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2022-08-08
KubeEdge源码分析之(七)edgemesh(kubeedge demo)
本文对edgecore的edgemesh模块进行剖析,kubeedge官网目前没有edgemesh相关介绍,根据华为近期的边缘计算视频分享课程获得edgemsh的相关信息。edgemesh作为edgecore中节点级别的代理解决方案,主要实现了节点内的流量代理、节点间的流量代理和节点内的DNS解析3块功能,本文就来剖析这三块功能的具体实现:
edgemesh Struct组成及注册
edgemesh业务逻辑剖析
edgemesh Struct组成及注册
从edgemesh模块的注册函数入手:
kubeedge/edgemesh/pkg/module.go
// Register register edgemesh func Register() { core.Register(&EdgeMesh{}) }
注册函数只干了一件事,就是将实例化的edgemesh struct加入到一个全局map中去,进入EdgeMesh struct的定义:
kubeedge/edgemesh/pkg/module.go
//EdgeMesh defines EdgeMesh object structure type EdgeMesh struct { context *context.Context }
EdgeMesh struct的定义比较简单,只有context一个属性,该属性用来与edgecore中的其他模块进行通信,具体可以参考kubeedge源码分析系列之cloudcore中的“cloudcore功能模块之间通信的消息框架”部分,本文就不对其进行展开剖析。
edgemesh业务逻辑剖析
从edgemesh模块的启动函数入手:
kubeedge/edgemesh/pkg/module.go
//Start sets context and starts the controller func (em *EdgeMesh) Start(c *context.Context) { em.context = c proxy.Init() go server.Start() // we need watch message to update the cache of instances for { if msg, ok := em.context.Receive(constant.ModuleNameEdgeMesh); ok == nil { proxy.MsgProcess(msg) klog.Infof("get message: %v", msg) continue } } }
启动函数Start(...)做了如下几件事:
1. 接收并保存通信管道
em.context = c
2. 初始化porxy
proxy.Init()
3. 启动服务
go server.Start()
4. 通过一个for循环接收通信管道中关于edgemesh的信息并处理
for {...}
下面对 “2. 初始化porxy”、“3. 启动服务”和“4. 通过一个for循环接收通信管道中关于edgemesh的信息并处理”展开剖析。
初始化porxy
进入proxy.Init()定义:
kubeedge/edgemesh/pkg/proxy/proxy.go
// Init: init the proxy. create virtual device and assign ips, etc..func Init() { go func() { unused = make([]string, 0) addrByService = &addrTable{} c := context.GetContext(context.MsgCtxTypeChannel) metaClient = client.New(c) //create virtual network device for { err := vdev.CreateDevice() if err == nil { break } klog.Warningf("[L4 Proxy] create Device is failed : %s", err) //there may have some exception need to be fixed on OS time.Sleep(2 * time.Second) } //configure vir ip ipPoolSize = 0 expandIpPool() //open epoll ep, err := poll.CreatePoll(pollCallback) if err != nil { vdev.DestroyDevice() klog.Errorf("[L4 Proxy] epoll is open failed : %s", err) return } epoll = ep go epoll.Loop() klog.Infof("[L4 Proxy] proxy is running now") }()}
Init()函数主要做3块事情:
1. 创建获得pod原数据的client
unused = make([]string, 0) addrByService = &addrTable{} c := context.GetContext(context.MsgCtxTypeChannel) metaClient = client.New(c)
2.创建和维护虚拟网络设备
//create virtual network device for { err := vdev.CreateDevice() if err == nil { break } klog.Warningf("[L4 Proxy] create Device is failed : %s", err) //there may have some exception need to be fixed on OS time.Sleep(2 * time.Second) } //configure vir ip ipPoolSize = 0 expandIpPool()
3. 通过epoll管理代理进程
//open epollep, err := poll.CreatePoll(pollCallback) if err != nil { vdev.DestroyDevice() klog.Errorf("[L4 Proxy] epoll is open failed : %s", err) return } epoll = ep go epoll.Loop()klog.Infof("[L4 Proxy] proxy is running now")
进入创建虚拟网络设备的定义vdev.CreateDevice():
kubeedge/edgemesh/pkg/proxy/virtualdevice/virtualdevice.go
