dotcloud/docker

//go:generate pluginrpc-gen -i $GOFILE -o proxy.go -type volumeDriver -name VolumeDriver

package drivers // import "github.com/docker/docker/volume/drivers"

import (
    "context"
    "fmt"
    "sort"
    "sync"

    "github.com/containerd/log"
    "github.com/docker/docker/errdefs"
    getter "github.com/docker/docker/pkg/plugingetter"
    "github.com/docker/docker/pkg/plugins"
    "github.com/docker/docker/volume"
    "github.com/moby/locker"
    "github.com/pkg/errors"
)

const extName = "VolumeDriver"

// volumeDriver defines the available functions that volume plugins must implement.
// This interface is only defined to generate the proxy objects.
// It's not intended to be public or reused.
//
//nolint:unused
type volumeDriver interface {
    // Create a volume with the given name
    Create(name string, opts map[string]string) (err error)
    // Remove the volume with the given name
    Remove(name string) (err error)
    // Path returns the mountpoint of the given volume.
    Path(name string) (mountpoint string, err error)
    // Mount the given volume and return the mountpoint
    Mount(name, id string) (mountpoint string, err error)
    // Unmount the given volume
    Unmount(name, id string) (err error)
    // List lists all the volumes known to the driver
    List() (volumes []*proxyVolume, err error)
    // Get retrieves the volume with the requested name
    Get(name string) (volume *proxyVolume, err error)
    // Capabilities gets the list of capabilities of the driver
    Capabilities() (capabilities volume.Capability, err error)
}

// Store is an in-memory store for volume drivers
type Store struct {
    extensions   map[string]volume.Driver
    mu           sync.Mutex
    driverLock   *locker.Locker
    pluginGetter getter.PluginGetter
}

// NewStore creates a new volume driver store
func NewStore(pg getter.PluginGetter) *Store {
    return &Store{
        extensions:   make(map[string]volume.Driver),
        driverLock:   locker.New(),
        pluginGetter: pg,
    }
}

type driverNotFoundError string

func (e driverNotFoundError) Error() string {
    return "volume driver not found: " + string(e)
}

func (driverNotFoundError) NotFound() {}

// lookup returns the driver associated with the given name. If a
// driver with the given name has not been registered it checks if
// there is a VolumeDriver plugin available with the given name.
func (s *Store) lookup(name string, mode int) (volume.Driver, error) {
    if name == "" {
        return nil, errdefs.InvalidParameter(errors.New("driver name cannot be empty"))
    }
    s.driverLock.Lock(name)
    defer s.driverLock.Unlock(name)

    s.mu.Lock()
    ext, ok := s.extensions[name]
    s.mu.Unlock()
    if ok {
        return ext, nil
    }
    if s.pluginGetter != nil {
        p, err := s.pluginGetter.Get(name, extName, mode)
        if err != nil {
            return nil, errors.Wrap(err, "error looking up volume plugin "+name)
        }

        d, err := makePluginAdapter(p)
        if err != nil {
            return nil, errors.Wrap(err, "error making plugin client")
        }
        if err := validateDriver(d); err != nil {
            if mode > 0 {
                // Undo any reference count changes from the initial `Get`
                if _, err := s.pluginGetter.Get(name, extName, mode*-1); err != nil {
                    log.G(context.TODO()).WithError(err).WithField("action", "validate-driver").WithField("plugin", name).Error("error releasing reference to plugin")
                }
            }
            return nil, err
        }

        if p.IsV1() {
            s.mu.Lock()
            s.extensions[name] = d
            s.mu.Unlock()
        }
        return d, nil
    }
    return nil, driverNotFoundError(name)
}

func validateDriver(vd volume.Driver) error {
    scope := vd.Scope()
    if scope != volume.LocalScope && scope != volume.GlobalScope {
        return fmt.Errorf("Driver %q provided an invalid capability scope: %s", vd.Name(), scope)
    }
    return nil
}

// Register associates the given driver to the given name, checking if
// the name is already associated
func (s *Store) Register(d volume.Driver, name string) bool {
    if name == "" {
        return false
    }

    s.mu.Lock()
    defer s.mu.Unlock()

    if _, exists := s.extensions[name]; exists {
        return false
    }

    if err := validateDriver(d); err != nil {
        return false
    }

    s.extensions[name] = d
    return true
}

// GetDriver returns a volume driver by its name.
// If the driver is empty, it looks for the local driver.
func (s *Store) GetDriver(name string) (volume.Driver, error) {
    return s.lookup(name, getter.Lookup)
}

// CreateDriver returns a volume driver by its name and increments RefCount.
// If the driver is empty, it looks for the local driver.
func (s *Store) CreateDriver(name string) (volume.Driver, error) {
    return s.lookup(name, getter.Acquire)
}

// ReleaseDriver returns a volume driver by its name and decrements RefCount..
// If the driver is empty, it looks for the local driver.
func (s *Store) ReleaseDriver(name string) (volume.Driver, error) {
    return s.lookup(name, getter.Release)
}

// GetDriverList returns list of volume drivers registered.
// If no driver is registered, empty string list will be returned.
func (s *Store) GetDriverList() []string {
    var driverList []string
    s.mu.Lock()
    defer s.mu.Unlock()
    for driverName := range s.extensions {
        driverList = append(driverList, driverName)
    }
    sort.Strings(driverList)
    return driverList
}

// GetAllDrivers lists all the registered drivers
func (s *Store) GetAllDrivers() ([]volume.Driver, error) {
    var plugins []getter.CompatPlugin
    if s.pluginGetter != nil {
        var err error
        plugins, err = s.pluginGetter.GetAllByCap(extName)
        if err != nil {
            return nil, fmt.Errorf("error listing plugins: %v", err)
        }
    }
    var ds []volume.Driver

    s.mu.Lock()
    defer s.mu.Unlock()

    for _, d := range s.extensions {
        ds = append(ds, d)
    }

    for _, p := range plugins {
        name := p.Name()

        if _, ok := s.extensions[name]; ok {
            continue
        }

        ext, err := makePluginAdapter(p)
        if err != nil {
            return nil, errors.Wrap(err, "error making plugin client")
        }
        if p.IsV1() {
            s.extensions[name] = ext
        }
        ds = append(ds, ext)
    }
    return ds, nil
}

func makePluginAdapter(p getter.CompatPlugin) (*volumeDriverAdapter, error) {
    if pc, ok := p.(getter.PluginWithV1Client); ok {
        return &volumeDriverAdapter{name: p.Name(), scopePath: p.ScopedPath, proxy: &volumeDriverProxy{pc.Client()}}, nil
    }

    pa, ok := p.(getter.PluginAddr)
    if !ok {
        return nil, errdefs.System(errors.Errorf("got unknown plugin instance %T", p))
    }

    if pa.Protocol() != plugins.ProtocolSchemeHTTPV1 {
        return nil, errors.Errorf("plugin protocol not supported: %s", p)
    }

    addr := pa.Addr()
    client, err := plugins.NewClientWithTimeout(addr.Network()+"://"+addr.String(), nil, pa.Timeout())
    if err != nil {
        return nil, errors.Wrap(err, "error creating plugin client")
    }

    return &volumeDriverAdapter{name: p.Name(), scopePath: p.ScopedPath, proxy: &volumeDriverProxy{client}}, nil
}