diff --git a/vendor/github.com/hashicorp/consul/api/lock.go b/vendor/github.com/hashicorp/consul/api/lock.go
new file mode 100644
index 0000000..82339cb
--- /dev/null
+++ b/vendor/github.com/hashicorp/consul/api/lock.go
@@ -0,0 +1,386 @@
+package api
+
+import (
+	"fmt"
+	"sync"
+	"time"
+)
+
+const (
+	// DefaultLockSessionName is the Session Name we assign if none is provided
+	DefaultLockSessionName = "Consul API Lock"
+
+	// DefaultLockSessionTTL is the default session TTL if no Session is provided
+	// when creating a new Lock. This is used because we do not have another
+	// other check to depend upon.
+	DefaultLockSessionTTL = "15s"
+
+	// DefaultLockWaitTime is how long we block for at a time to check if lock
+	// acquisition is possible. This affects the minimum time it takes to cancel
+	// a Lock acquisition.
+	DefaultLockWaitTime = 15 * time.Second
+
+	// DefaultLockRetryTime is how long we wait after a failed lock acquisition
+	// before attempting to do the lock again. This is so that once a lock-delay
+	// is in effect, we do not hot loop retrying the acquisition.
+	DefaultLockRetryTime = 5 * time.Second
+
+	// DefaultMonitorRetryTime is how long we wait after a failed monitor check
+	// of a lock (500 response code). This allows the monitor to ride out brief
+	// periods of unavailability, subject to the MonitorRetries setting in the
+	// lock options which is by default set to 0, disabling this feature. This
+	// affects locks and semaphores.
+	DefaultMonitorRetryTime = 2 * time.Second
+
+	// LockFlagValue is a magic flag we set to indicate a key
+	// is being used for a lock. It is used to detect a potential
+	// conflict with a semaphore.
+	LockFlagValue = 0x2ddccbc058a50c18
+)
+
+var (
+	// ErrLockHeld is returned if we attempt to double lock
+	ErrLockHeld = fmt.Errorf("Lock already held")
+
+	// ErrLockNotHeld is returned if we attempt to unlock a lock
+	// that we do not hold.
+	ErrLockNotHeld = fmt.Errorf("Lock not held")
+
+	// ErrLockInUse is returned if we attempt to destroy a lock
+	// that is in use.
+	ErrLockInUse = fmt.Errorf("Lock in use")
+
+	// ErrLockConflict is returned if the flags on a key
+	// used for a lock do not match expectation
+	ErrLockConflict = fmt.Errorf("Existing key does not match lock use")
+)
+
+// Lock is used to implement client-side leader election. It is follows the
+// algorithm as described here: https://www.consul.io/docs/guides/leader-election.html.
+type Lock struct {
+	c    *Client
+	opts *LockOptions
+
+	isHeld       bool
+	sessionRenew chan struct{}
+	lockSession  string
+	l            sync.Mutex
+}
+
+// LockOptions is used to parameterize the Lock behavior.
+type LockOptions struct {
+	Key              string        // Must be set and have write permissions
+	Value            []byte        // Optional, value to associate with the lock
+	Session          string        // Optional, created if not specified
+	SessionOpts      *SessionEntry // Optional, options to use when creating a session
+	SessionName      string        // Optional, defaults to DefaultLockSessionName (ignored if SessionOpts is given)
+	SessionTTL       string        // Optional, defaults to DefaultLockSessionTTL (ignored if SessionOpts is given)
+	MonitorRetries   int           // Optional, defaults to 0 which means no retries
+	MonitorRetryTime time.Duration // Optional, defaults to DefaultMonitorRetryTime
+	LockWaitTime     time.Duration // Optional, defaults to DefaultLockWaitTime
+	LockTryOnce      bool          // Optional, defaults to false which means try forever
+}
+
+// LockKey returns a handle to a lock struct which can be used
+// to acquire and release the mutex. The key used must have
+// write permissions.
