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<!DOCTYPE HTML>
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<title>kube-proxy 源码分析 · 田飞雨</title>
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<li>
<a href="https://blog.tianfeiyu.com" target="_blank" class="custom-link">Home</a>
</li>
<li class="divider"></li>
<li class="chapter " data-level="1.1" data-path="../">
<a href="../">
<b>1.1.</b>
Introduction
</a>
</li>
<li class="chapter " data-level="1.2" data-path="./">
<a href="./">
<b>1.2.</b>
kubernetes
</a>
<ul class="articles">
<li class="chapter " data-level="1.2.1" data-path="kube_apiserver.html">
<a href="kube_apiserver.html">
<b>1.2.1.</b>
kube-apiserver 的设计与实现
</a>
</li>
<li class="chapter " data-level="1.2.2" data-path="apiserver_bootstrap_controller.html">
<a href="apiserver_bootstrap_controller.html">
<b>1.2.2.</b>
kube-apiserver 中 apiserver service 的实现
</a>
</li>
<li class="chapter " data-level="1.2.3" data-path="nodelifecycle_controller.html">
<a href="nodelifecycle_controller.html">
<b>1.2.3.</b>
node controller 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.4" data-path="job_controller.html">
<a href="job_controller.html">
<b>1.2.4.</b>
job controller 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.5" data-path="garbagecollector_controller.html">
<a href="garbagecollector_controller.html">
<b>1.2.5.</b>
garbage collector controller 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.6" data-path="daemonset_controller.html">
<a href="daemonset_controller.html">
<b>1.2.6.</b>
daemonset controller 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.7" data-path="statefulset_controller.html">
<a href="statefulset_controller.html">
<b>1.2.7.</b>
statefulset controller 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.8" data-path="deployment_controller.html">
<a href="deployment_controller.html">
<b>1.2.8.</b>
deployment controller 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.9" data-path="replicaset_controller.html">
<a href="replicaset_controller.html">
<b>1.2.9.</b>
replicaset controller 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.10" data-path="kube_scheduler_process.html">
<a href="kube_scheduler_process.html">
<b>1.2.10.</b>
kube-scheduler 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.11" data-path="kube_scheduler_algorithm.html">
<a href="kube_scheduler_algorithm.html">
<b>1.2.11.</b>
kube-scheduler predicates 与 priorities 调度算法源码分析
</a>
</li>
<li class="chapter " data-level="1.2.12" data-path="kube_scheduler_preempt.html">
<a href="kube_scheduler_preempt.html">
<b>1.2.12.</b>
kube-scheduler 优先级与抢占机制源码分析
</a>
</li>
<li class="chapter " data-level="1.2.13" data-path="k8s_service_theory.html">
<a href="k8s_service_theory.html">
<b>1.2.13.</b>
kubernetes service 原理解析
</a>
</li>
<li class="chapter active" data-level="1.2.14" data-path="kube_proxy_process.html">
<a href="kube_proxy_process.html">
<b>1.2.14.</b>
kube-proxy 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.15" data-path="kube_proxy_iptables.html">
<a href="kube_proxy_iptables.html">
<b>1.2.15.</b>
kube-proxy iptables 模式源码分析
</a>
</li>
<li class="chapter " data-level="1.2.16" data-path="kube_proxy_ipvs.html">
<a href="kube_proxy_ipvs.html">
<b>1.2.16.</b>
kube-proxy ipvs 模式源码分析
</a>
</li>
<li class="chapter " data-level="1.2.17" data-path="kubelet-modules.html">
<a href="kubelet-modules.html">
<b>1.2.17.</b>
kubelet 架构浅析
</a>
</li>
<li class="chapter " data-level="1.2.18" data-path="kubelet_init.html">
<a href="kubelet_init.html">
<b>1.2.18.</b>
kubelet 启动流程分析
</a>
</li>
<li class="chapter " data-level="1.2.19" data-path="kubelet_create_pod.html">
<a href="kubelet_create_pod.html">
<b>1.2.19.</b>
kubelet 创建 pod 的流程
</a>
</li>
<li class="chapter " data-level="1.2.20" data-path="node_status.html">
<a href="node_status.html">
<b>1.2.20.</b>
kubelet 状态上报的方式
</a>
