Vendor integration dependencies.

integration/vendor/github.com/docker/libkv/store/etcd/etcd.go

@@ -0,0 +1,606 @@
+package etcd
+
+import (
+	"crypto/tls"
+	"errors"
+	"log"
+	"net"
+	"net/http"
+	"strings"
+	"time"
+
+	"golang.org/x/net/context"
+
+	etcd "github.com/coreos/etcd/client"
+	"github.com/docker/libkv"
+	"github.com/docker/libkv/store"
+)
+
+var (
+	// ErrAbortTryLock is thrown when a user stops trying to seek the lock
+	// by sending a signal to the stop chan, this is used to verify if the
+	// operation succeeded
+	ErrAbortTryLock = errors.New("lock operation aborted")
+)
+
+// Etcd is the receiver type for the
+// Store interface
+type Etcd struct {
+	client etcd.KeysAPI
+}
+
+type etcdLock struct {
+	client    etcd.KeysAPI
+	stopLock  chan struct{}
+	stopRenew chan struct{}
+	key       string
+	value     string
+	last      *etcd.Response
+	ttl       time.Duration
+}
+
+const (
+	periodicSync      = 5 * time.Minute
+	defaultLockTTL    = 20 * time.Second
+	defaultUpdateTime = 5 * time.Second
+)
+
+// Register registers etcd to libkv
+func Register() {
+	libkv.AddStore(store.ETCD, New)
+}
+
+// New creates a new Etcd client given a list
+// of endpoints and an optional tls config
+func New(addrs []string, options *store.Config) (store.Store, error) {
+	s := &Etcd{}
+
+	var (
+		entries []string
+		err     error
+	)
+
+	entries = store.CreateEndpoints(addrs, "http")
+	cfg := &etcd.Config{
+		Endpoints:               entries,
+		Transport:               etcd.DefaultTransport,
+		HeaderTimeoutPerRequest: 3 * time.Second,
+	}
+
+	// Set options
+	if options != nil {
+		if options.TLS != nil {
+			setTLS(cfg, options.TLS, addrs)
+		}
+		if options.ConnectionTimeout != 0 {
+			setTimeout(cfg, options.ConnectionTimeout)
+		}
+		if options.Username != "" {
+			setCredentials(cfg, options.Username, options.Password)
+		}
+	}
+
+	c, err := etcd.New(*cfg)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	s.client = etcd.NewKeysAPI(c)
+
+	// Periodic Cluster Sync
+	go func() {
+		for {
+			if err := c.AutoSync(context.Background(), periodicSync); err != nil {
+				return
+			}
+		}
+	}()
+
+	return s, nil
+}
+
+// SetTLS sets the tls configuration given a tls.Config scheme
+func setTLS(cfg *etcd.Config, tls *tls.Config, addrs []string) {
+	entries := store.CreateEndpoints(addrs, "https")
+	cfg.Endpoints = entries
+
+	// Set transport
+	t := http.Transport{
+		Dial: (&net.Dialer{
+			Timeout:   30 * time.Second,
+			KeepAlive: 30 * time.Second,
+		}).Dial,
+		TLSHandshakeTimeout: 10 * time.Second,
+		TLSClientConfig:     tls,
+	}
+
+	cfg.Transport = &t
+}
+
+// setTimeout sets the timeout used for connecting to the store
+func setTimeout(cfg *etcd.Config, time time.Duration) {
+	cfg.HeaderTimeoutPerRequest = time
+}
+
+// setCredentials sets the username/password credentials for connecting to Etcd
+func setCredentials(cfg *etcd.Config, username, password string) {
+	cfg.Username = username
+	cfg.Password = password
+}
+
+// Normalize the key for usage in Etcd
+func (s *Etcd) normalize(key string) string {
+	key = store.Normalize(key)
+	return strings.TrimPrefix(key, "/")
+}
+
+// keyNotFound checks on the error returned by the KeysAPI
+// to verify if the key exists in the store or not
+func keyNotFound(err error) bool {
+	if err != nil {
+		if etcdError, ok := err.(etcd.Error); ok {
+			if etcdError.Code == etcd.ErrorCodeKeyNotFound ||
+				etcdError.Code == etcd.ErrorCodeNotFile ||
