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源码地址：https://github.com/k8snetworkplumbingwg/multus-cni.git 源码解析
解析之前，先看下机器上的/opt/cni/bin目录下的可执行文件，这些文件都有可能被cni插件调用：
[root@zhounanjun-test01 ~]# ls /opt/cni/bin/
bandwidth calico dhcp flannel host-local kube-ovn macvlan portmap sbr static vlan
bridge calico-ipam firewall host-device ipvlan loopback multus ptp sriov tuning whereabouts
这些 CNI 的基础可执行文件，按照功能可以分为以下三类：
第一类，叫做 Main 插件，它是用来创建具体网络设备的二进制文件。比如，bridge（网桥设备）、ipvlan、loopback（lo设备）、macvlan、ptp（Veth Pari 设备）、以及 vlan。第二类，叫做 IPAM（IP Address Management）插件，它是负责分配 IP 地址的二进制文件。比如 dhcp 会向 DHCP 服务器发起请求；host-local 会使用预先配置的 IP 地址段来进行分配；calico-ipam是clalico cni自己的ip地址分配插件，是一种集中式ip分配插件；whereabouts也是一个集中式ip分配插件，用的比较少，我也是因为使用了sriov设备才用到的，所以节点上有这个文件， 这个是k8snetworkplumbingwg社区开源的。 第三类，是由 CNI 社区维护的内置 CNI 插件，比如 flannel，这就是专门为 Flannel 项目提供的 CNI 插件；tunning，是一个通过 sysctl 调整网络设备参数的二进制文件；portmap 是一个通过 iptables 配置端口映射的二进制文件；bandwidth 是一个使用 Token Bucket Filter（TBF）来进行限流的二进制文件；calico是专门为Calico项目提供的CNI插件。 cmdAdd解析源码解析的过程，也就是实现cni插件的过程，希望读者在本文解析后可以实现自己的cni插件。
multus-cni插件的启动代码在cmd/main.go文件中
main函数如下：
func main() {
// Init command line flags to clear vendored packages' one, especially in init()
flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
// add version flag
versionOpt := false
flag.BoolVar(&versionOpt, "version", false, "Show application version")
flag.BoolVar(&versionOpt, "v", false, "Show application version")
flag.Parse()
if versionOpt == true {
fmt.Printf("%s\n", multus.PrintVersionString())
return
}
skel.PluginMain( // 实现cni插件的三个函数cmdAdd, cmdCheck, cmdDel
func(args *skel.CmdArgs) error {
// 用于创建容器时构建网络环境
result, err := multus.CmdAdd(args, nil, nil)
if err != nil {
return err
}
return result.Print()
},
func(args *skel.CmdArgs) error {
return multus.CmdCheck(args, nil, nil)
},
// 用于删除容器时回收 网络环境
func(args *skel.CmdArgs) error { return multus.CmdDel(args, nil, nil) },
cniversion.All, "meta-plugin that delegates to other CNI plugins")
}
skel.PluginMain中传入的三个函数类型，就是cmdAdd, cmdCheck, cmdDel函数。那么先看cmdAdd函数，就是下面这段：
func(args *skel.CmdArgs) error {
// 用于创建容器时构建网络环境
result, err := multus.CmdAdd(args, nil, nil)
if err != nil {
return err
}
return result.Print()
}
调用的是multus.CmdAdd，multus.CmdAdd函数的内容如下，稍加缩减：
func CmdAdd(args *skel.CmdArgs, exec invoke.Exec, kubeClient *k8s.ClientInfo) (cnitypes.Result, error) {
// 是/etc/cni/net.d/00-multus.conf文件的配置
n, err := types.LoadNetConf(args.StdinData) // 从stdinData中反序列化配置，
logging.Debugf("CmdAdd: %v, %v, %v", args, exec, kubeClient)
if err != nil {
return nil, cmdErr(nil, "error loading netconf: %v", err)
}
// 生成client
kubeClient, err = k8s.GetK8sClient(n.Kubeconfig, kubeClient)
if err != nil {
return nil, cmdErr(nil, "error getting k8s client: %v", err)
}
k8sArgs, err := k8s.GetK8sArgs(args) // 参数中包含的是kubelet传递过来的pod信息，比如pod名称，pod所属的namespace等信息
if err != nil {
return nil, cmdErr(nil, "error getting k8s args: %v", err)
}
...
pod, err := getPod(kubeClient, k8sArgs, false) // 从k8s获取pod对象
if err != nil {
return nil, err
}
...
