package store // import "github.com/docker/docker/volume/store" import ( "net" "os" "path/filepath" "runtime" "sync" "time" "github.com/pkg/errors" "github.com/boltdb/bolt" "github.com/docker/docker/pkg/locker" "github.com/docker/docker/volume" "github.com/docker/docker/volume/drivers" "github.com/sirupsen/logrus" ) const ( volumeDataDir = "volumes" ) type volumeWrapper struct { volume.Volume labels map[string]string scope string options map[string]string } func (v volumeWrapper) Options() map[string]string { options := map[string]string{} for key, value := range v.options { options[key] = value } return options } func (v volumeWrapper) Labels() map[string]string { return v.labels } func (v volumeWrapper) Scope() string { return v.scope } func (v volumeWrapper) CachedPath() string { if vv, ok := v.Volume.(interface { CachedPath() string }); ok { return vv.CachedPath() } return v.Volume.Path() } // New initializes a VolumeStore to keep // reference counting of volumes in the system. func New(rootPath string) (*VolumeStore, error) { vs := &VolumeStore{ locks: &locker.Locker{}, names: make(map[string]volume.Volume), refs: make(map[string]map[string]struct{}), labels: make(map[string]map[string]string), options: make(map[string]map[string]string), } if rootPath != "" { // initialize metadata store volPath := filepath.Join(rootPath, volumeDataDir) if err := os.MkdirAll(volPath, 750); err != nil { return nil, err } dbPath := filepath.Join(volPath, "metadata.db") var err error vs.db, err = bolt.Open(dbPath, 0600, &bolt.Options{Timeout: 1 * time.Second}) if err != nil { return nil, errors.Wrap(err, "error while opening volume store metadata database") } // initialize volumes bucket if err := vs.db.Update(func(tx *bolt.Tx) error { if _, err := tx.CreateBucketIfNotExists(volumeBucketName); err != nil { return errors.Wrap(err, "error while setting up volume store metadata database") } return nil }); err != nil { return nil, err } } vs.restore() return vs, nil } func (s *VolumeStore) getNamed(name string) (volume.Volume, bool) { s.globalLock.RLock() v, exists := s.names[name] s.globalLock.RUnlock() return v, exists } func (s *VolumeStore) setNamed(v volume.Volume, ref string) { name := v.Name() s.globalLock.Lock() s.names[name] = v if len(ref) > 0 { if s.refs[name] == nil { s.refs[name] = make(map[string]struct{}) } s.refs[name][ref] = struct{}{} } s.globalLock.Unlock() } // hasRef returns true if the given name has at least one ref. // Callers of this function are expected to hold the name lock. func (s *VolumeStore) hasRef(name string) bool { s.globalLock.RLock() l := len(s.refs[name]) s.globalLock.RUnlock() return l > 0 } // getRefs gets the list of refs for a given name // Callers of this function are expected to hold the name lock. func (s *VolumeStore) getRefs(name string) []string { s.globalLock.RLock() defer s.globalLock.RUnlock() refs := make([]string, 0, len(s.refs[name])) for r := range s.refs[name] { refs = append(refs, r) } return refs } // Purge allows the cleanup of internal data on docker in case // the internal data is out of sync with volumes driver plugins. func (s *VolumeStore) Purge(name string) { s.globalLock.Lock() v, exists := s.names[name] if exists { driverName := v.DriverName() if _, err := volumedrivers.ReleaseDriver(driverName); err != nil { logrus.WithError(err).WithField("driver", driverName).Error("Error releasing reference to volume driver") } } if err := s.removeMeta(name); err != nil { logrus.Errorf("Error removing volume metadata for volume %q: %v", name, err) } delete(s.names, name) delete(s.refs, name) delete(s.labels, name) delete(s.options, name) s.globalLock.Unlock() } // VolumeStore is a struct that stores the list of volumes available and keeps track of their usage counts type VolumeStore struct { // locks ensures that only one action is being performed on a particular volume at a time without locking the entire store // since actions on volumes can be quite slow, this ensures the store is free to handle requests for other volumes. locks *locker.Locker // globalLock is used to protect access to mutable structures used by the store object globalLock sync.RWMutex // names stores the volume name -> volume relationship. // This is used for making lookups faster so we don't have to probe all drivers names map[string]volume.Volume // refs stores the volume name and the list of things referencing it refs map[string]map[string]struct{} // labels stores volume labels for each volume labels map[string]map[string]string // options stores volume options for each volume options map[string]map[string]string db *bolt.DB } // List proxies to all registered volume drivers to get the full list of volumes // If a driver returns a volume that has name which conflicts with another volume from a different