Kubernetes网络框架
// cmd/kubelet/app/server.go-1、func UnsecuredKubeletDeps(s *options.KubeletServer) (*kubelet.KubeletDeps, error)
[*]....
[*]最后调用return &kubelet.KubeletDeps {
....
NetworkPlugins: ProbeNetworkPlugins(s.NetworkPluginDir, s.CNIConfDir, s.CNIBinDir),
....
}
// cmd/kubelet/app/plugins.go
// ProbeNetworkPlugins collects all compiled-in plugins
0、func ProbeNetworkPlugins(pluginDir, cniConfDir, cniBinDir string) []network.NetworkPlugin
[*]创建allPlugins := []network.NetworkPlugin{}
[*]若cniConfDir为""，则设置cniConfDir为pluginDir
[*]最后调用allPlugins = append(allPlugins, cni.ProbeNetworkPlugins(cniConfDir, cniBinDir)...) ---> cni.ProbeNetworkPlugins()返回一个cniNetworkPlugin为实例的NetworkPlugin接口
[*]allPlugins = append(allPlugins, kubenet.NewPlugin(pluginDir))
// pkg/kubelet/kubelet.go
// NewMainKubelet instantiates a new Kubelet object along with the required internal modules.
// No initialization of Kubelet and its modules should happen here.
1、func NewMainKubelet(kubeCfg *componentconfig.KubeletConfiguraion, kubeDeps *KubeletDeps, standaloneMode bool) (*Kubelet, error)
[*]......
[*]调用mode, err := effectiveHairpinMode(componentconfig.HairpinMode(kubeCfg.HairpinMode), kubeCfg.ContainerRuntime, kubeCfg.NetworkPluginName)
[*]调用plug, err := network.InitNetworkPlugin(kubeDeps.NetworkPlugins, kubeCfg.NetworkPluginName, &criNetworkHost{&networkHost{klet}, &network.NoopPortMappingGetter{}}, klet.hairpinMode, klet.nonMasqueradeCIDR, int(kubeCfg.NetworkPluginMTU))
[*]设置binDir := kubeCfg.CNIBinDir，若binDir为""，则设置binDir = kubeCfg.NetworkPluginDir
[*]设置pluginSettings := dockershim.NetworkPluginSettings{
HairpinMode: klet.hairpinMode,
NonMasqueradeCIDR: klet.nonMasqueradeCIDR,
PluginName: kubeCfg.NetworkPluginName,
PluginConfDir: kubeCfg.CNIConfDir,
PluginBinDir: binDir,
MTU: int(kubeCfg.NetworkPluginMTU),
}
[*]当kubeCfg.ContainerRuntime != "rkt"并且kubeCfg.EnableCRI时：
[*]设置klet.networkPlugin = nil --> kubelet defers to the runtime shim to setup networking
[*]否则，当kubeCfg.ContainerRuntime为"docker"时，创建runtime := dockertools.NewDockerManager(
...
klet.networkPlugin,
// If using "kubenet", the Kubernetes network plugin that wraps CNI's bridge plugin, it knows how
// to set the hairpin veth flag so we tell the container runtime to back away from setting it.If the
// kubelet is started with any other plugin we can't sure it handles the hairpin case so we instruct
// the docker runtime to set the flag instead.
klet.hairpinMode == componentconfig.HairpinVeth && kubeCfg.NetworkPluginName != "kubenet",
...
)
Host, NamespaceGetter, PortMappingGetter结构如下所示：
// Host is an interface that plugins can use to access the kubelet.Plugins, other than kubenet, only require
// a way to access namespace information and port mapping information, which they can do directly through
// the embeded interfaces.
type Host interface {
// NamespaceGetter is a getter for sandbox information.
NamespaceGetter
// PortMappingGetter is a getter for sandbox port mapping information.
PortMappingGetter
// LegacyHost contains methods that trap back into the Kubelet. Dependence
// *do not* add more dependencies in this interface. In a post-cri world,
// network plugins will be invoked by the runtime shim, and should only
// require GetNetNS and GetPodPortMappings.
LegacyHost
}
// NamespaceGetter is an interface to retrieve namespace information for a given
// sandboxID. Typically implemented by runtime shims that are closely coupled to
// CNI plugin wrappers like kubenet.
type NamespaceGetter interface {
// GetNetNS returns network namespace information for the given containerID
GetNetNS(containerID string) (string, error)
}
// PortMappingGetter is an interface to retrieve port mapping information for a given
// sandboxID. Typically implemented by runtime shims that are closely coupled to CNI
// plugin wrappers like kubenet.
type PortMappingGetter interface {
// GetPodPortMappings returns sandbox port mappings information.
GetPodPortMappings(containerID string) ([]*hostport.PortMapping, error)
}
// pkg/kubelet/network/plugins.go
// InitNetworkPlugin inits the plugin that matches networkPluginName. Plugins must have unique names.
2、func InitNetworkPlugin(plugins []NetworkPlugin, networkPluginName string, host Host, hairpinMode componentconfig.HairpinMode, nonMasqueradeCIDR string, mtu int) (NetworkPlugin, error)
[*]当networkPluginName为""时，默认设置plugin := &NoopNetworkPlugin{}，再调用plug.Init(host, hairpinMode, nonMasqueradeCIDR，mtu)并返回return plug, nil
[*]否则创建pluginMap := mapNetworkPlugin{}，遍历plugins，将plugins都插入到pluginMap中
[*]创建chosenPlugin := pluginMap，若chosenPlugin不为nil，调用chosenPlugin.Init(host, hairpinMode, nonMasqueradeCIDR, mtu)
------------------------------------------------------- 以cni plugin作为例子 -------------------------------------------------------------------
// pkg/kubelet/network/cni/cni.go
func (plugin *cniNetworkPlugin) Init(host network.Host, hairpinMode componentconfig.HairpinMode, nonMasqueradeCIDR string, mtu int) error
[*]调用plugin.nsenterPath, err = plugin.execer.LookPath("nsenter")
[*]将plugin.host赋值为host
[*]创建一个goroutine，每隔十分钟，调用plugin.syncNetworkConfig()周期性地来检测network config的更新
cniNetworkPlugin数据结构如下：
type cniNetworkPlugin struct {
network.NoopNetworkPlugin
loNetwork *cniNetwork
sync.RWMutex
defaultNetwork *cniNetwork
host network.Host
execer utilexec.Interface
nsenterPath string
pluginDir string
binDir string
VendorCNIDirPrefix string
}
// pkg/kubelet/network/cni/cni.go
func (plugin *cniNetworkPlugin) SetUpPod(namespace string, name string,>
[*]首先调用plugin.checkInitialized()判断plugin是否初始化完成
[*]调用netnsPath, err := plugin.host.GetNetNS(id.ID)获取namespace对应的net ns的路径
[*]调用_, err = plugin.loNetwork.addToNetwork(name, namespace,>调用_, err = plugin.getDefaultNetwork().addToNetwork(name, namespace,>
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