// 获取/etc/cni/net.d/00-multus.conf 配置中的delegates字段数据，该字段中放着的是默认cni插件的配置，比如calico的
// 这个函数深入看下，适用于获取pod要使用的网络插件信息的，可能存在多个网络插件要使用。
_, kc, err := k8s.TryLoadPodDelegates(pod, n, kubeClient, resourceMap) // n中的Delegates数组已经更新完毕
if err != nil {
return nil, cmdErr(k8sArgs, "error loading k8s delegates k8s args: %v", err)
}
// cache the multus config 将Delegates数组内容保存在CNIDir中,
// CNIDir默认路径是：/var/lib/cni/multus
if err := saveDelegates(args.ContainerID, n.CNIDir, n.Delegates); err != nil {
return nil, cmdErr(k8sArgs, "error saving the delegates: %v", err)
}
var result, tmpResult cnitypes.Result
var netStatus []nettypes.NetworkStatus
cniArgs := os.Getenv("CNI_ARGS")
for idx, delegate := range n.Delegates { // 遍历Delegates
ifName := getIfname(delegate, args.IfName, idx) // 获取网卡名称
// 为delegate创建RuntimeConf
rt, cniDeviceInfoPath := types.CreateCNIRuntimeConf(args, k8sArgs, ifName, n.RuntimeConfig, delegate)
if cniDeviceInfoPath != "" && delegate.ResourceName != "" && delegate.DeviceID != "" {
err = nadutils.CopyDeviceInfoForCNIFromDP(cniDeviceInfoPath, delegate.ResourceName, delegate.DeviceID)
// Even if the filename is set, file may not be present. Ignore error,
// but log and in the future may need to filter on specific errors.
if err != nil {
logging.Debugf("cmdAdd: CopyDeviceInfoForCNIFromDP returned an error - err=%v", err)
}
}
netName := ""
// 调用被delegate的cni插件
tmpResult, err = delegateAdd(exec, kubeClient, pod, ifName, delegate, rt, n, cniArgs)
if err != nil {
// If the add failed, tear down all networks we already added
netName = delegate.Conf.Name
if netName == "" {
netName = delegate.ConfList.Name
}
// Ignore errors; DEL must be idempotent anyway
_ = delPlugins(exec, nil, args, k8sArgs, n.Delegates, idx, n.RuntimeConfig, n)
return nil, cmdPluginErr(k8sArgs, netName, "error adding container to network %q: %v", netName, err)
}
// 。。。省略部分设置默认网关的代码
// create the network status, only in case Multus as kubeconfig
if n.Kubeconfig != "" && kc != nil {
if !types.CheckSystemNamespaces(string(k8sArgs.K8S_POD_NAME), n.SystemNamespaces) {
// 根据tmpResult创建delegateNetStatus
delegateNetStatus, err := nadutils.CreateNetworkStatus(tmpResult, delegate.Name, delegate.MasterPlugin, devinfo)
if err != nil {
return nil, cmdErr(k8sArgs, "error setting network status: %v", err)
}
netStatus = append(netStatus, *delegateNetStatus)
}
} else if devinfo != nil {
// Warn that devinfo exists but could not add it to downwards API
logging.Errorf("devinfo available, but no kubeConfig so NetworkStatus not modified.")