driver, // the first volume is chosen and the conflicting volume is dropped. func (s *VolumeStore) List() ([]volume.Volume, []string, error) { vols, warnings, err := s.list() if err != nil { return nil, nil, &OpErr{Err: err, Op: "list"} } var out []volume.Volume for _, v := range vols { name := normalizeVolumeName(v.Name()) s.locks.Lock(name) storedV, exists := s.getNamed(name) // Note: it's not safe to populate the cache here because the volume may have been // deleted before we acquire a lock on its name if exists && storedV.DriverName() != v.DriverName() { logrus.Warnf("Volume name %s already exists for driver %s, not including volume returned by %s", v.Name(), storedV.DriverName(), v.DriverName()) s.locks.Unlock(v.Name()) continue } out = append(out, v) s.locks.Unlock(v.Name()) } return out, warnings, nil } // list goes through each volume driver and asks for its list of volumes. func (s *VolumeStore) list() ([]volume.Volume, []string, error) { var ( ls []volume.Volume warnings []string ) drivers, err := volumedrivers.GetAllDrivers() if err != nil { return nil, nil, err } type vols struct { vols []volume.Volume err error driverName string } chVols := make(chan vols, len(drivers)) for _, vd := range drivers { go func(d volume.Driver) { vs, err := d.List() if err != nil { chVols <- vols{driverName: d.Name(), err: &OpErr{Err: err, Name: d.Name(), Op: "list"}} return } for i, v := range vs { s.globalLock.RLock() vs[i] = volumeWrapper{v, s.labels[v.Name()], d.Scope(), s.options[v.Name()]} s.globalLock.RUnlock() } chVols <- vols{vols: vs} }(vd) } badDrivers := make(map[string]struct{}) for i := 0; i < len(drivers); i++ { vs := <-chVols if vs.err != nil { warnings = append(warnings, vs.err.Error()) badDrivers[vs.driverName] = struct{}{} logrus.Warn(vs.err) } ls = append(ls, vs.vols...) } if len(badDrivers) > 0 { s.globalLock.RLock() for _, v := range s.names { if _, exists := badDrivers[v.DriverName()]; exists { ls = append(ls, v) } } s.globalLock.RUnlock() } return ls, warnings, nil } // CreateWithRef creates a volume with the given name and driver and stores the ref // This ensures there's no race between creating a volume and then storing a reference. func (s *VolumeStore) CreateWithRef(name, driverName, ref string, opts, labels map[string]string) (volume.Volume, error) { name = normalizeVolumeName(name) s.locks.Lock(name) defer s.locks.Unlock(name) v, err := s.create(name, driverName, opts, labels) if err != nil { if _, ok := err.(*OpErr); ok { return nil, err } return nil, &OpErr{Err: err, Name: name, Op: "create"} } s.setNamed(v, ref) return v, nil } // Create creates a volume with the given name and driver. // This is just like CreateWithRef() except we don't store a reference while holding the lock. func (s *VolumeStore) Create(name, driverName string, opts, labels map[string]string) (volume.Volume, error) { return s.CreateWithRef(name, driverName, "", opts, labels) } // checkConflict checks the local cache for name collisions with the passed in name, // for existing volumes with the same name but in a different driver. // This is used by `Create` as a best effort to prevent name collisions for volumes. // If a matching volume is found that is not a conflict that is returned so the caller // does not need to perform an additional lookup. // When no matching volume is found, both returns will be nil // // Note: This does not probe all the drivers for name collisions because v1 plugins // are very slow, particularly if the plugin is down, and cause other issues, // particularly around locking the store. // TODO(cpuguy83): With v2 plugins this shouldn't be a problem. Could also potentially // use a connect timeout for this kind of check to ensure we aren't blocking for a // long time. func (s *VolumeStore) checkConflict(name, driverName string) (volume.Volume, error) { // check the local cache v, _ := s.getNamed(name) if v == nil { return nil, nil } vDriverName := v.DriverName() var conflict bool if driverName != "" { // Retrieve canonical driver name to avoid inconsistencies (for example // "plugin" vs. "plugin:latest") vd, err := volumedrivers.GetDriver(driverName) if err != nil { return nil, err } if vDriverName != vd.Name() { conflict = true } } // let's check if the found volume ref // is stale by checking with the driver if it still exists exists, err := volumeExists(v) if err != nil { return nil, errors.Wrapf(errNameConflict, "found reference to volume '%s' in driver '%s', but got an error while checking the driver: %v", name, vDriverName, err) } if exists { if conflict { return nil, errors.Wrapf(errNameConflict, "driver '%s' already has volume '%s'", vDriverName, name) } return v, nil } if s.hasRef(v.Name()) { // Containers are referencing this volume but it doesn't seem to exist anywhere. // Return a conflict error