</li>
<li class="chapter " data-level="1.2.21" data-path="k8s_events.html">
<a href="k8s_events.html">
<b>1.2.21.</b>
kubelet 中事件处理机制
</a>
</li>
<li class="chapter " data-level="1.2.22" data-path="kubelet_status_manager.html">
<a href="kubelet_status_manager.html">
<b>1.2.22.</b>
kubelet statusManager 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.23" data-path="kubelet_qos.html">
<a href="kubelet_qos.html">
<b>1.2.23.</b>
kubernetes 中 Qos 的设计与实现
</a>
</li>
<li class="chapter " data-level="1.2.24" data-path="kubelet_garbage_collect.html">
<a href="kubelet_garbage_collect.html">
<b>1.2.24.</b>
kubelet 中垃圾回收机制的设计与实现
</a>
</li>
<li class="chapter " data-level="1.2.25" data-path="k8s_evicted.html">
<a href="k8s_evicted.html">
<b>1.2.25.</b>
kubernetes 中 Evicted pod 是如何产生的
</a>
</li>
<li class="chapter " data-level="1.2.26" data-path="kubernetes_descheduler.html">
<a href="kubernetes_descheduler.html">
<b>1.2.26.</b>
Kubernetes 中 Descheduler 组件的使用与扩展
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="1.3" data-path="../knative/">
<a href="../knative/">
<b>1.3.</b>
knative
</a>
<ul class="articles">
<li class="chapter " data-level="1.3.1" data-path="../knative/deploy_with_minkube.html">
<a href="../knative/deploy_with_minkube.html">
<b>1.3.1.</b>
在 minkube 上部署 knative
</a>
</li>
<li class="chapter " data-level="1.3.2" data-path="../knative/knative_serving.html">
<a href="../knative/knative_serving.html">
<b>1.3.2.</b>
knative serving 组件分析
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="1.4" data-path="../cgroup/">
<a href="../cgroup/">
<b>1.4.</b>
cgroup
</a>
<ul class="articles">
<li class="chapter " data-level="1.4.1" data-path="../cgroup/blkio_cgroup.html">
<a href="../cgroup/blkio_cgroup.html">
<b>1.4.1.</b>
blkio cgroup
</a>
</li>
<li class="chapter " data-level="1.4.2" data-path="../cgroup/pid_cgroup.html">
<a href="../cgroup/pid_cgroup.html">
<b>1.4.2.</b>
pid cgroup
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="1.5" data-path="../go/">
<a href="../go/">
<b>1.5.</b>
go
</a>
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<li class="chapter " data-level="1.5.1" data-path="../go/func_return_value_or_pointer.html">
<a href="../go/func_return_value_or_pointer.html">
<b>1.5.1.</b>
golang 中函数使用值返回与指针返回的区别，底层原理分析
</a>
</li>
<li class="chapter " data-level="1.5.2" data-path="../go/golang_bootstrap.html">
<a href="../go/golang_bootstrap.html">
<b>1.5.2.</b>
Golang 程序启动流程分析
</a>
</li>
<li class="chapter " data-level="1.5.3" data-path="../go/golang_gpm.html">
<a href="../go/golang_gpm.html">
<b>1.5.3.</b>
Golang GPM 模型剖析
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<a href=".." >kube-proxy 源码分析</a>
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<li><a href="#kube-proxy-启动流程">kube-proxy 启动流程</a></li>
<li><a href="#proxier-的初始化">proxier 的初始化</a><ul>
<li><a href="#iptables-proxier-初始化">iptables proxier 初始化</a></li>
<li><a href="#ipvs-proxier-初始化">ipvs proxier 初始化</a></li>
<li><a href="#userspace-proxier-初始化">userspace proxier 初始化</a></li>
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<li><a href="#proxier-接口实现">proxier 接口实现</a><ul>
<li><a href="#handler-的实现">handler 的实现</a></li>
<li><a href="#sync-以及-syncloop-的实现">Sync() 以及 SyncLoop() 的实现</a></li>
</ul>
</li>
<li><a href="#总结">总结</a></li>
</ul>
<p>上篇文章 <a href="https://blog.tianfeiyu.com/2019/10/31/k8s_service_theory/" target="_blank">kubernetes service 原理解析</a> 已经分析了 service 原理以 kube-proxy 中三种模式的原理，本篇文章会从源码角度分析 kube-proxy 的设计与实现。</p>
<blockquote>
<p>kubernetes 版本: v1.16</p>
</blockquote>
<h2 id="kube-proxy-启动流程"><a name="kube-proxy-启动流程" class="anchor-navigation-ex-anchor" href="#kube-proxy-启动流程"><i class="fa fa-link" aria-hidden="true"></i></a>kube-proxy 启动流程</h2>
<p>前面的文章已经说过 kubernetes 中所有组件都是通过其 <code>run()</code> 方法启动主逻辑的，<code>run()</code> 方法调用之前会进行解析命令行参数、添加默认值等。下面就直接看 kube-proxy 的 <code>run()</code> 方法：</p>