}
}
// set the network status annotation in apiserver, only in case Multus as kubeconfig
if n.Kubeconfig != "" && kc != nil {
if !types.CheckSystemNamespaces(string(k8sArgs.K8S_POD_NAME), n.SystemNamespaces) {
// netStatus写入pod注解即在pod的注解中写入pod的ip地址信息
err = k8s.SetNetworkStatus(kubeClient, k8sArgs, netStatus, n)
if err != nil {
if strings.Contains(err.Error(), "failed to query the pod") {
return nil, cmdErr(k8sArgs, "error setting the networks status, pod was already deleted: %v", err)
}
return nil, cmdErr(k8sArgs, "error setting the networks status: %v", err)
}
}
}
return result, nil // 返回cni插件调用结果
}
mdAdd函数的逻辑见下方的流程图：
逻辑讲解：
首先解析参数，生成NetConf对象;根据NetConf中的kubeconfig文件的地址生成k8s client;k8s.GetK8sArgs获取传递进来的pod参数，比如containerID，network namesapce等信息；获取集群中的该pod最重要的一步k8s.TryLoadPodDelegates，该函数用于获取pod要使用的网络插件信息的，可能存在多个网络插件要使用，如果你看过/etc/cni/net.d/00-multus.conf 文件的内容，就知道该文件中Delegates字段存储的数据就是默认cni插件的信息，后面例子中会讲到这个文件，该函数的逻辑就是从00-multus.conf 中获取Delegates的cni插件信息放入NetConf对象的Delegates数组，然后再获取pod注解中k8s.v1.cni.cncf.io/networks字段指明的network-attachment-definition对象的信息放入NetConf对象的Delegates数组；保存Delegates数组到本地的CNIDir目录，默认该目录在/var/lib/cni/multus下然后遍历NetConf对象的Delegates数组，执行每个Delegate中装载的插件的Add方法，其实就是调用每个插件为容器完成容器网络环境构造；将执行结果比如pod的ip信息更新在pod的注解中；设置容器的默认网关；返回执行结果。注意：delegate 意思是，这个 CNI 插件并不会自己做某些事情，而是会调用 Delegate 指定的某种内置插件来完成。
cmdDel解析multus.CmdDel函数：
func CmdDel(args *skel.CmdArgs, exec invoke.Exec, kubeClient *k8s.ClientInfo) error {
// 加载配置
in, err := types.LoadNetConf(args.StdinData)
logging.Debugf("CmdDel: %v, %v, %v", args, exec, kubeClient)
if err != nil {
return err
}
...
k8sArgs, err := k8s.GetK8sArgs(args) // 获取传递来的pod信息
if err != nil {
return cmdErr(nil, "error getting k8s args: %v", err)
}
...
kubeClient, err = k8s.GetK8sClient(in.Kubeconfig, kubeClient) // 生成client
if err != nil {
return cmdErr(nil, "error getting k8s client: %v", err)
}
pod, err := getPod(kubeClient, k8sArgs, true) // 获取pod
if err != nil {
return err
}
// Read the cache to get delegates json for the pod
netconfBytes, path, err := consumeScratchNetConf(args.ContainerID, in.CNIDir) // 读取保存在本地的delegates文件
if err != nil {
// Fetch delegates again if cache is not exist and pod info can be read
// 去找00-multus.conf文件
if os.IsNotExist(err) && pod != nil {
if in.ClusterNetwork != "" {
_, err = k8s.GetDefaultNetworks(pod, in, kubeClient, nil)
if err != nil {
return cmdErr(k8sArgs, "failed to get clusterNetwork/defaultNetworks: %v", err)
}
// First delegate is always the master plugin
in.Delegates[0].MasterPlugin = true
}
// 找不到本地文件就去pod annotation去找
_, _, err := k8s.TryLoadPodDelegates(pod, in, kubeClient, nil)
if err != nil {
if len(in.Delegates) == 0 {
// No delegate available so send error
return cmdErr(k8sArgs, "failed to get delegates: %v", err)
}
// Get clusterNetwork before, so continue to delete
logging.Errorf("Multus: failed to get delegates: %v, but continue to delete clusterNetwork", err)
}
} else {
// The options to continue with a delete have been exhausted (cachefile + API query didn't work)
// We cannot exit with an error as this may cause a sandbox to never get deleted.