here, the user can fix this with `docker volume rm -f` return nil, errors.Wrapf(errNameConflict, "found references to volume '%s' in driver '%s' but the volume was not found in the driver -- you may need to remove containers referencing this volume or force remove the volume to re-create it", name, vDriverName) } // doesn't exist, so purge it from the cache s.Purge(name) return nil, nil } // volumeExists returns if the volume is still present in the driver. // An error is returned if there was an issue communicating with the driver. func volumeExists(v volume.Volume) (bool, error) { exists, err := lookupVolume(v.DriverName(), v.Name()) if err != nil { return false, err } return exists != nil, nil } // create asks the given driver to create a volume with the name/opts. // If a volume with the name is already known, it will ask the stored driver for the volume. // If the passed in driver name does not match the driver name which is stored // for the given volume name, an error is returned after checking if the reference is stale. // If the reference is stale, it will be purged and this create can continue. // It is expected that callers of this function hold any necessary locks. func (s *VolumeStore) create(name, driverName string, opts, labels map[string]string) (volume.Volume, error) { // Validate the name in a platform-specific manner // volume name validation is specific to the host os and not on container image // windows/lcow should have an equivalent volumename validation logic so we create a parser for current host OS parser := volume.NewParser(runtime.GOOS) err := parser.ValidateVolumeName(name) if err != nil { return nil, err } v, err := s.checkConflict(name, driverName) if err != nil { return nil, err } if v != nil { // there is an existing volume, if we already have this stored locally, return it. // TODO: there could be some inconsistent details such as labels here if vv, _ := s.getNamed(v.Name()); vv != nil { return vv, nil } } // Since there isn't a specified driver name, let's see if any of the existing drivers have this volume name if driverName == "" { v, _ = s.getVolume(name) if v != nil { return v, nil } } vd, err := volumedrivers.CreateDriver(driverName) if err != nil { return nil, &OpErr{Op: "create", Name: name, Err: err} } logrus.Debugf("Registering new volume reference: driver %q, name %q", vd.Name(), name) if v, _ = vd.Get(name); v == nil { v, err = vd.Create(name, opts) if err != nil { if _, err := volumedrivers.ReleaseDriver(driverName); err != nil { logrus.WithError(err).WithField("driver", driverName).Error("Error releasing reference to volume driver") } return nil, err } } s.globalLock.Lock() s.labels[name] = labels s.options[name] = opts s.refs[name] = make(map[string]struct{}) s.globalLock.Unlock() metadata := volumeMetadata{ Name: name, Driver: vd.Name(), Labels: labels, Options: opts, } if err := s.setMeta(name, metadata); err != nil { return nil, err } return volumeWrapper{v, labels, vd.Scope(), opts}, nil } // GetWithRef gets a volume with the given name from the passed in driver and stores the ref // This is just like Get(), but we store the reference while holding the lock. // This makes sure there are no races between checking for the existence of a volume and adding a reference for it func (s *VolumeStore) GetWithRef(name, driverName, ref string) (volume.Volume, error) { name = normalizeVolumeName(name) s.locks.Lock(name) defer s.locks.Unlock(name) vd, err := volumedrivers.GetDriver(driverName) if err != nil { return nil, &OpErr{Err: err, Name: name, Op: "get"} } v, err := vd.Get(name) if err != nil { return nil, &OpErr{Err: err, Name: name, Op: "get"} } s.setNamed(v, ref) s.globalLock.RLock() defer s.globalLock.RUnlock() return volumeWrapper{v, s.labels[name], vd.Scope(), s.options[name]}, nil } // Get looks if a volume with the given name exists and returns it if so func (s *VolumeStore) Get(name string) (volume.Volume, error) { name = normalizeVolumeName(name) s.locks.Lock(name) defer s.locks.Unlock(name) v, err := s.getVolume(name) if err != nil { return nil, &OpErr{Err: err, Name: name, Op: "get"} } s.setNamed(v, "") return v, nil } // getVolume requests the volume, if the driver info is stored it just accesses that driver, // if the driver is unknown it probes all drivers until it finds the first volume with that name. // it is expected that callers of this function hold any necessary locks func (s *VolumeStore) getVolume(name string) (volume.Volume, error) { var meta volumeMetadata meta, err := s.getMeta(name) if err != nil { return nil, err } driverName := meta.Driver if driverName == "" { s.globalLock.RLock() v, exists := s.names[name] s.globalLock.RUnlock() if exists { meta.Driver = v.DriverName() if err := s.setMeta(name, meta); err != nil { return nil, err } } } if