func CreateDevice() error { //if device is exist,delete and create a new one //make sure the latest configuration DestroyDevice() edge0 := &netlink.Dummy{ LinkAttrs: netlink.LinkAttrs{ Name: DeviceNameDefault, }, } return nh.LinkAdd(edge0) }
CreateDevice()函数先判断虚拟网络设备edge0是否存在,如果存在就将其删除并重建;如果不存在,就直接创建虚拟网络设备edge0,至于虚拟网络设备edge0具体是什么,怎么创建的,目前官方还没有实现。
启动服务
进入server.Start()定义:
kubeedge/edgemesh/pkg/server/server.go
func Start() {// Initialize the resolvers r := &resolver.MyResolver{"http"} resolver.RegisterResolver(r) //Initialize the handlers config.GlobalDefinition = &model.GlobalCfg{} config.GlobalDefinition.Panel.Infra = "fake" opts := control.Options{ Infra: config.GlobalDefinition.Panel.Infra, Address: config.GlobalDefinition.Panel.Settings["address"], } config.GlobalDefinition.Ssl = make(map[string]string) control.Init(opts) opt := registry.Options{} registry.DefaultServiceDiscoveryService = edgeregistry.NewServiceDiscovery(opt) myStrategy := mconfig.CONFIG.GetConfigurationByKey("mesh.loadbalance.strategy-name").(string) loadbalancer.InstallStrategy(myStrategy, func() loadbalancer.Strategy { switch myStrategy { case "RoundRobin": return &loadbalancer.RoundRobinStrategy{} case "Random": return &loadbalancer.RandomStrategy{} default: return &loadbalancer.RoundRobinStrategy{} } }) //Start dns server go DnsStart() //Start server StartTCP() }
Start()函数做了3块事情:
1. 初始化resolvers、handlers
初始化的resolvers、handlers在TCP服务处理连接的过程中被使用。
2. 启动 DNS服务
go DnsStart()
该DNS服务主要为节点内的应用做域名解析。
3. 启动TCP服务
StartTCP()
该TCP服务在节点间做流量代理。
通过一个for循环接收通信管道中关于edgemesh的信息并处理
kubeedge/edgemesh/pkg/module.go
//Start sets context and starts the controller func (em *EdgeMesh) Start(c *context.Context) { ... // we need watch message to update the cache of instances for { if msg, ok := em.context.Receive(constant.ModuleNameEdgeMesh); ok == nil { proxy.MsgProcess(msg) klog.Infof("get message: %v", msg) continue } } }
进入proxy.MsgProcess(...)函数定义:
kubeedge/edgemesh/pkg/proxy/proxy.go
// MsgProcess process from metaManager and start a proxy server func MsgProcess(msg model.Message) { svcs := filterResourceType(msg) ... for _, svc := range svcs { svcName := svc.Namespace + "." + svc.Name if !IsL4Proxy(&svc) { // when server protocol update to http delServer(svcName) continue } port := make([]int32, 0) targetPort := make([]int32, 0) for _, p := range svc.Spec.Ports { // this version will support TCP only if p.Protocol == "TCP" { port = append(port, p.Port) // this version will not support string type targetPort = append(targetPort, p.TargetPort.IntVal) } } if len(port) == 0 || len(targetPort) == 0 { continue } switch msg.GetOperation() { case "insert": addServer(svcName, port) case "delete": delServer(svcName) case "update": updateServer(svcName, port) default: klog.Infof("[L4 proxy] Unknown operation") } st := addrByService.getAddrTable(svcName) if st != nil { st.targetPort = targetPort } } }
MsgProcess(...)函数处理的是metamanager模块发送过来的service信息,首先,根据service的命名规范、支持的协议对收到的service信息进行过滤;然后,根据信息操作类型(insert、delete、update)对信息进行具体操作,这些操作都是在节点的缓存中进行的;最后,对相应service的targetPort进行设置。
到此,edgecore的edgemesh模块的剖析就结束了。
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