Create testable implementation of sysctl

This is so we can test kubenet Init, which calls sysctl

cmd/kube-proxy/app/conntrack.go

@@ -38,7 +38,7 @@ var readOnlySysFSError = errors.New("ReadOnlySysFS")
 
 func (realConntracker) SetMax(max int) error {
 	glog.Infof("Setting nf_conntrack_max to %d", max)
-	if err := sysctl.SetSysctl("net/netfilter/nf_conntrack_max", max); err != nil {
+	if err := sysctl.New().SetSysctl("net/netfilter/nf_conntrack_max", max); err != nil {
 		return err
 	}
 	// sysfs is expected to be mounted as 'rw'. However, it may be unexpectedly mounted as
@@ -60,7 +60,7 @@ func (realConntracker) SetMax(max int) error {
 
 func (realConntracker) SetTCPEstablishedTimeout(seconds int) error {
 	glog.Infof("Setting nf_conntrack_tcp_timeout_established to %d", seconds)
-	return sysctl.SetSysctl("net/netfilter/nf_conntrack_tcp_timeout_established", seconds)
+	return sysctl.New().SetSysctl("net/netfilter/nf_conntrack_tcp_timeout_established", seconds)
 }
 
 // isSysFSWritable checks /proc/mounts to see whether sysfs is 'rw' or not.

cmd/kube-proxy/app/server.go

@@ -47,6 +47,7 @@ import (
 	nodeutil "k8s.io/kubernetes/pkg/util/node"
 	"k8s.io/kubernetes/pkg/util/oom"
 	"k8s.io/kubernetes/pkg/util/resourcecontainer"
+	utilsysctl "k8s.io/kubernetes/pkg/util/sysctl"
 	"k8s.io/kubernetes/pkg/util/wait"
 
 	"github.com/golang/glog"
@@ -204,7 +205,7 @@ func NewProxyServerDefault(config *options.ProxyServerConfig) (*ProxyServer, err
 			// IPTablesMasqueradeBit must be specified or defaulted.
 			return nil, fmt.Errorf("Unable to read IPTablesMasqueradeBit from config")
 		}
-		proxierIptables, err := iptables.NewProxier(iptInterface, execer, config.IPTablesSyncPeriod.Duration, config.MasqueradeAll, int(*config.IPTablesMasqueradeBit), config.ClusterCIDR, hostname, getNodeIP(client, hostname))
+		proxierIptables, err := iptables.NewProxier(iptInterface, utilsysctl.New(), execer, config.IPTablesSyncPeriod.Duration, config.MasqueradeAll, int(*config.IPTablesMasqueradeBit), config.ClusterCIDR, hostname, getNodeIP(client, hostname))
 		if err != nil {
 			glog.Fatalf("Unable to create proxier: %v", err)
 		}

pkg/kubelet/cm/container_manager_linux.go

@@ -270,9 +270,11 @@ func setupKernelTunables(option KernelTunableBehavior) error {
 		utilsysctl.KernelPanicOnOops:  utilsysctl.KernelPanicOnOopsAlways,
 	}
 
+	sysctl := utilsysctl.New()
+
 	errList := []error{}
 	for flag, expectedValue := range desiredState {
-		val, err := utilsysctl.GetSysctl(flag)
+		val, err := sysctl.GetSysctl(flag)
 		if err != nil {
 			errList = append(errList, err)
 			continue
@@ -288,7 +290,7 @@ func setupKernelTunables(option KernelTunableBehavior) error {
 			glog.V(2).Infof("Invalid kernel flag: %v, expected value: %v, actual value: %v", flag, expectedValue, val)
 		case KernelTunableModify:
 			glog.V(2).Infof("Updating kernel flag: %v, expected value: %v, actual value: %v", flag, expectedValue, val)
-			err = utilsysctl.SetSysctl(flag, expectedValue)
+			err = sysctl.SetSysctl(flag, expectedValue)
 			if err != nil {
 				errList = append(errList, err)
 			}