meta.Driver != "" { vol, err := lookupVolume(meta.Driver, name) if err != nil { return nil, err } if vol == nil { s.Purge(name) return nil, errNoSuchVolume } var scope string vd, err := volumedrivers.GetDriver(meta.Driver) if err == nil { scope = vd.Scope() } return volumeWrapper{vol, meta.Labels, scope, meta.Options}, nil } logrus.Debugf("Probing all drivers for volume with name: %s", name) drivers, err := volumedrivers.GetAllDrivers() if err != nil { return nil, err } for _, d := range drivers { v, err := d.Get(name) if err != nil || v == nil { continue } meta.Driver = v.DriverName() if err := s.setMeta(name, meta); err != nil { return nil, err } return volumeWrapper{v, meta.Labels, d.Scope(), meta.Options}, nil } return nil, errNoSuchVolume } // lookupVolume gets the specified volume from the specified driver. // This will only return errors related to communications with the driver. // If the driver returns an error that is not communication related the // error is logged but not returned. // If the volume is not found it will return `nil, nil`` func lookupVolume(driverName, volumeName string) (volume.Volume, error) { vd, err := volumedrivers.GetDriver(driverName) if err != nil { return nil, errors.Wrapf(err, "error while checking if volume %q exists in driver %q", volumeName, driverName) } v, err := vd.Get(volumeName) if err != nil { err = errors.Cause(err) if _, ok := err.(net.Error); ok { if v != nil { volumeName = v.Name() driverName = v.DriverName() } return nil, errors.Wrapf(err, "error while checking if volume %q exists in driver %q", volumeName, driverName) } // At this point, the error could be anything from the driver, such as "no such volume" // Let's not check an error here, and instead check if the driver returned a volume logrus.WithError(err).WithField("driver", driverName).WithField("volume", volumeName).Warnf("Error while looking up volume") } return v, nil } // Remove removes the requested volume. A volume is not removed if it has any refs func (s *VolumeStore) Remove(v volume.Volume) error { name := normalizeVolumeName(v.Name()) s.locks.Lock(name) defer s.locks.Unlock(name) if s.hasRef(name) { return &OpErr{Err: errVolumeInUse, Name: v.Name(), Op: "remove", Refs: s.getRefs(name)} } vd, err := volumedrivers.GetDriver(v.DriverName()) if err != nil { return &OpErr{Err: err, Name: v.DriverName(), Op: "remove"} } logrus.Debugf("Removing volume reference: driver %s, name %s", v.DriverName(), name) vol := unwrapVolume(v) if err := vd.Remove(vol); err != nil { return &OpErr{Err: err, Name: name, Op: "remove"} } s.Purge(name) return nil } // Dereference removes the specified reference to the volume func (s *VolumeStore) Dereference(v volume.Volume, ref string) { name := v.Name() s.locks.Lock(name) defer s.locks.Unlock(name) s.globalLock.Lock() defer s.globalLock.Unlock() if s.refs[name] != nil { delete(s.refs[name], ref) } } // Refs gets the current list of refs for the given volume func (s *VolumeStore) Refs(v volume.Volume) []string { name := v.Name() s.locks.Lock(name) defer s.locks.Unlock(name) return s.getRefs(name) } // FilterByDriver returns the available volumes filtered by driver name func (s *VolumeStore) FilterByDriver(name string) ([]volume.Volume, error) { vd, err := volumedrivers.GetDriver(name) if err != nil { return nil, &OpErr{Err: err, Name: name, Op: "list"} } ls, err := vd.List() if err != nil { return nil, &OpErr{Err: err, Name: name, Op: "list"} } for i, v := range ls { options := map[string]string{} s.globalLock.RLock() for key, value := range s.options[v.Name()] { options[key] = value } ls[i] = volumeWrapper{v, s.labels[v.Name()], vd.Scope(), options} s.globalLock.RUnlock() } return ls, nil } // FilterByUsed returns the available volumes filtered by if they are in use or not. // `used=true` returns only volumes that are being used, while `used=false` returns // only volumes that are not being used. func (s *VolumeStore) FilterByUsed(vols []volume.Volume, used bool) []volume.Volume { return s.filter(vols, func(v volume.Volume) bool { s.locks.Lock(v.Name()) hasRef := s.hasRef(v.Name()) s.locks.Unlock(v.Name()) return used == hasRef }) } // filterFunc defines a function to allow filter volumes in the store type filterFunc func(vol volume.Volume) bool // filter returns the available volumes filtered by a filterFunc function func (s *VolumeStore) filter(vols []volume.Volume, f filterFunc) []volume.Volume { var ls []volume.Volume for _, v := range vols { if f(v) { ls = append(ls, v) } } return ls } func unwrapVolume(v volume.Volume) volume.Volume { if vol, ok := v.(volumeWrapper); ok { return vol.Volume } return v } // Shutdown releases all resources used by the volume store // It does not make any changes to volumes, drivers, etc. func (s *VolumeStore) Shutdown() error { return s.db.Close() }