Swarmkit notes (7)--exec. Executor interface

This is a creation in Article, where the information may have evolved or changed.

exec.Executor interfaceDefinition (located agent/exec/executor.go ):

// Executor provides controllers for tasks.type Executor interface {    // Describe returns the underlying node description.    Describe(ctx context.Context) (*api.NodeDescription, error)    // Configure uses the node object state to propagate node    // state to the underlying executor.    Configure(ctx context.Context, node *api.Node) error    // Controller provides a controller for the given task.    Controller(t *api.Task) (Controller, error)    // SetNetworkBootstrapKeys passes the symmetric keys from the    // manager to the executor.    SetNetworkBootstrapKeys([]*api.EncryptionKey) error}

container PackageImplements the executor structure (located agent/exec/container/executor.go ):

import engineapi "github.com/docker/engine-api/client"type executor struct {    client engineapi.APIClient}

There is only one member: one Docker APIClient . executorthe structure actually implements only the following two methods:

Describe returns the underlying node description from the Docker Client.func (e *executor) Describe (CTX context. Context) (*api. Nodedescription, error) {info, err: = E.client.info (CTX) if err! = Nil {return nil, err} plugins: = Map[api.            plugindescription]struct{}{} addplugins: = Func (Typ string, names []string) {for _, Name: = range Names { Plugins[api. plugindescription{Type:typ, Name:name,}] = struct{}{}}} Addplu Gins ("Volume", info. Plugins.volume)//ADD Builtin Driver "overlay" (the only builtin multi-host driver) to//The plugin list by defaul    T. addplugins ("Network", append ([]string{"Overlay"}, info.Plugins.Network ...)) Addplugins ("Authorization", info. plugins.authorization) Pluginfields: = Make ([]api. Plugindescription, 0, Len (plugins)) for k: = Range Plugins {pluginfields = append (Pluginfields, k)} sort . Sort (Sortedplugins (Pluginfields))//PARSE []string labels to a map[string]string labels: = map[string]string{} for _, L: = range info. Labels {stringslice: = strings. SPLITN (l, "=", 2)//This is the last value of the list for a given key//Ideally, one shouldn ' t         IGN multiple values to the same key if Len (Stringslice) > 1 {labels[stringslice[0]] = stringslice[1] }} Description: = &api. nodedescription{Hostname:info. Name, Platform: &api. platform{Architecture:info. Architecture, Os:info. OSType,}, Engine: &api. enginedescription{Engineversion:info. ServerVersion, Labels:labels, Plugins:pluginfields,}, Resources: & Api. resources{Nanocpus:int64 (info. NCPU) * 1e9, Memorybytes:info. Memtotal,},} return description, nil}//Controller returns a Docker container Controller.func (e *executor) Controller (t *api. Task) (exec. Controller, error) {CTLR, err: = Newcontroller (e.client, T) if err! = Nil {return nil, err} return C TLR, nil}

Describe()method returns the current Docker engine resource configuration information, and Controller() then returns a container.controller struct.

Where client the initialization of the is located:

        client, err := engineapi.NewClient(engineAddr, "", nil, nil)        if err != nil {            return err        }        executor := container.NewExecutor(client)

If no engineAddr special settings are made, their default values are used: unix:///var/run/docker.sock . The client value defaults to the following:

(dlv) p client*github.com/docker/swarmkit/vendor/github.com/docker/engine-api/client.Client {        proto: "unix",        addr: "/var/run/docker.sock",        basePath: "",        transport: (unreadable interface type "*transport.apiTransport" not found for 0xc8202ecbd8: no type entry found, use 'types' for a list of valid types),        version: "",        customHTTPHeaders: map[string]string [],}