logging.Errorf("Multus: failed to get the cached delegates file: %v, cannot properly delete", err)
return nil
}
} else {
defer os.Remove(path)
if err := json.Unmarshal(netconfBytes, &in.Delegates); err != nil {
return cmdErr(k8sArgs, "failed to load netconf: %v", err)
}
// check plugins field and enable ConfListPlugin if there is
for _, v := range in.Delegates {
if len(v.ConfList.Plugins) != 0 {
v.ConfListPlugin = true
}
}
// First delegate is always the master plugin
in.Delegates[0].MasterPlugin = true
}
// set CNIVersion in delegate CNI config if there is no CNIVersion and multus conf have CNIVersion.
for _, v := range in.Delegates { // 遍历Delegates
if v.ConfListPlugin == true && v.ConfList.CNIVersion == "" && in.CNIVersion != "" {
v.ConfList.CNIVersion = in.CNIVersion
v.Bytes, err = json.Marshal(v.ConfList)
if err != nil {
// error happen but continue to delete
logging.Errorf("Multus: failed to marshal delegate %q config: %v", v.Name, err)
}
}
}
// 遍历Delegates，执行回收动作
return delPlugins(exec, pod, args, k8sArgs, in.Delegates, len(in.Delegates)-1, in.RuntimeConfig, in)
}
cmdDel的逻辑流程图如下：
具体逻辑：
kubelet调用multus-cni插件删除容器网络环境；调用到cmdDel函数解析并生成netconf对象生成client,获取pod详情获取本地保存下来的delegates文件（若获取不到就去本地加载00-multus.conf文件和pod 注解中的network-attachment-definition的对象）遍历调用delegates数组中的cni插件，执行插件的cmdDel方法；返回结果。 一个ipvlan的例子在部署完multus-cni后:
[root@zhounanjun-test01 ~]# cat /etc/cni/net.d/00-multus.conf
{ "cniVersion": "0.3.1", "name": "multus-cni-network", "type": "multus", "capabilities": {"portMappings": true}, "kubeconfig": "/etc/cni/net.d/multus.d/multus.kubeconfig", "delegates": [ { "name":"kube-ovn", "cniVersion":"0.3.1", "plugins":[ { "type":"kube-ovn", "server_socket":"/run/openvswitch/kube-ovn-daemon.sock" }, { "type":"portmap", "capabilities":{ "portMappings":true } } ] } ] }
json的内容如下：
{
"cniVersion":"0.3.1",
"name":"multus-cni-network",
"type":"multus",
"capabilities":{
"portMappings":true
},
"kubeconfig":"/etc/cni/net.d/multus.d/multus.kubeconfig",
"delegates":[
{
"name":"kube-ovn",
"cniVersion":"0.3.1",
"plugins":[
{
"type":"kube-ovn",
"server_socket":"/run/openvswitch/kube-ovn-daemon.sock"
},
{
"type":"portmap",
"capabilities":{
"portMappings":true
}
}
]
}
]
}
重点看delegates。对于 multus来说，它调用的 Delegata 插件是 kube-ovn插件，集群中使用的是kube-ovn网络。
