Merge pull request #30376 from justinsb/kubenet_mtu

Automatic merge from submit-queue

Add kubelet --network-plugin-mtu flag for MTU selection

* Add network-plugin-mtu option which lets us pass down a MTU to a network provider (currently processed by kubenet)
* Add a test, and thus make sysctl testable

pkg/util/sysctl/sysctl.go

@@ -37,8 +37,25 @@ const (
 	KernelPanicRebootTimeout = 10 // seconds after a panic for the kernel to reboot
 )
 
+// An injectable interface for running sysctl commands.
+type Interface interface {
+	// GetSysctl returns the value for the specified sysctl setting
+	GetSysctl(sysctl string) (int, error)
+	// SetSysctl modifies the specified sysctl flag to the new value
+	SetSysctl(sysctl string, newVal int) error
+}
+
+// New returns a new Interface for accessing sysctl
+func New() Interface {
+	return &procSysctl{}
+}
+
+// procSysctl implements Interface by reading and writing files under /proc/sys
+type procSysctl struct {
+}
+
 // GetSysctl returns the value for the specified sysctl setting
-func GetSysctl(sysctl string) (int, error) {
+func (_ *procSysctl) GetSysctl(sysctl string) (int, error) {
 	data, err := ioutil.ReadFile(path.Join(sysctlBase, sysctl))
 	if err != nil {
 		return -1, err
@@ -51,6 +68,6 @@ func GetSysctl(sysctl string) (int, error) {
 }
 
 // SetSysctl modifies the specified sysctl flag to the new value
-func SetSysctl(sysctl string, newVal int) error {
+func (_ *procSysctl) SetSysctl(sysctl string, newVal int) error {
 	return ioutil.WriteFile(path.Join(sysctlBase, sysctl), []byte(strconv.Itoa(newVal)), 0640)
 }

pkg/util/sysctl/testing/fake.go

@@ -0,0 +1,50 @@
+/*
+Copyright 2015 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 testing
+
+import (
+	"k8s.io/kubernetes/pkg/util/sysctl"
+	"os"
+)
+
+// fake is a map-backed implementation of sysctl.Interface, for testing/mocking
+type fake struct {
+	Settings map[string]int
+}
+
+func NewFake() *fake {
+	return &fake{
+		Settings: make(map[string]int),
+	}
+}
+
+// GetSysctl returns the value for the specified sysctl setting
+func (m *fake) GetSysctl(sysctl string) (int, error) {
+	v, found := m.Settings[sysctl]
+	if !found {
+		return -1, os.ErrNotExist
+	}
+	return v, nil
+}
+
+// SetSysctl modifies the specified sysctl flag to the new value
+func (m *fake) SetSysctl(sysctl string, newVal int) error {
+	m.Settings[sysctl] = newVal
+	return nil
+}
+
+var _ = sysctl.Interface(&fake{})