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driver.go
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driver.go
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package docker
import (
"context"
"encoding/json"
"fmt"
"math/rand"
"os"
"path/filepath"
"reflect"
"sort"
"sync"
"time"
"github.com/artpar/rclone/cmd/mountlib"
"github.com/artpar/rclone/fs"
"github.com/artpar/rclone/fs/config"
"github.com/artpar/rclone/lib/atexit"
"github.com/artpar/rclone/lib/file"
"github.com/artpar/rclone/vfs/vfscommon"
"github.com/artpar/rclone/vfs/vfsflags"
"github.com/coreos/go-systemd/v22/daemon"
)
// Driver implements docker driver api
type Driver struct {
root string
volumes map[string]*Volume
statePath string
dummy bool // disables real mounting
mntOpt mountlib.Options
vfsOpt vfscommon.Options
mu sync.Mutex
exitOnce sync.Once
hupChan chan os.Signal
monChan chan bool // exit if true for exit, refresh if false
}
// NewDriver makes a new docker driver
func NewDriver(ctx context.Context, root string, mntOpt *mountlib.Options, vfsOpt *vfscommon.Options, dummy, forgetState bool) (*Driver, error) {
// setup directories
cacheDir := config.GetCacheDir()
err := file.MkdirAll(cacheDir, 0700)
if err != nil {
return nil, fmt.Errorf("failed to create cache directory: %s: %w", cacheDir, err)
}
//err = file.MkdirAll(root, 0755)
if err != nil {
return nil, fmt.Errorf("failed to create mount root: %s: %w", root, err)
}
// setup driver state
if mntOpt == nil {
mntOpt = &mountlib.Opt
}
if vfsOpt == nil {
vfsOpt = &vfsflags.Opt
}
drv := &Driver{
root: root,
statePath: filepath.Join(cacheDir, stateFile),
volumes: map[string]*Volume{},
mntOpt: *mntOpt,
vfsOpt: *vfsOpt,
dummy: dummy,
}
drv.mntOpt.Daemon = false
// restore from saved state
if !forgetState {
if err = drv.restoreState(ctx); err != nil {
return nil, fmt.Errorf("failed to restore state: %w", err)
}
}
// start mount monitoring
drv.hupChan = make(chan os.Signal, 1)
drv.monChan = make(chan bool, 1)
mountlib.NotifyOnSigHup(drv.hupChan)
go drv.monitor()
// unmount all volumes on exit
atexit.Register(func() {
drv.exitOnce.Do(drv.Exit)
})
// notify systemd
if _, err := daemon.SdNotify(false, daemon.SdNotifyReady); err != nil {
return nil, fmt.Errorf("failed to notify systemd: %w", err)
}
return drv, nil
}
// Exit will unmount all currently mounted volumes
func (drv *Driver) Exit() {
fs.Debugf(nil, "Unmount all volumes")
drv.mu.Lock()
defer drv.mu.Unlock()
reportErr(func() error {
_, err := daemon.SdNotify(false, daemon.SdNotifyStopping)
return err
}())
drv.monChan <- true // ask monitor to exit
for _, vol := range drv.volumes {
reportErr(vol.unmountAll())
vol.Mounts = []string{} // never persist mounts at exit
}
reportErr(drv.saveState())
drv.dummy = true // no more mounts
}
// monitor all mounts
func (drv *Driver) monitor() {
for {
// https://stackoverflow.com/questions/19992334/how-to-listen-to-n-channels-dynamic-select-statement
monChan := reflect.SelectCase{
Dir: reflect.SelectRecv,
Chan: reflect.ValueOf(drv.monChan),
}
hupChan := reflect.SelectCase{
Dir: reflect.SelectRecv,
Chan: reflect.ValueOf(drv.monChan),
}
sources := []reflect.SelectCase{monChan, hupChan}
volumes := []*Volume{nil, nil}
drv.mu.Lock()
for _, vol := range drv.volumes {
if vol.mnt.ErrChan != nil {
errSource := reflect.SelectCase{
Dir: reflect.SelectRecv,
Chan: reflect.ValueOf(vol.mnt.ErrChan),
}
sources = append(sources, errSource)
volumes = append(volumes, vol)
}
}
drv.mu.Unlock()
fs.Debugf(nil, "Monitoring %d volumes", len(sources)-2)
idx, val, _ := reflect.Select(sources)
switch idx {
case 0:
if val.Bool() {
fs.Debugf(nil, "Monitoring stopped")
return
}
case 1:
// user sent SIGHUP to clear the cache
drv.clearCache()
default:
vol := volumes[idx]
if err := val.Interface(); err != nil {
fs.Logf(nil, "Volume %q unmounted externally: %v", vol.Name, err)
} else {
fs.Infof(nil, "Volume %q unmounted externally", vol.Name)
}
drv.mu.Lock()
reportErr(vol.unmountAll())
drv.mu.Unlock()
}
}
}
// clearCache will clear cache of all volumes
func (drv *Driver) clearCache() {
fs.Debugf(nil, "Clear all caches")
drv.mu.Lock()
defer drv.mu.Unlock()