创建network-attachment-definition对象,指定main插件使用ipvlan，ipam插件使用host-local，子网cidr是192.168.133.0/24，这边还用了一个sbr的插件，由于我们需要给pod使用双网卡，两张网卡使用的网段可能一样，就会导致pod中往外出去的流量不知道从哪张网卡出去，要是从网卡1进来的数据从网卡2出去，会导致丢包问题，所以使用了sbd插件，他可以做到从哪张网卡进来的流量从哪张网卡出去：
apiVersion: "k8s.cni.cncf.io/v1"
kind: NetworkAttachmentDefinition
metadata:
name: ipvlan-net2
spec:
config: '{
"cniVersion": "0.3.1",
"name": "ipvlan-network",
"plugins": [
{
"type": "ipvlan",
"master": "bond0",
"ipam": {
"type": "host-local",
"subnet": "192.168.133.0/24",
"rangeStart": "192.168.133.190",
"rangeEnd": "192.168.133.250"
}
},
{
"type": "sbr"
}
]
}'
创建测试pod:
apiVersion: v1
kind: Pod
metadata:
name: ipvlanpod22
labels:
environment: production
app: MyApp
annotations:
k8s.v1.cni.cncf.io/networks: ipvlan-net2 # 指定使用的nad对象
spec:
containers:
- name: appcntr1
image: busybox:latest
imagePullPolicy: IfNotPresent
command:
- tail
- -f
- /dev/null
查看pod是否正常运行：
[root@zhounanjun-test01 ipvlan-tests]# kubectl get po
NAME READY STATUS RESTARTS AGE
ipvlanpod22 1/1 Running 0 10s
[root@zhounanjun-test01 ~]# kubectl exec -ti ipvlanpod22 -- ip a
1: lo: mtu 65536 qdisc noqueue qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: net1@if6: mtu 1500 qdisc noqueue
link/ether 14:18:77:46:1a:5a brd ff:ff:ff:ff:ff:ff
inet 192.168.133.190/24 brd 192.168.133.255 scope global net1
valid_lft forever preferred_lft forever
inet6 fe80::1418:7700:146:1a5a/64 scope link
valid_lft forever preferred_lft forever
4399: eth0@if4400: mtu 1400 qdisc noqueue
link/ether 00:00:00:88:33:40 brd ff:ff:ff:ff:ff:ff
inet 10.222.90.214/16 brd 10.222.255.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fd00:10:16::108/64 scope global
valid_lft forever preferred_lft forever
inet6 fe80::200:ff:fe88:3340/64 scope link
valid_lft forever preferred_lft forever
[root@zhounanjun-test01 ipvlan-tests]# docker ps | grep ipvlan
c4aa9fe87ed3 1a80408de790 "tail -f /dev/null" About a minute ago Up About a minute k8s_appcntr1_ipvlapod22_default_d0d41d2f-1240-422d-ba48-459c8b718b98_0
e9532b2b15d4 cis-hub-huabei-3.cmecloud.cn/ecloud/pause:3.2 "/pause" About a minute ago Up About a minute k8s_POD_ipvlanpod22_default_d0d41d2f-1240-422d-ba48-459c8b718b98_0
可以看到ipvlanpod22已经在running了，进入pod运行ip -a命令查看网络信息，看到pod有三张网卡：lo、net1和eth0。其中lo是本地回环设备，net1是ipvlan的网卡，eth0是集群的默认网卡。
为了找到cmdAdd函数中保存在本地的delegates数组文件，在CNIDir目录下查找到该pod保存的delegates数组信息:
[root@zhounanjun-test01 ipvlan-tests]# cd /var/lib/cni/
[root@zhounanjun-test01 cni]# ls
cache multus networks
