Lightweight Kubernetes
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//go:build !windows
package syssetup
import (
"os"
"os/exec"
"runtime"
"time"
"github.com/google/cadvisor/machine"
"github.com/google/cadvisor/utils/sysfs"
"github.com/sirupsen/logrus"
"k8s.io/component-helpers/node/util/sysctl"
kubeproxyconfig "k8s.io/kubernetes/pkg/proxy/apis/config"
)
func loadKernelModule(moduleName string) {
if _, err := os.Stat("/sys/module/" + moduleName); err == nil {
logrus.Info("Module " + moduleName + " was already loaded")
return
}
if err := exec.Command("modprobe", "--", moduleName).Run(); err != nil {
logrus.Warnf("Failed to load kernel module %v with modprobe", moduleName)
}
}
// Configure loads required kernel modules and sets sysctls required for other components to
// function properly.
func Configure(enableIPv6 bool, config *kubeproxyconfig.KubeProxyConntrackConfiguration) {
loadKernelModule("overlay")
loadKernelModule("nf_conntrack")
loadKernelModule("br_netfilter")
loadKernelModule("iptable_nat")
loadKernelModule("iptable_filter")
if enableIPv6 {
loadKernelModule("ip6table_nat")
loadKernelModule("ip6table_filter")
}
// Kernel is inconsistent about how devconf is configured for
// new network namespaces between ipv4 and ipv6. Make sure to
// enable forwarding on all and default for both ipv4 and ipv6.
sysctls := map[string]int{
"net/ipv4/conf/all/forwarding": 1,
"net/ipv4/conf/default/forwarding": 1,
"net/bridge/bridge-nf-call-iptables": 1,
}
if enableIPv6 {
sysctls["net/ipv6/conf/all/forwarding"] = 1
sysctls["net/ipv6/conf/default/forwarding"] = 1
sysctls["net/bridge/bridge-nf-call-ip6tables"] = 1
sysctls["net/core/devconf_inherit_init_net"] = 1
}
if conntrackMax := getConntrackMax(config); conntrackMax > 0 {
sysctls["net/netfilter/nf_conntrack_max"] = conntrackMax
}
if config.TCPEstablishedTimeout.Duration > 0 {
sysctls["net/netfilter/nf_conntrack_tcp_timeout_established"] = int(config.TCPEstablishedTimeout.Duration / time.Second)
}
if config.TCPCloseWaitTimeout.Duration > 0 {
sysctls["net/netfilter/nf_conntrack_tcp_timeout_close_wait"] = int(config.TCPCloseWaitTimeout.Duration / time.Second)
}
sys := sysctl.New()
for entry, value := range sysctls {
if val, _ := sys.GetSysctl(entry); val != value {
logrus.Infof("Set sysctl '%v' to %v", entry, value)
if err := sys.SetSysctl(entry, value); err != nil {
logrus.Errorf("Failed to set sysctl: %v", err)
}
}
}
}
// getConntrackMax is cribbed from kube-proxy, as recent kernels no longer allow non-init namespaces
// to set conntrack-related sysctls.
// ref: https://github.com/kubernetes/kubernetes/blob/v1.21.1/cmd/kube-proxy/app/server.go#L780
// ref: https://github.com/kubernetes-sigs/kind/issues/2240
func getConntrackMax(config *kubeproxyconfig.KubeProxyConntrackConfiguration) int {
if config.MaxPerCore != nil && *config.MaxPerCore > 0 {
floor := 0
if config.Min != nil {
floor = int(*config.Min)
}
scaled := int(*config.MaxPerCore) * detectNumCPU()
if scaled > floor {
logrus.Debugf("getConntrackMax: using scaled conntrack-max-per-core")
return scaled
}
logrus.Debugf("getConntrackMax: using conntrack-min")
return floor
}
return 0
}
// detectNumCPU is also cribbed from kube-proxy
func detectNumCPU() int {
// try get numCPU from /sys firstly due to a known issue (https://github.com/kubernetes/kubernetes/issues/99225)
_, numCPU, err := machine.GetTopology(sysfs.NewRealSysFs())
if err != nil || numCPU < 1 {
return runtime.NumCPU()
}
return numCPU
}