pkg/kubelet/network/kubenet/kubenet_linux.go

@@ -71,6 +71,7 @@ type kubenetNetworkPlugin struct {
 	hairpinMode     componentconfig.HairpinMode
 	hostportHandler hostport.HostportHandler
 	iptables        utiliptables.Interface
+	sysctl          utilsysctl.Interface
 	// vendorDir is passed by kubelet network-plugin-dir parameter.
 	// kubenet will search for cni binaries in DefaultCNIDir first, then continue to vendorDir.
 	vendorDir         string
@@ -115,7 +116,7 @@ func (plugin *kubenetNetworkPlugin) Init(host network.Host, hairpinMode componen
 	// was built-in, we simply ignore the error here. A better thing to do is
 	// to check the kernel version in the future.
 	plugin.execer.Command("modprobe", "br-netfilter").CombinedOutput()
-	err := utilsysctl.SetSysctl(sysctlBridgeCallIptables, 1)
+	err := plugin.sysctl.SetSysctl(sysctlBridgeCallIptables, 1)
 	if err != nil {
 		glog.Warningf("can't set sysctl %s: %v", sysctlBridgeCallIptables, err)
 	}

pkg/kubelet/network/plugins.go

@@ -166,7 +166,7 @@ func (plugin *NoopNetworkPlugin) Init(host Host, hairpinMode componentconfig.Hai
 	// Ensure the netfilter module is loaded on kernel >= 3.18; previously
 	// it was built-in.
 	utilexec.New().Command("modprobe", "br-netfilter").CombinedOutput()
-	if err := utilsysctl.SetSysctl(sysctlBridgeCallIptables, 1); err != nil {
+	if err := utilsysctl.New().SetSysctl(sysctlBridgeCallIptables, 1); err != nil {
 		glog.Warningf("can't set sysctl %s: %v", sysctlBridgeCallIptables, err)
 	}
 

pkg/proxy/iptables/proxier.go

@@ -123,7 +123,7 @@ func (lkct LinuxKernelCompatTester) IsCompatible() error {
 	// Check for the required sysctls.  We don't care about the value, just
 	// that it exists.  If this Proxier is chosen, we'll initialize it as we
 	// need.
-	_, err := utilsysctl.GetSysctl(sysctlRouteLocalnet)
+	_, err := utilsysctl.New().GetSysctl(sysctlRouteLocalnet)
 	return err
 }
 
@@ -195,16 +195,16 @@ var _ proxy.ProxyProvider = &Proxier{}
 // An error will be returned if iptables fails to update or acquire the initial lock.
 // Once a proxier is created, it will keep iptables up to date in the background and
 // will not terminate if a particular iptables call fails.
-func NewProxier(ipt utiliptables.Interface, exec utilexec.Interface, syncPeriod time.Duration, masqueradeAll bool, masqueradeBit int, clusterCIDR string, hostname string, nodeIP net.IP) (*Proxier, error) {
+func NewProxier(ipt utiliptables.Interface, sysctl utilsysctl.Interface, exec utilexec.Interface, syncPeriod time.Duration, masqueradeAll bool, masqueradeBit int, clusterCIDR string, hostname string, nodeIP net.IP) (*Proxier, error) {
 	// Set the route_localnet sysctl we need for
-	if err := utilsysctl.SetSysctl(sysctlRouteLocalnet, 1); err != nil {
+	if err := sysctl.SetSysctl(sysctlRouteLocalnet, 1); err != nil {
 		return nil, fmt.Errorf("can't set sysctl %s: %v", sysctlRouteLocalnet, err)
 	}
 
 	// Proxy needs br_netfilter and bridge-nf-call-iptables=1 when containers
 	// are connected to a Linux bridge (but not SDN bridges).  Until most
 	// plugins handle this, log when config is missing
-	if val, err := utilsysctl.GetSysctl(sysctlBridgeCallIptables); err == nil && val != 1 {
+	if val, err := sysctl.GetSysctl(sysctlBridgeCallIptables); err == nil && val != 1 {
 		glog.Infof("missing br-netfilter module or unset sysctl br-nf-call-iptables; proxy may not work as intended")
 	}
 

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{})