docker筆記（15）——docker swarm功能程式碼分析（2）

這是一個建立於 的文章，其中的資訊可能已經有所發展或是發生改變。

Docker daemon初始化響應docker client swarm相關命令的處理函數位於api/server/router/swarm/cluster.go：

// buildRouter is a router to talk with the build controllertype swarmRouter struct {    backend Backend    routes  []router.Route}// NewRouter initializes a new build routerfunc NewRouter(b Backend) router.Router {    r := &swarmRouter{        backend: b,    }    r.initRoutes()    return r}// Routes returns the available routers to the swarm controllerfunc (sr *swarmRouter) Routes() []router.Route {    return sr.routes}func (sr *swarmRouter) initRoutes() {    sr.routes = []router.Route{        router.NewPostRoute("/swarm/init", sr.initCluster),        router.NewPostRoute("/swarm/join", sr.joinCluster),        router.NewPostRoute("/swarm/leave", sr.leaveCluster),        router.NewGetRoute("/swarm", sr.inspectCluster),        router.NewPostRoute("/swarm/update", sr.updateCluster),        router.NewGetRoute("/services", sr.getServices),        router.NewGetRoute("/services/{id:.*}", sr.getService),        router.NewPostRoute("/services/create", sr.createService),        router.NewPostRoute("/services/{id:.*}/update", sr.updateService),        router.NewDeleteRoute("/services/{id:.*}", sr.removeService),        router.NewGetRoute("/nodes", sr.getNodes),        router.NewGetRoute("/nodes/{id:.*}", sr.getNode),        router.NewDeleteRoute("/nodes/{id:.*}", sr.removeNode),        router.NewPostRoute("/nodes/{id:.*}/update", sr.updateNode),        router.NewGetRoute("/tasks", sr.getTasks),        router.NewGetRoute("/tasks/{id:.*}", sr.getTask),    }}

以處理“/swarm/init”請求為例，實際的處理函數位於daemon/cluster/cluster.go：

// Init initializes new cluster from user provided request.func (c *Cluster) Init(req types.InitRequest) (string, error) {    c.Lock()    if node := c.node; node != nil {        if !req.ForceNewCluster {            c.Unlock()            return "", ErrSwarmExists        }        if err := c.stopNode(); err != nil {            c.Unlock()            return "", err        }    }    if err := validateAndSanitizeInitRequest(&req); err != nil {        c.Unlock()        return "", err    }    listenHost, listenPort, err := resolveListenAddr(req.ListenAddr)    if err != nil {        c.Unlock()        return "", err    }    advertiseHost, advertisePort, err := c.resolveAdvertiseAddr(req.AdvertiseAddr, listenPort)    if err != nil {        c.Unlock()        return "", err    }    localAddr := listenHost    // If the advertise address is not one of the system's    // addresses, we also require a listen address.    listenAddrIP := net.ParseIP(listenHost)    if listenAddrIP != nil && listenAddrIP.IsUnspecified() {        advertiseIP := net.ParseIP(advertiseHost)        if advertiseIP == nil {            // not an IP            c.Unlock()            return "", errMustSpecifyListenAddr        }        systemIPs := listSystemIPs()        found := false        for _, systemIP := range systemIPs {            if systemIP.Equal(advertiseIP) {                found = true                break            }        }        if !found {            c.Unlock()            return "", errMustSpecifyListenAddr        }        localAddr = advertiseIP.String()    }    // todo: check current state existing    n, err := c.startNewNode(req.ForceNewCluster, localAddr, "", net.JoinHostPort(listenHost, listenPort), net.JoinHostPort(advertiseHost, advertisePort), "", "")    if err != nil {        c.Unlock()        return "", err    }    c.Unlock()    select {    case <-n.Ready():        if err := initClusterSpec(n, req.Spec); err != nil {            return "", err        }        go c.reconnectOnFailure(n)        return n.NodeID(), nil    case <-n.done:        c.RLock()        defer c.RUnlock()        if !req.ForceNewCluster { // if failure on first attempt don't keep state            if err := c.clearState(); err != nil {                return "", err            }        }        return "", c.err    }}

它的核心是c.startNewNode函數，其主要邏輯如下：

......n, err := swarmagent.NewNode(&swarmagent.NodeConfig{    Hostname:           c.config.Name,    ForceNewCluster:    forceNewCluster,    ListenControlAPI:   filepath.Join(c.root, controlSocket),    ListenRemoteAPI:    listenAddr,    AdvertiseRemoteAPI: advertiseAddr,    JoinAddr:           joinAddr,    StateDir:           c.root,    JoinToken:          joinToken,    Executor:           container.NewExecutor(c.config.Backend),    HeartbeatTick:      1,    ElectionTick:       3,})if err != nil {    return nil, err}ctx := context.Background()if err := n.Start(ctx); err != nil {    return nil, err}......

即調用swarmkit的NewNode建立一個node，接下來便start這個節點。這個node是manager角色。