[root@zhounanjun-test01 cni]# cd multus/
[root@zhounanjun-test01 multus]# pwd
/var/lib/cni/multus
[root@zhounanjun-test01 multus]# ls
002e834da428059256b942909c80b73abbb4b575e1e300fa02e8e4e61306f237 94a6fcf24bbbea87131fb16cb99d6cd782e811f49d7f6ca2af0c45b9477ce479
09e7407d75f796e83516def4416f0c85545ebbdafb953b2e182ed099562e811d a08e23b9bc6339e50ac71a4262e4962191ad636f0628c3bcfe2dd61820cf1511
0a023efc856995fa806539f582578680323753c290e61f61abf891bf24cce09e bd8a986b9c7e270cd49db0f88ca0cad6447ba6685f24fd01ec47d8769af79e0d
10e56ada914f234e32c03e0f07a634f9e24ebc7ffb0a4d90eaaa28645a18cc87 c38c190069cbe35bba9c9153ef624e2ae82180cc8f10d4aa1e09907c89178bb8
2548fb21a62fa48f41b74d75c5d950e3d5690fc50d14b54d46dd8ad76a2c49f1 cfdbbe7c1ad89851b4bbdbf42f3ccec8ef14f849685b5307e7122bcdea495ea9
325cab7d927103e8f6b30dab6046f2e05daed9497f158e33f8fd960912e58d4a e20b6d7d0bcc635c93820fce418ed628c29c45765d8f949440fde419273b924a
362134fe2218518006a754af6d0509ba76e8095ad43818a67755b51cbd3ac596 e9532b2b15d4d52a14db5326d87348211ba943bc1f61e92d94f04ee167efae72
45ee60bd57ba999f4f419a74136f861fd4b0779d6e0eede1c5bfbb67e0fe0d43 ef92c2c63d52f67a9f561f0f4d8a60eb0f5645bf690030535dac324d668804b4
4d01e982e4413e927b0c85de677b04a70973ca60ed91afca0d1b0f6e27995246 f9832765b5565afa934f0f01f074ba68f4ac8ad63769cc32a4ea40d14c718e0d
8e4c186dc21b455943abf96d49cea0a3caef90c941cfda9167475a37990ddbf2 results
[root@zhounanjun-test01 multus]# cat e9532b2b15d4d52a14db5326d87348211ba943bc1f61e92d94f04ee167efae72
[{"Conf":{"cniVersion":"0.3.1","name":"kube-ovn","ipam":{},"dns":{}},"ConfList":{"cniVersion":"0.3.1","name":"kube-ovn","plugins":[{"type":"kube-ovn","ipam":{},"dns":{}},{"type":"portmap","capabilities":{"portMappings":true},"ipam":{},"dns":{}}]},"Name":"kube-ovn","IsFilterGateway":false,"Bytes":"eyJjbmlWZXJzaW9uIjoiMC4zLjEiLCJuYW1lIjoia3ViZS1vdm4iLCJwbHVnaW5zIjpbeyJzZXJ2ZXJfc29ja2V0IjoiL3J1bi9vcGVudnN3aXRjaC9rdWJlLW92bi1kYWVtb24uc29jayIsInR5cGUiOiJrdWJlLW92biJ9LHsiY2FwYWJpbGl0aWVzIjp7InBvcnRNYXBwaW5ncyI6dHJ1ZX0sInR5cGUiOiJwb3J0bWFwIn1dfQ=="},{"Conf":{"cniVersion":"0.3.1","name":"ipvlan-network","ipam":{},"dns":{}},"ConfList":{"cniVersion":"0.3.1","name":"ipvlan-network","plugins":[{"type":"ipvlan","ipam":{"type":"host-local"},"dns":{}},{"type":"sbr","ipam":{},"dns":{}}]},"Name":"default/ipvlan-net2","IsFilterGateway":false,"Bytes":"eyAiY25pVmVyc2lvbiI6ICIwLjMuMSIsICJuYW1lIjogImlwdmxhbi1uZXR3b3JrIiwgInBsdWdpbnMiOiBbIHsgInR5cGUiOiAiaXB2bGFuIiwgIm1hc3RlciI6ICJib25kMCIsICJpcGFtIjogeyAidHlwZSI6ICJob3N0LWxvY2FsIiwgInN1Ym5ldCI6ICIxOTIuMTY4LjEzMy4wLzI0IiwgInJhbmdlU3RhcnQiOiAiMTkyLjE2OC4xMzMuMTkwIiwgInJhbmdlRW5kIjogIjE5Mi4xNjguMTMzLjI1MCIgfSB9LCB7ICJ0eXBlIjogInNiciIgfSBdIH0="}]
