149 lines
3.6 KiB
Go
149 lines
3.6 KiB
Go
// Package plugins provides structures and helper functions to manage Docker
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// plugins.
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//
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// Docker discovers plugins by looking for them in the plugin directory whenever
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// a user or container tries to use one by name. UNIX domain socket files must
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// be located under /run/docker/plugins, whereas spec files can be located
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// either under /etc/docker/plugins or /usr/lib/docker/plugins. This is handled
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// by the Registry interface, which lets you list all plugins or get a plugin by
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// its name if it exists.
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//
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// The plugins need to implement an HTTP server and bind this to the UNIX socket
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// or the address specified in the spec files.
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// A handshake is send at /Plugin.Activate, and plugins are expected to return
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// a Manifest with a list of of Docker subsystems which this plugin implements.
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//
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// In order to use a plugins, you can use the ``Get`` with the name of the
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// plugin and the subsystem it implements.
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//
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// plugin, err := plugins.Get("example", "VolumeDriver")
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// if err != nil {
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// return fmt.Errorf("Error looking up volume plugin example: %v", err)
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// }
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package plugins
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import (
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"errors"
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"sync"
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"github.com/Sirupsen/logrus"
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"github.com/docker/docker/pkg/tlsconfig"
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)
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var (
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// ErrNotImplements is returned if the plugin does not implement the requested driver.
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ErrNotImplements = errors.New("Plugin does not implement the requested driver")
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)
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type plugins struct {
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sync.Mutex
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plugins map[string]*Plugin
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}
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var (
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storage = plugins{plugins: make(map[string]*Plugin)}
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extpointHandlers = make(map[string]func(string, *Client))
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)
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// Manifest lists what a plugin implements.
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type Manifest struct {
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// List of subsystem the plugin implements.
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Implements []string
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}
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// Plugin is the definition of a docker plugin.
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type Plugin struct {
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// Name of the plugin
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Name string `json:"-"`
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// Address of the plugin
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Addr string
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// TLS configuration of the plugin
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TLSConfig tlsconfig.Options
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// Client attached to the plugin
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Client *Client `json:"-"`
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// Manifest of the plugin (see above)
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Manifest *Manifest `json:"-"`
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}
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func newLocalPlugin(name, addr string) *Plugin {
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return &Plugin{
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Name: name,
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Addr: addr,
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TLSConfig: tlsconfig.Options{InsecureSkipVerify: true},
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}
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}
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func (p *Plugin) activate() error {
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c, err := NewClient(p.Addr, p.TLSConfig)
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if err != nil {
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return err
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}
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p.Client = c
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m := new(Manifest)
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if err = p.Client.Call("Plugin.Activate", nil, m); err != nil {
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return err
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}
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logrus.Debugf("%s's manifest: %v", p.Name, m)
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p.Manifest = m
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for _, iface := range m.Implements {
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handler, handled := extpointHandlers[iface]
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if !handled {
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continue
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}
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handler(p.Name, p.Client)
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}
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return nil
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}
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func load(name string) (*Plugin, error) {
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registry := newLocalRegistry()
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pl, err := registry.Plugin(name)
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if err != nil {
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return nil, err
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}
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if err := pl.activate(); err != nil {
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return nil, err
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}
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return pl, nil
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}
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func get(name string) (*Plugin, error) {
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storage.Lock()
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defer storage.Unlock()
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pl, ok := storage.plugins[name]
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if ok {
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return pl, nil
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}
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pl, err := load(name)
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if err != nil {
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return nil, err
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}
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logrus.Debugf("Plugin: %v", pl)
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storage.plugins[name] = pl
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return pl, nil
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}
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// Get returns the plugin given the specified name and requested implementation.
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func Get(name, imp string) (*Plugin, error) {
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pl, err := get(name)
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if err != nil {
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return nil, err
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}
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for _, driver := range pl.Manifest.Implements {
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logrus.Debugf("%s implements: %s", name, driver)
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if driver == imp {
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return pl, nil
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}
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}
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return nil, ErrNotImplements
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}
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// Handle adds the specified function to the extpointHandlers.
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func Handle(iface string, fn func(string, *Client)) {
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extpointHandlers[iface] = fn
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}
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