError(err)
@@ -181,10 +189,29 @@ func (a *mutatingDispatcher) callAttrMutatingHook(ctx context.Context, h *v1beta
 		utiltrace.Field{"operation", attr.GetOperation()},
 		utiltrace.Field{"UID", uid})
 	defer trace.LogIfLong(500 * time.Millisecond)
-	r := client.Post().Context(ctx).Body(request)
+
+	// if the webhook has a specific timeout, wrap the context to apply it
 	if h.TimeoutSeconds != nil {
-		r = r.Timeout(time.Duration(*h.TimeoutSeconds) * time.Second)
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, time.Duration(*h.TimeoutSeconds)*time.Second)
+		defer cancel()
 	}
+
+	r := client.Post().Context(ctx).Body(request)
+
+	// if the context has a deadline, set it as a parameter to inform the backend
+	if deadline, hasDeadline := ctx.Deadline(); hasDeadline {
+		// compute the timeout
+		if timeout := time.Until(deadline); timeout > 0 {
+			// if it's not an even number of seconds, round up to the nearest second
+			if truncated := timeout.Truncate(time.Second); truncated != timeout {
+				timeout = truncated + time.Second
+			}
+			// set the timeout
+			r.Timeout(timeout)
+		}
+	}
+
 	if err := r.Do().Into(response); err != nil {
 		return false, &webhookutil.ErrCallingWebhook{WebhookName: h.Name, Reason: err}
 	}
diff --git a/pkg/admission/plugin/webhook/validating/dispatcher.go b/pkg/admission/plugin/webhook/validating/dispatcher.go
index 6525524f5..3e1cb589a 100644
--- a/pkg/admission/plugin/webhook/validating/dispatcher.go
+++ b/pkg/admission/plugin/webhook/validating/dispatcher.go
@@ -80,6 +80,14 @@ func (d *validatingDispatcher) Dispatch(ctx context.Context, attr admission.Attr
 		return nil
 	}
 
+	// Check if the request has already timed out before spawning remote calls
+	select {
+	case <-ctx.Done():
+		// parent context is canceled or timed out, no point in continuing
+		return apierrors.NewTimeoutError("request did not complete within requested timeout", 0)
+	default:
+	}
+
 	wg := sync.WaitGroup{}
 	errCh := make(chan error, len(relevantHooks))
 	wg.Add(len(relevantHooks))
@@ -162,10 +170,29 @@ func (d *validatingDispatcher) callHook(ctx context.Context, h *v1beta1.Validati
 		utiltrace.Field{"operation", attr.GetOperation()},
 		utiltrace.Field{"UID", uid})
 	defer trace.LogIfLong(500 * time.Millisecond)
-	r := client.Post().Context(ctx).Body(request)
+
+	// if the webhook has a specific timeout, wrap the context to apply it
 	if h.TimeoutSeconds != nil {
-		r = r.Timeout(time.Duration(*h.TimeoutSeconds) * time.Second)
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, time.Duration(*h.TimeoutSeconds)*time.Second)
+		defer cancel()
 	}
+
+	r := client.Post().Context(ctx).Body(request)
+
+	// if the context has a deadline, set it as a parameter to inform the backend
+	if deadline, hasDeadline := ctx.Deadline(); hasDeadline {
+		// compute the timeout
+		if timeout := time.Until(deadline); timeout > 0 {
+			// if it's not an even number of seconds, round up to the nearest second
+			if truncated := timeout.Truncate(time.Second); truncated != timeout {
+				timeout = truncated + time.Second
+			}
+			// set the timeout
+			r.Timeout(timeout)
+		}
+	}
+
 	if err := r.Do().Into(response); err != nil {
 		return &webhookutil.ErrCallingWebhook{WebhookName: h.Name, Reason: err}
 	}