From ad330f7dbe85a6ebc4629e1ff2da2f62b20a254a Mon Sep 17 00:00:00 2001
From: Krzysztof Jastrzebski <kjastrzebski@google.com>
Date: Mon, 17 Sep 2018 20:42:18 +0200
Subject: [PATCH] Start synchronizing pods after network is ready.

---
 pkg/kubelet/BUILD          |  1 +
 pkg/kubelet/errors.go      | 21 +++++++++++++++++++++
 pkg/kubelet/kubelet.go     |  4 ++--
 pkg/kubelet/pod_workers.go |  9 ++++++++-
 4 files changed, 32 insertions(+), 3 deletions(-)
 create mode 100644 pkg/kubelet/errors.go

diff --git a/pkg/kubelet/BUILD b/pkg/kubelet/BUILD
index 62e4602f929..4bb15d0ecc5 100644
--- a/pkg/kubelet/BUILD
+++ b/pkg/kubelet/BUILD
@@ -11,6 +11,7 @@ go_library(
     srcs = [
         "active_deadline.go",
         "doc.go",
+        "errors.go",
         "kubelet.go",
         "kubelet_getters.go",
         "kubelet_network.go",
diff --git a/pkg/kubelet/errors.go b/pkg/kubelet/errors.go
new file mode 100644
index 00000000000..eae36e5ee59
--- /dev/null
+++ b/pkg/kubelet/errors.go
@@ -0,0 +1,21 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kubelet
+
+const (
+	NetworkNotReadyErrorMsg = "network is not ready"
+)
diff --git a/pkg/kubelet/kubelet.go b/pkg/kubelet/kubelet.go
index 2888c1736a8..27c0a835aa1 100644
--- a/pkg/kubelet/kubelet.go
+++ b/pkg/kubelet/kubelet.go
@@ -1561,8 +1561,8 @@ func (kl *Kubelet) syncPod(o syncPodOptions) error {
 
 	// If the network plugin is not ready, only start the pod if it uses the host network
 	if rs := kl.runtimeState.networkErrors(); len(rs) != 0 && !kubecontainer.IsHostNetworkPod(pod) {
-		kl.recorder.Eventf(pod, v1.EventTypeWarning, events.NetworkNotReady, "network is not ready: %v", rs)
-		return fmt.Errorf("network is not ready: %v", rs)
+		kl.recorder.Eventf(pod, v1.EventTypeWarning, events.NetworkNotReady, "%s: %v", NetworkNotReadyErrorMsg, rs)
+		return fmt.Errorf("%s: %v", NetworkNotReadyErrorMsg, rs)
 	}
 
 	// Create Cgroups for the pod and apply resource parameters
diff --git a/pkg/kubelet/pod_workers.go b/pkg/kubelet/pod_workers.go
index 5a1fb992725..a42589a99c5 100644
--- a/pkg/kubelet/pod_workers.go
+++ b/pkg/kubelet/pod_workers.go
@@ -18,6 +18,7 @@ package kubelet
 
 import (
 	"fmt"
+	"strings"
 	"sync"
 	"time"
 
@@ -96,8 +97,11 @@ const (
 	// jitter factor for resyncInterval
 	workerResyncIntervalJitterFactor = 0.5
 
-	// jitter factor for backOffPeriod
+	// jitter factor for backOffPeriod and backOffOnTransientErrorPeriod
 	workerBackOffPeriodJitterFactor = 0.5
+
+	// backoff period when transient error occurred.
+	backOffOnTransientErrorPeriod = time.Second
 )
 
 type podWorkers struct {
@@ -263,6 +267,9 @@ func (p *podWorkers) wrapUp(uid types.UID, syncErr error) {
 	case syncErr == nil:
 		// No error; requeue at the regular resync interval.
 		p.workQueue.Enqueue(uid, wait.Jitter(p.resyncInterval, workerResyncIntervalJitterFactor))
+	case strings.Contains(syncErr.Error(), NetworkNotReadyErrorMsg):
+		// Network is not ready; back off for short period of time and retry as network might be ready soon.
+		p.workQueue.Enqueue(uid, wait.Jitter(backOffOnTransientErrorPeriod, workerBackOffPeriodJitterFactor))
 	default:
 		// Error occurred during the sync; back off and then retry.
 		p.workQueue.Enqueue(uid, wait.Jitter(p.backOffPeriod, workerBackOffPeriodJitterFactor))