保存下来的json内容如下：
[
{
"Conf":{
"cniVersion":"0.3.1",
"name":"kube-ovn",
"ipam":{
},
"dns":{
}
},
"ConfList":{
"cniVersion":"0.3.1",
"name":"kube-ovn",
"plugins":[
{
"type":"kube-ovn",
"ipam":{
},
"dns":{
}
},
{
"type":"portmap",
"capabilities":{
"portMappings":true
},
"ipam":{
},
"dns":{
}
}
]
},
"Name":"kube-ovn",
"IsFilterGateway":false,
"Bytes":"eyJjbmlWZXJzaW9uIjoiMC4zLjEiLCJuYW1lIjoia3ViZS1vdm4iLCJwbHVnaW5zIjpbeyJzZXJ2ZXJfc29ja2V0IjoiL3J1bi9vcGVudnN3aXRjaC9rdWJlLW92bi1kYWVtb24uc29jayIsInR5cGUiOiJrdWJlLW92biJ9LHsiY2FwYWJpbGl0aWVzIjp7InBvcnRNYXBwaW5ncyI6dHJ1ZX0sInR5cGUiOiJwb3J0bWFwIn1dfQ=="
},
{
"Conf":{
"cniVersion":"0.3.1",
"name":"ipvlan-network",
"ipam":{
},
"dns":{
}
},
"ConfList":{
"cniVersion":"0.3.1",
"name":"ipvlan-network",
"plugins":[
{
"type":"ipvlan",
"ipam":{
"type":"host-local"
},
"dns":{
}
},
{
"type":"sbr",
"ipam":{
},
"dns":{
}
}
]
},
"Name":"default/ipvlan-net2",
"IsFilterGateway":false,
"Bytes":"eyAiY25pVmVyc2lvbiI6ICIwLjMuMSIsICJuYW1lIjogImlwdmxhbi1uZXR3b3JrIiwgInBsdWdpbnMiOiBbIHsgInR5cGUiOiAiaXB2bGFuIiwgIm1hc3RlciI6ICJib25kMCIsICJpcGFtIjogeyAidHlwZSI6ICJob3N0LWxvY2FsIiwgInN1Ym5ldCI6ICIxOTIuMTY4LjEzMy4wLzI0IiwgInJhbmdlU3RhcnQiOiAiMTkyLjE2OC4xMzMuMTkwIiwgInJhbmdlRW5kIjogIjE5Mi4xNjguMTMzLjI1MCIgfSB9LCB7ICJ0eXBlIjogInNiciIgfSBdIH0="
}
]
对于之前cmdAdd函数解析的部分，会保存容器的delegates数组到本地文件，delegates数组中包含两个网络，第一个是kube-ovn网络，第二个是ipvlan-network。这样就和上面的
总结本文主要讲了multus-cni的代码解析,并根据代码解析，现场验证了ipvlan的例子，并在例子中介绍了几个关键的文件。实现cni就是实现cmdAdd、cmdDel和cmdCheck方法，然后根据需要在cmdAdd中使用已有的main插件和ipam插件，当然main插件和ipam插件可以自己实现，并不一定要用已有的插件。其实multus-cni虽然满足k8s的容器网络接口的规范，但是其并不是真正的cni实体，他会最终调用了delegates数组里使用的cni插件，所以，严格来讲，他是cni插件的管理者。要想学习真正的cni插件最好还是看看calico这种项目，能学到更多的东西。
参考文章：
[1] https://blog.crazytaxii.com/posts/multus_cni/
[2] https://www.cni.dev/plugins/current/ipam/host-local/
[3] http://119.23.219.145/posts/kubernetes-cni-%E7%9A%84%E5%9F%BA%E6%9C%AC%E5%8E%9F%E7%90%86/
[4] https://access.redhat.com/documentation/zh-cn/openshift_container_platform/4.3/html/networking/multiple-networks
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