<ul>
<li>若启动时指定了 <code>--write-config-to</code> 参数，kube-proxy 只将启动的默认参数写到指定的配置文件中，然后退出</li>
<li>初始化 ProxyServer 对象</li>
<li>如果启动参数 <code>--cleanup</code> 设置为 true，则清理 iptables 和 ipvs 规则并退出</li>
</ul>
<p><code>k8s.io/kubernetes/cmd/kube-proxy/app/server.go:290</code></p>
<pre class="language-"><code>func (o *Options) Run() error {
defer close(o.errCh)
// 1.如果指定了 --write-config-to 参数，则将默认的配置文件写到指定文件并退出
if len(o.WriteConfigTo) > 0 {
return o.writeConfigFile()
}
// 2.初始化 ProxyServer 对象
proxyServer, err := NewProxyServer(o)
if err != nil {
return err
}
// 3.如果启动参数 --cleanup 设置为 true，则清理 iptables 和 ipvs 规则并退出
if o.CleanupAndExit {
return proxyServer.CleanupAndExit()
}
o.proxyServer = proxyServer
return o.runLoop()
}
</code></pre><p><code>Run()</code> 方法中主要调用了 <code>NewProxyServer()</code> 方法来初始化 ProxyServer，然后会调用 <code>runLoop()</code> 启动主循环，继续看初始化 ProxyServer 的具体实现：</p>
<ul>
<li>初始化 iptables、ipvs 相关的 interface</li>
<li>若启用了 ipvs 则检查内核版本、ipvs 依赖的内核模块、ipset 版本，内核模块主要包括：<code>ip_vs</code>，<code>ip_vs_rr</code>,<code>ip_vs_wrr</code>,<code>ip_vs_sh</code>,<code>nf_conntrack_ipv4</code>,<code>nf_conntrack</code>，若没有相关模块，kube-proxy 会尝试使用 <code>modprobe</code> 自动加载</li>
<li>根据 proxyMode 初始化 proxier，kube-proxy 启动后只运行一种 proxier</li>
</ul>
<p><code>k8s.io/kubernetes/cmd/kube-proxy/app/server_others.go:57</code></p>
<pre class="language-"><code>func NewProxyServer(o *Options) (*ProxyServer, error) {
return newProxyServer(o.config, o.CleanupAndExit, o.master)
}
func newProxyServer(
config *proxyconfigapi.KubeProxyConfiguration,
cleanupAndExit bool,
master string) (*ProxyServer, error) {
......
if c, err := configz.New(proxyconfigapi.GroupName); err == nil {
c.Set(config)
} else {
return nil, fmt.Errorf("unable to register configz: %s", err)
}
......
// 1.关键依赖工具 iptables/ipvs/ipset/dbus
var iptInterface utiliptables.Interface
var ipvsInterface utilipvs.Interface
var kernelHandler ipvs.KernelHandler
var ipsetInterface utilipset.Interface
var dbus utildbus.Interface
// 2.执行 linux 命令行的工具
execer := exec.New()
// 3.初始化 iptables/ipvs/ipset/dbus 对象
dbus = utildbus.New()
iptInterface = utiliptables.New(execer, dbus, protocol)
kernelHandler = ipvs.NewLinuxKernelHandler()
ipsetInterface = utilipset.New(execer)
// 4.检查该机器是否支持使用 ipvs 模式
canUseIPVS, _ := ipvs.CanUseIPVSProxier(kernelHandler, ipsetInterface)
if canUseIPVS {
ipvsInterface = utilipvs.New(execer)
}
if cleanupAndExit {
return &ProxyServer{
......
}, nil
}
// 5.初始化 kube client 和 event client
client, eventClient, err := createClients(config.ClientConnection, master)
if err != nil {
return nil, err
}
......
// 6.初始化 healthzServer
var healthzServer *healthcheck.HealthzServer
var healthzUpdater healthcheck.HealthzUpdater
if len(config.HealthzBindAddress) > 0 {
healthzServer = healthcheck.NewDefaultHealthzServer(config.HealthzBindAddress, 2*config.IPTables.SyncPeriod.Duration, recorder, nodeRef)
healthzUpdater = healthzServer
}
// 7.proxier 是一个 interface，每种模式都是一个 proxier
var proxier proxy.Provider
// 8.根据 proxyMode 初始化 proxier
proxyMode := getProxyMode(string(config.Mode), kernelHandler, ipsetInterface, iptables.LinuxKernelCompatTester{})
......
if proxyMode == proxyModeIPTables {
klog.V(0).Info("Using iptables Proxier.")
if config.IPTables.MasqueradeBit == nil {
return nil, fmt.Errorf("unable to read IPTables MasqueradeBit from config")
}
// 9.初始化 iptables 模式的 proxier
proxier, err = iptables.NewProxier(
.......
)
if err != nil {
return nil, fmt.Errorf("unable to create proxier: %v", err)
}
metrics.RegisterMetrics()
} else if proxyMode == proxyModeIPVS {
// 10.判断是够启用了 ipv6 双栈
if utilfeature.DefaultFeatureGate.Enabled(features.IPv6DualStack) {
......
// 11.初始化 ipvs 模式的 proxier
proxier, err = ipvs.NewDualStackProxier(
......
)
} else {
proxier, err = ipvs.NewProxier(
......
)
}
if err != nil {
return nil, fmt.Errorf("unable to create proxier: %v", err)
}
metrics.RegisterMetrics()