for _, vol := range drv.volumes {
reportErr(vol.clearCache())
}
}
func reportErr(err error) {
if err != nil {
fs.Errorf("docker plugin", "%v", err)
}
}
// Create volume
// To use subpath we are limited to defining a new volume definition via alias
func (drv *Driver) Create(req *CreateRequest) error {
ctx := context.Background()
drv.mu.Lock()
defer drv.mu.Unlock()
name := req.Name
fs.Debugf(nil, "Create volume %q", name)
if vol, _ := drv.getVolume(name); vol != nil {
return ErrVolumeExists
}
vol, err := newVolume(ctx, name, req.Options, drv)
if err != nil {
return err
}
drv.volumes[name] = vol
return drv.saveState()
}
// Remove volume
func (drv *Driver) Remove(req *RemoveRequest) error {
ctx := context.Background()
drv.mu.Lock()
defer drv.mu.Unlock()
vol, err := drv.getVolume(req.Name)
if err != nil {
return err
}
if err = vol.remove(ctx); err != nil {
return err
}
delete(drv.volumes, vol.Name)
return drv.saveState()
}
// List volumes handled by the driver
func (drv *Driver) List() (*ListResponse, error) {
drv.mu.Lock()
defer drv.mu.Unlock()
volumeList := drv.listVolumes()
fs.Debugf(nil, "List: %v", volumeList)
res := &ListResponse{
Volumes: []*VolInfo{},
}
for _, name := range volumeList {
vol := drv.volumes[name]
res.Volumes = append(res.Volumes, vol.getInfo())
}
return res, nil
}
// Get volume info
func (drv *Driver) Get(req *GetRequest) (*GetResponse, error) {
drv.mu.Lock()
defer drv.mu.Unlock()
vol, err := drv.getVolume(req.Name)
if err != nil {
return nil, err
}
return &GetResponse{Volume: vol.getInfo()}, nil
}
// Path returns path of the requested volume
func (drv *Driver) Path(req *PathRequest) (*PathResponse, error) {
drv.mu.Lock()
defer drv.mu.Unlock()
vol, err := drv.getVolume(req.Name)
if err != nil {
return nil, err
}
return &PathResponse{Mountpoint: vol.MountPoint}, nil
}
// Mount volume
func (drv *Driver) Mount(req *MountRequest) (*MountResponse, error) {
drv.mu.Lock()
defer drv.mu.Unlock()
vol, err := drv.getVolume(req.Name)
if err == nil {
err = vol.mount(req.ID)
}
if err == nil {
err = drv.saveState()
}
if err != nil {
return nil, err
}
return &MountResponse{Mountpoint: vol.MountPoint}, nil
}
// Unmount volume
func (drv *Driver) Unmount(req *UnmountRequest) error {
drv.mu.Lock()
defer drv.mu.Unlock()
vol, err := drv.getVolume(req.Name)
if err == nil {
err = vol.unmount(req.ID)
}
if err == nil {
err = drv.saveState()
}
return err
}
// getVolume returns volume by name
func (drv *Driver) getVolume(name string) (*Volume, error) {
vol := drv.volumes[name]
if vol == nil {
return nil, ErrVolumeNotFound
}
return vol, nil
}
// listVolumes returns list volume listVolumes
func (drv *Driver) listVolumes() []string {
names := []string{}
for key := range drv.volumes {
names = append(names, key)
}
sort.Strings(names)
return names
}
// saveState saves volumes handled by driver to persistent store
func (drv *Driver) saveState() error {
volumeList := drv.listVolumes()
fs.Debugf(nil, "Save state %v to %s", volumeList, drv.statePath)
state := []*Volume{}
for _, key := range volumeList {
vol := drv.volumes[key]
vol.prepareState()
state = append(state, vol)
}
data, err := json.Marshal(state)
if err != nil {
return fmt.Errorf("failed to marshal state: %w", err)
}
ctx := context.Background()
retries := fs.GetConfig(ctx).LowLevelRetries
for i := 0; i <= retries; i++ {
err = os.WriteFile(drv.statePath, data, 0600)
if err == nil {
return nil
}
time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
}
return fmt.Errorf("failed to save state: %w", err)
}
// restoreState recreates volumes from saved driver state
func (drv *Driver) restoreState(ctx context.Context) error {
fs.Debugf(nil, "Restore state from %s", drv.statePath)
data, err := os.ReadFile(drv.statePath)
if os.IsNotExist(err) {
return nil
}
var state []*Volume
if err == nil {
err = json.Unmarshal(data, &state)
}
if err != nil {
fs.Logf(nil, "Failed to restore plugin state: %v", err)
return nil
}
for _, vol := range state {
if err := vol.restoreState(ctx, drv); err != nil {
fs.Logf(nil, "Failed to restore volume %q: %v", vol.Name, err)
continue
}
drv.volumes[vol.Name] = vol
}
return nil
}