docker筆記（14）——docker swarm功能程式碼分析（1）

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 1.12整合了docker swarm功能，其client的相關代碼位於api/client/swarm檔案夾下。以docker swarm init命令的代碼（api/client/swarm/init.go）為例：

const (    generatedSecretEntropyBytes = 16    generatedSecretBase         = 36    // floor(log(2^128-1, 36)) + 1    maxGeneratedSecretLength = 25)type initOptions struct {    swarmOptions    listenAddr NodeAddrOption    // Not a NodeAddrOption because it has no default port.    advertiseAddr   string    forceNewCluster bool}func newInitCommand(dockerCli *client.DockerCli) *cobra.Command {    opts := initOptions{        listenAddr: NewListenAddrOption(),    }    cmd := &cobra.Command{        Use:   "init [OPTIONS]",        Short: "Initialize a swarm",        Args:  cli.NoArgs,        RunE: func(cmd *cobra.Command, args []string) error {            return runInit(dockerCli, cmd.Flags(), opts)        },    }    flags := cmd.Flags()    flags.Var(&opts.listenAddr, flagListenAddr, "Listen address (format: <ip|interface>[:port])")    flags.StringVar(&opts.advertiseAddr, flagAdvertiseAddr, "", "Advertised address (format: <ip|interface>[:port])")    flags.BoolVar(&opts.forceNewCluster, "force-new-cluster", false, "Force create a new cluster from current state.")    addSwarmFlags(flags, &opts.swarmOptions)    return cmd}func runInit(dockerCli *client.DockerCli, flags *pflag.FlagSet, opts initOptions) error {    client := dockerCli.Client()    ctx := context.Background()    req := swarm.InitRequest{        ListenAddr:      opts.listenAddr.String(),        AdvertiseAddr:   opts.advertiseAddr,        ForceNewCluster: opts.forceNewCluster,        Spec:            opts.swarmOptions.ToSpec(),    }    nodeID, err := client.SwarmInit(ctx, req)    if err != nil {        if strings.Contains(err.Error(), "could not choose an IP address to advertise") || strings.Contains(err.Error(), "could not find the system's IP address") {            return errors.New(err.Error() + " - specify one with --advertise-addr")        }        return err    }    fmt.Fprintf(dockerCli.Out(), "Swarm initialized: current node (%s) is now a manager.\n\n", nodeID)    if err := printJoinCommand(ctx, dockerCli, nodeID, true, false); err != nil {        return err    }    fmt.Fprint(dockerCli.Out(), "To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.\n\n")    return nil}

其中client.DockerCli代表docker command line client：

// DockerCli represents the docker command line client.// Instances of the client can be returned from NewDockerCli.type DockerCli struct {    // initializing closure    init func() error    // configFile has the client configuration file    configFile *configfile.ConfigFile    // in holds the input stream and closer (io.ReadCloser) for the client.    in io.ReadCloser    // out holds the output stream (io.Writer) for the client.    out io.Writer    // err holds the error stream (io.Writer) for the client.    err io.Writer    // keyFile holds the key file as a string.    keyFile string    // inFd holds the file descriptor of the client's STDIN (if valid).    inFd uintptr    // outFd holds file descriptor of the client's STDOUT (if valid).    outFd uintptr    // isTerminalIn indicates whether the client's STDIN is a TTY    isTerminalIn bool    // isTerminalOut indicates whether the client's STDOUT is a TTY    isTerminalOut bool    // client is the http client that performs all API operations    client client.APIClient    // state holds the terminal input state    inState *term.State    // outState holds the terminal output state    outState *term.State}

其中的client成員便是engine-api/client，所以上述client.SwarmInit的代碼位於engine-api/client/swarm_init.go：

// SwarmInit initializes the Swarm.func (cli *Client) SwarmInit(ctx context.Context, req swarm.InitRequest) (string, error) {    serverResp, err := cli.post(ctx, "/swarm/init", nil, req, nil)    if err != nil {        return "", err    }    var response string    err = json.NewDecoder(serverResp.body).Decode(&response)    ensureReaderClosed(serverResp)    return response, err}