Golang sysctl.GetSysctl函数代码示例

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)
	return err
}

// setupKernelTunables validates kernel tunable flags are set as expected
// depending upon the specified option, it will either warn, error, or modify the kernel tunable flags
func setupKernelTunables(option KernelTunableBehavior) error {
	desiredState := map[string]int{
		utilsysctl.VmOvercommitMemory: utilsysctl.VmOvercommitMemoryAlways,
		utilsysctl.VmPanicOnOOM:       utilsysctl.VmPanicOnOOMInvokeOOMKiller,
		utilsysctl.KernelPanic:        utilsysctl.KernelPanicRebootTimeout,
		utilsysctl.KernelPanicOnOops:  utilsysctl.KernelPanicOnOopsAlways,
	}

	errList := []error{}
	for flag, expectedValue := range desiredState {
		val, err := utilsysctl.GetSysctl(flag)
		if err != nil {
			errList = append(errList, err)
			continue
		}
		if val == expectedValue {
			continue
		}

		switch option {
		case KernelTunableError:
			errList = append(errList, fmt.Errorf("Invalid kernel flag: %v, expected value: %v, actual value: %v", flag, expectedValue, val))
		case KernelTunableWarn:
			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)
			if err != nil {
				errList = append(errList, err)
			}
		}
	}
	return utilerrors.NewAggregate(errList)
}

// ShouldUseIptablesProxier returns true if we should use the iptables Proxier
// instead of the "classic" userspace Proxier.  This is determined by checking
// the iptables version and for the existence of kernel features. It may return
// an error if it fails to get the iptables version without error, in which
// case it will also return false.
func ShouldUseIptablesProxier() (bool, error) {
	exec := utilexec.New()
	minVersion, err := semver.NewVersion(iptablesMinVersion)
	if err != nil {
		return false, err
	}
	// returns "X.X.X", err
	versionString, err := utiliptables.GetIptablesVersionString(exec)
	if err != nil {
		return false, err
	}
	version, err := semver.NewVersion(versionString)
	if err != nil {
		return false, err
	}
	if version.LessThan(*minVersion) {
		return false, nil
	}

	// Check for the required sysctls.  We don't care about the value, just
	// that it exists.  If this Proxier is chosen, we'll iniialize it as we
	// need.
	_, err = utilsysctl.GetSysctl(sysctlRouteLocalnet)
	if err != nil {
		return false, err
	}

	return true, nil
}

// CanUseIptablesProxier returns true if we should use the iptables Proxier
// instead of the "classic" userspace Proxier.  This is determined by checking
// the iptables version and for the existence of kernel features. It may return
// an error if it fails to get the iptables version without error, in which
// case it will also return false.
func CanUseIptablesProxier(iptver IptablesVersioner) (bool, error) {
	minVersion, err := semver.NewVersion(iptablesMinVersion)
	if err != nil {
		return false, err
	}
	// returns "X.Y.Z"
	versionString, err := iptver.GetVersion()
	if err != nil {
		return false, err
	}
	version, err := semver.NewVersion(versionString)
	if err != nil {
		return false, err
	}
	if version.LessThan(*minVersion) {
		return false, nil
	}

	// Check for the required sysctls.  We don't care about the value, just
	// that it exists.  If this Proxier is chosen, we'll iniialize it as we
	// need.
	// TODO: we should inject a sysctl.Interface like we do for iptables
	_, err = utilsysctl.GetSysctl(sysctlRouteLocalnet)
	if err != nil {
		return false, err
	}

	return true, nil
}

// NewProxier returns a new Proxier given an iptables Interface instance.
// Because of the iptables logic, it is assumed that there is only a single Proxier active on a machine.
// 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) (*Proxier, error) {
	// Set the route_localnet sysctl we need for
	if err := utilsysctl.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 {
		glog.Infof("missing br-netfilter module or unset sysctl br-nf-call-iptables; proxy may not work as intended")
	}

	// Generate the masquerade mark to use for SNAT rules.
	if masqueradeBit < 0 || masqueradeBit > 31 {
		return nil, fmt.Errorf("invalid iptables-masquerade-bit %v not in [0, 31]", masqueradeBit)
	}
	masqueradeValue := 1 << uint(masqueradeBit)
	masqueradeMark := fmt.Sprintf("%#08x/%#08x", masqueradeValue, masqueradeValue)

	return &Proxier{
		serviceMap:     make(map[proxy.ServicePortName]*serviceInfo),
		endpointsMap:   make(map[proxy.ServicePortName][]string),
		portsMap:       make(map[localPort]closeable),
		syncPeriod:     syncPeriod,
		iptables:       ipt,
		masqueradeAll:  masqueradeAll,
		masqueradeMark: masqueradeMark,
		exec:           exec,
		clusterCIDR:    clusterCIDR,
	}, nil
}

// sysctlSomaxconn returns the value of net.core.somaxconn, i.e.
// maximum number of connections that can be queued for acceptance
// http://nginx.org/en/docs/http/ngx_http_core_module.html#listen
func sysctlSomaxconn() int {
	maxConns, err := sysctl.GetSysctl("net.core.somaxconn")
	if err != nil || maxConns < 512 {
		glog.Warningf("system net.core.somaxconn=%v. Using NGINX default (511)", maxConns)
		return 511
	}

	return maxConns
}

// disableKernelMemoryOvercommitHandling tells the kernel to perform no memory over-commit handling.
// Under this setting, the potential for memory overload is increased, but so is performance for
// memory-intensive tasks
// sets /proc/sys/vm/overcommit_memory to 1
func disableKernelMemoryOvercommitHandling() error {
	val, err := utilsysctl.GetSysctl(sysctlVmOvercommitMemory)
	if err != nil {
		return err
	}
	if val == 1 {
		return nil
	}
	glog.V(2).Infof("Updating kernel memory overcommit flag from %v to %v", val, 1)
	err = utilsysctl.SetSysctl(sysctlVmOvercommitMemory, 1)
	if err != nil {
		return err
	}
	return nil
}