【kubernetes/k8s概念】CNI源码分析

快来打我* 2022-05-12 04:36 234阅读 0赞

[https://github.com/containernetworking/cni][https_github.com_containernetworking_cni]

# **1、main函数** #

*  配置文件目录netdir，如果未指定，则默认为/etc/cni/net.d
 *  调用libcni.LoadConfList(netdir, os.Args\[2\])，参数os.Args\[2\]为用户指定的的network的名字

func main() {
    	netdir := os.Getenv(EnvNetDir)
    	if netdir == "" {
    		netdir = DefaultNetDir
    	}
    	netconf, err := libcni.LoadConfList(netdir, os.Args[2])
    
    	var capabilityArgs map[string]interface{}
    	capabilityArgsValue := os.Getenv(EnvCapabilityArgs)
    
    	var cniArgs [][2]string
    	args := os.Getenv(EnvCNIArgs)
    	if len(args) > 0 {
    		cniArgs, err = parseArgs(args)
    		if err != nil {
    			exit(err)
    		}
    	}
    
    	netns := os.Args[3]
    
    	cninet := &libcni.CNIConfig{
    		Path: filepath.SplitList(os.Getenv(EnvCNIPath)),
    	}
    
    	rt := &libcni.RuntimeConf{
    		ContainerID:    "cni",
    		NetNS:          netns,
    		IfName:         "eth0",
    		Args:           cniArgs,
    		CapabilityArgs: capabilityArgs,
    	}
    
    	switch os.Args[1] {
    	case CmdAdd:
    		result, err := cninet.AddNetworkList(netconf, rt)
    
    		exit(err)
    	case CmdDel:
    		exit(cninet.DelNetworkList(netconf, rt))
    	}
    }

##     （1）、LoadConfList函数 ##

*  查找是否有以.conflist作为后缀的配置文件，如果有Name和参数os.Args\[2\]一致，返回NetConfigList填充配置。否则，查找是否存在以.conf或.json作为后缀的配置文件。如果存在Name一致的配置，则加载该配置文件。由于.conf或"json中都是单个的网络配置，因此需要读取包不返回一个NetConfig的NetworkConfigList

func LoadConfList(dir, name string) (*NetworkConfigList, error) {
    	files, err := ConfFiles(dir, []string{".conflist"})
    	if err != nil {
    		return nil, err
    	}
    	sort.Strings(files)
    
    	for _, confFile := range files {
    		conf, err := ConfListFromFile(confFile)
    		if err != nil {
    			return nil, err
    		}
    		if conf.Name == name {
    			return conf, nil
    		}
    	}
    
    	// Try and load a network configuration file (instead of list)
    	// from the same name, then upconvert.
    	singleConf, err := LoadConf(dir, name)
    	if err != nil {
    		// A little extra logic so the error makes sense
    		if _, ok := err.(NoConfigsFoundError); len(files) != 0 && ok {
    			// Config lists found but no config files found
    			return nil, NotFoundError{dir, name}
    		}
    
    		return nil, err
    	}
    	return ConfListFromConf(singleConf)
    }

## （2）、NetworkConfigList结构体   ##

type NetworkConfig struct {
    	Network *types.NetConf
    	Bytes   []byte
    }
    
    type NetworkConfigList struct {
    	Name       string
    	CNIVersion string
    	Plugins    []*NetworkConfig
    	Bytes      []byte
    }

## （3）、NetConf结构体 ##

// NetConf describes a network.
    type NetConf struct {
    	CNIVersion string `json:"cniVersion,omitempty"`
    
    	Name         string          `json:"name,omitempty"`
    	Type         string          `json:"type,omitempty"`
    	Capabilities map[string]bool `json:"capabilities,omitempty"`
    	IPAM         struct {
    		Type string `json:"type,omitempty"`
    	} `json:"ipam,omitempty"`
    	DNS DNS `json:"dns"`
    }

## （4）、RuntimeConf结构体 ##

容器运行时信息的数据结构

type RuntimeConf struct {
    	ContainerID string
    	NetNS       string
    	IfName      string
    	Args        [][2]string
    	// A dictionary of capability-specific data passed by the runtime
    	// to plugins as top-level keys in the 'runtimeConfig' dictionary
    	// of the plugin's stdin data.  libcni will ensure that only keys
    	// in this map which match the capabilities of the plugin are passed
    	// to the plugin
    	CapabilityArgs map[string]interface{}
    }

## （5）、AddNetworkList函数 ##

*  根据容器网络配置信息和容器运行时信息，执行加入容器网络的操作

// AddNetworkList executes a sequence of plugins with the ADD command
    func (c *CNIConfig) AddNetworkList(list *NetworkConfigList, rt *RuntimeConf) (types.Result, error) {
    	var prevResult types.Result
    	for _, net := range list.Plugins {
    		pluginPath, err := invoke.FindInPath(net.Network.Type, c.Path)
    		if err != nil {
    			return nil, err
    		}
    
    		newConf, err := buildOneConfig(list, net, prevResult, rt)
    		if err != nil {
    			return nil, err
    		}
    
    		prevResult, err = invoke.ExecPluginWithResult(pluginPath, newConf.Bytes, c.args("ADD", rt))
    		if err != nil {
    			return nil, err
    		}
    	}
    
    	return prevResult, nil
    }

## **2、**libcni ##

[cni][https_github.com_containernetworking_cni]项目提供了一个library，定义了集成cni插件的接口libcni。Interface定义如下：

type CNI interface {
    	AddNetworkList(net *NetworkConfigList, rt *RuntimeConf) (types.Result, error)
    	DelNetworkList(net *NetworkConfigList, rt *RuntimeConf) error
    
    	AddNetwork(net *NetworkConfig, rt *RuntimeConf) (types.Result, error)
    	DelNetwork(net *NetworkConfig, rt *RuntimeConf) error
    }

[https_github.com_containernetworking_cni]: https://github.com/containernetworking/cni