+				etcdError.Code == etcd.ErrorCodeNotDir {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// Get the value at "key", returns the last modified
+// index to use in conjunction to Atomic calls
+func (s *Etcd) Get(key string) (pair *store.KVPair, err error) {
+	getOpts := &etcd.GetOptions{
+		Quorum: true,
+	}
+
+	result, err := s.client.Get(context.Background(), s.normalize(key), getOpts)
+	if err != nil {
+		if keyNotFound(err) {
+			return nil, store.ErrKeyNotFound
+		}
+		return nil, err
+	}
+
+	pair = &store.KVPair{
+		Key:       key,
+		Value:     []byte(result.Node.Value),
+		LastIndex: result.Node.ModifiedIndex,
+	}
+
+	return pair, nil
+}
+
+// Put a value at "key"
+func (s *Etcd) Put(key string, value []byte, opts *store.WriteOptions) error {
+	setOpts := &etcd.SetOptions{}
+
+	// Set options
+	if opts != nil {
+		setOpts.Dir = opts.IsDir
+		setOpts.TTL = opts.TTL
+	}
+
+	_, err := s.client.Set(context.Background(), s.normalize(key), string(value), setOpts)
+	return err
+}
+
+// Delete a value at "key"
+func (s *Etcd) Delete(key string) error {
+	opts := &etcd.DeleteOptions{
+		Recursive: false,
+	}
+
+	_, err := s.client.Delete(context.Background(), s.normalize(key), opts)
+	if keyNotFound(err) {
+		return store.ErrKeyNotFound
+	}
+	return err
+}
+
+// Exists checks if the key exists inside the store
+func (s *Etcd) Exists(key string) (bool, error) {
+	_, err := s.Get(key)
+	if err != nil {
+		if err == store.ErrKeyNotFound {
+			return false, nil
+		}
+		return false, err
+	}
+	return true, nil
+}
+
+// Watch for changes on a "key"
+// It returns a channel that will receive changes or pass
+// on errors. Upon creation, the current value will first
+// be sent to the channel. Providing a non-nil stopCh can
+// be used to stop watching.
+func (s *Etcd) Watch(key string, stopCh <-chan struct{}) (<-chan *store.KVPair, error) {
+	opts := &etcd.WatcherOptions{Recursive: false}
+	watcher := s.client.Watcher(s.normalize(key), opts)
+
+	// watchCh is sending back events to the caller
+	watchCh := make(chan *store.KVPair)
+
+	go func() {
+		defer close(watchCh)
+
+		// Get the current value
+		pair, err := s.Get(key)
+		if err != nil {
+			return
+		}
+
+		// Push the current value through the channel.
+		watchCh <- pair
+
+		for {
+			// Check if the watch was stopped by the caller
+			select {
+			case <-stopCh:
+				return
+			default:
+			}
+
+			result, err := watcher.Next(context.Background())
+
+			if err != nil {
+				return
+			}
+
+			watchCh <- &store.KVPair{
+				Key:       key,
+				Value:     []byte(result.Node.Value),
+				LastIndex: result.Node.ModifiedIndex,
+			}
+		}
+	}()
+
+	return watchCh, nil
+}
+
+// WatchTree watches for changes on a "directory"
+// It returns a channel that will receive changes or pass
+// on errors. Upon creating a watch, the current childs values
+// will be sent to the channel. Providing a non-nil stopCh can
+// be used to stop watching.
+func (s *Etcd) WatchTree(directory string, stopCh <-chan struct{}) (<-chan []*store.KVPair, error) {
+	watchOpts := &etcd.WatcherOptions{Recursive: true}
+	watcher := s.client.Watcher(s.normalize(directory), watchOpts)
+
+	// watchCh is sending back events to the caller
+	watchCh := make(chan []*store.KVPair)
+
+	go func() {
+		defer close(watchCh)
+
+		// Get child values
+		list, err := s.List(directory)
+		if err != nil {
+			return
+		}
+
+		// Push the current value through the channel.
+		watchCh <- list
+
+		for {
+			// Check if the watch was stopped by the caller
+			select {
+			case <-stopCh:
+				return
+			default:
+			}
+
+			_, err := watcher.Next(context.Background())
+
+			if err != nil {
+				return
+			}
+
+			list, err = s.List(directory)
+			if err != nil {
+				return
+			}
+
+			watchCh <- list
+		}
+	}()
+
+	return watchCh, nil
+}
+
+// AtomicPut puts a value at "key" if the key has not been
+// modified in the meantime, throws an error if this is the case
+func (s *Etcd) AtomicPut(key string, value []byte, previous *store.KVPair, opts *store.WriteOptions) (bool, *store.KVPair, error) {
+	var (
+		meta *etcd.Response
+		err  error
+	)
+
+	setOpts := &etcd.SetOptions{}
+
+	if previous != nil {
+		setOpts.PrevExist = etcd.PrevExist
+		setOpts.PrevIndex = previous.LastIndex
+		if previous.Value != nil {
+			setOpts.PrevValue = string(previous.Value)
+		}
+	} else {
+		setOpts.PrevExist = etcd.PrevNoExist
+	}
+
+	if opts != nil {
+		if opts.TTL > 0 {
+			setOpts.TTL = opts.TTL
+		}
+	}
+
+	meta, err = s.client.Set(context.Background(), s.normalize(key), string(value), setOpts)
+	if err != nil {
+		if etcdError, ok := err.(etcd.Error); ok {
+			// Compare failed
+			if etcdError.Code == etcd.ErrorCodeTestFailed {
+				return false, nil, store.ErrKeyModified
+			}
+			// Node exists error (when PrevNoExist)
+			if etcdError.Code == etcd.ErrorCodeNodeExist {
+				return false, nil, store.ErrKeyExists
+			}
+		}
+		return false, nil, err
+	}
+
+	updated := &store.KVPair{
+		Key:       key,
+		Value:     value,
+		LastIndex: meta.Node.ModifiedIndex,
+	}
+
+	return true, updated, nil
+}
+
+// AtomicDelete deletes a value at "key" if the key
+// has not been modified in the meantime, throws an
+// error if this is the case
+func (s *Etcd) AtomicDelete(key string, previous *store.KVPair) (bool, error) {
+	if previous == nil {
+		return false, store.ErrPreviousNotSpecified
+	}
+
+	delOpts := &etcd.DeleteOptions{}
+
+	if previous != nil {
+		delOpts.PrevIndex = previous.LastIndex
+		if previous.Value != nil {
+			delOpts.PrevValue = string(previous.Value)
+		}
+	}
+
+	_, err := s.client.Delete(context.Background(), s.normalize(key), delOpts)
+	if err != nil {
+		if etcdError, ok := err.(etcd.Error); ok {
+			// Key Not Found
+			if etcdError.Code == etcd.ErrorCodeKeyNotFound {
+				return false, store.ErrKeyNotFound
+			}
+			// Compare failed
+			if etcdError.Code == etcd.ErrorCodeTestFailed {
+				return false, store.ErrKeyModified
+			}
+		}
+		return false, err
+	}
+
+	return true, nil
+}
+
+// List child nodes of a given directory
+func (s *Etcd) List(directory string) ([]*store.KVPair, error) {
+	getOpts := &etcd.GetOptions{
+		Quorum:    true,
+		Recursive: true,
+		Sort:      true,
+	}
+
+	resp, err := s.client.Get(context.Background(), s.normalize(directory), getOpts)
+	if err != nil {
+		if keyNotFound(err) {
+			return nil, store.ErrKeyNotFound
+		}
+		return nil, err
+	}
+
+	kv := []*store.KVPair{}
+	for _, n := range resp.Node.Nodes {
+		kv = append(kv, &store.KVPair{
+			Key:       n.Key,
+			Value:     []byte(n.Value),
+			LastIndex: n.ModifiedIndex,
+		})
+	}
+	return kv, nil
+}
+
+// DeleteTree deletes a range of keys under a given directory
+func (s *Etcd) DeleteTree(directory string) error {
+	delOpts := &etcd.DeleteOptions{
+		Recursive: true,
+	}
+
+	_, err := s.client.Delete(context.Background(), s.normalize(directory), delOpts)
+	if keyNotFound(err) {
+		return store.ErrKeyNotFound
+	}
+	return err
+}
+
+// NewLock returns a handle to a lock struct which can
+// be used to provide mutual exclusion on a key
+func (s *Etcd) NewLock(key string, options *store.LockOptions) (lock store.Locker, err error) {
+	var value string
+	ttl := defaultLockTTL
+	renewCh := make(chan struct{})
+
+	// Apply options on Lock
+	if options != nil {
+		if options.Value != nil {
+			value = string(options.Value)
+		}
+		if options.TTL != 0 {
+			ttl = options.TTL
+		}
+		if options.RenewLock != nil {
+			renewCh = options.RenewLock
+		}
+	}
+
+	// Create lock object
+	lock = &etcdLock{
+		client:    s.client,
+		stopRenew: renewCh,
+		key:       s.normalize(key),
+		value:     value,
+		ttl:       ttl,
+	}
+
+	return lock, nil
+}
+
+// Lock attempts to acquire the lock and blocks while
+// doing so. It returns a channel that is closed if our
+// lock is lost or if an error occurs
+func (l *etcdLock) Lock(stopChan chan struct{}) (<-chan struct{}, error) {
+
+	// Lock holder channel
+	lockHeld := make(chan struct{})
+	stopLocking := l.stopRenew
+
+	setOpts := &etcd.SetOptions{
+		TTL: l.ttl,
+	}
+
+	for {
+		setOpts.PrevExist = etcd.PrevNoExist
+		resp, err := l.client.Set(context.Background(), l.key, l.value, setOpts)
+		if err != nil {
+			if etcdError, ok := err.(etcd.Error); ok {
+				if etcdError.Code != etcd.ErrorCodeNodeExist {
+					return nil, err
+				}
+				setOpts.PrevIndex = ^uint64(0)
+			}
+		} else {
+			setOpts.PrevIndex = resp.Node.ModifiedIndex
+		}
+
+		setOpts.PrevExist = etcd.PrevExist
+		l.last, err = l.client.Set(context.Background(), l.key, l.value, setOpts)
+
+		if err == nil {
+			// Leader section
+			l.stopLock = stopLocking
+			go l.holdLock(l.key, lockHeld, stopLocking)
+			break
+		} else {
+			// If this is a legitimate error, return
+			if etcdError, ok := err.(etcd.Error); ok {
+				if etcdError.Code != etcd.ErrorCodeTestFailed {
+					return nil, err
+				}
+			}
+
+			// Seeker section
+			errorCh := make(chan error)
+			chWStop := make(chan bool)
+			free := make(chan bool)
+
+			go l.waitLock(l.key, errorCh, chWStop, free)
+
+			// Wait for the key to be available or for
+			// a signal to stop trying to lock the key
+			select {
+			case <-free:
+				break
+			case err := <-errorCh:
+				return nil, err
+			case <-stopChan:
+				return nil, ErrAbortTryLock
+			}
+
+			// Delete or Expire event occurred
+			// Retry
+		}
+	}
+
+	return lockHeld, nil
+}
+
+// Hold the lock as long as we can
+// Updates the key ttl periodically until we receive
+// an explicit stop signal from the Unlock method
+func (l *etcdLock) holdLock(key string, lockHeld chan struct{}, stopLocking <-chan struct{}) {
+	defer close(lockHeld)
+
+	update := time.NewTicker(l.ttl / 3)
+	defer update.Stop()
+
+	var err error
+	setOpts := &etcd.SetOptions{TTL: l.ttl}
+
+	for {
+		select {
+		case <-update.C:
+			setOpts.PrevIndex = l.last.Node.ModifiedIndex
+			l.last, err = l.client.Set(context.Background(), key, l.value, setOpts)
+			if err != nil {
+				return
+			}
+
+		case <-stopLocking:
+			return
+		}
+	}
+}
+
+// WaitLock simply waits for the key to be available for creation
+func (l *etcdLock) waitLock(key string, errorCh chan error, stopWatchCh chan bool, free chan<- bool) {
+	opts := &etcd.WatcherOptions{Recursive: false}
+	watcher := l.client.Watcher(key, opts)
+
+	for {
+		event, err := watcher.Next(context.Background())
+		if err != nil {
+			errorCh <- err
+			return
+		}
+		if event.Action == "delete" || event.Action == "expire" {
+			free <- true
+			return
+		}
+	}
+}
+
+// Unlock the "key". Calling unlock while
+// not holding the lock will throw an error
+func (l *etcdLock) Unlock() error {
+	if l.stopLock != nil {
+		l.stopLock <- struct{}{}
+	}
+	if l.last != nil {
+		delOpts := &etcd.DeleteOptions{
+			PrevIndex: l.last.Node.ModifiedIndex,
+		}
+		_, err := l.client.Delete(context.Background(), l.key, delOpts)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Close closes the client connection
+func (s *Etcd) Close() {
+	return
+}