+func (c *Client) LockKey(key string) (*Lock, error) {
+	opts := &LockOptions{
+		Key: key,
+	}
+	return c.LockOpts(opts)
+}
+
+// LockOpts returns a handle to a lock struct which can be used
+// to acquire and release the mutex. The key used must have
+// write permissions.
+func (c *Client) LockOpts(opts *LockOptions) (*Lock, error) {
+	if opts.Key == "" {
+		return nil, fmt.Errorf("missing key")
+	}
+	if opts.SessionName == "" {
+		opts.SessionName = DefaultLockSessionName
+	}
+	if opts.SessionTTL == "" {
+		opts.SessionTTL = DefaultLockSessionTTL
+	} else {
+		if _, err := time.ParseDuration(opts.SessionTTL); err != nil {
+			return nil, fmt.Errorf("invalid SessionTTL: %v", err)
+		}
+	}
+	if opts.MonitorRetryTime == 0 {
+		opts.MonitorRetryTime = DefaultMonitorRetryTime
+	}
+	if opts.LockWaitTime == 0 {
+		opts.LockWaitTime = DefaultLockWaitTime
+	}
+	l := &Lock{
+		c:    c,
+		opts: opts,
+	}
+	return l, nil
+}
+
+// Lock attempts to acquire the lock and blocks while doing so.
+// Providing a non-nil stopCh can be used to abort the lock attempt.
+// Returns a channel that is closed if our lock is lost or an error.
+// This channel could be closed at any time due to session invalidation,
+// communication errors, operator intervention, etc. It is NOT safe to
+// assume that the lock is held until Unlock() unless the Session is specifically
+// created without any associated health checks. By default Consul sessions
+// prefer liveness over safety and an application must be able to handle
+// the lock being lost.
+func (l *Lock) Lock(stopCh <-chan struct{}) (<-chan struct{}, error) {
+	// Hold the lock as we try to acquire
+	l.l.Lock()
+	defer l.l.Unlock()
+
+	// Check if we already hold the lock
+	if l.isHeld {
+		return nil, ErrLockHeld
+	}
+
+	// Check if we need to create a session first
+	l.lockSession = l.opts.Session
+	if l.lockSession == "" {
+		s, err := l.createSession()
+		if err != nil {
+			return nil, fmt.Errorf("failed to create session: %v", err)
+		}
+
+		l.sessionRenew = make(chan struct{})
+		l.lockSession = s
+		session := l.c.Session()
+		go session.RenewPeriodic(l.opts.SessionTTL, s, nil, l.sessionRenew)
+
+		// If we fail to acquire the lock, cleanup the session
+		defer func() {
+			if !l.isHeld {
+				close(l.sessionRenew)
+				l.sessionRenew = nil
+			}
+		}()
+	}
+
+	// Setup the query options
+	kv := l.c.KV()
+	qOpts := &QueryOptions{
+		WaitTime: l.opts.LockWaitTime,
+	}
+
+	start := time.Now()
+	attempts := 0
+WAIT:
+	// Check if we should quit
+	select {
+	case <-stopCh:
+		return nil, nil
+	default:
+	}
+
+	// Handle the one-shot mode.
+	if l.opts.LockTryOnce && attempts > 0 {
+		elapsed := time.Since(start)
+		if elapsed > l.opts.LockWaitTime {
+			return nil, nil
+		}
+
+		// Query wait time should not exceed the lock wait time
+		qOpts.WaitTime = l.opts.LockWaitTime - elapsed
+	}
+	attempts++
+
+	// Look for an existing lock, blocking until not taken
+	pair, meta, err := kv.Get(l.opts.Key, qOpts)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read lock: %v", err)
+	}
+	if pair != nil && pair.Flags != LockFlagValue {
+		return nil, ErrLockConflict
+	}
+	locked := false
+	if pair != nil && pair.Session == l.lockSession {
+		goto HELD
+	}
+	if pair != nil && pair.Session != "" {
+		qOpts.WaitIndex = meta.LastIndex
+		goto WAIT
+	}
+
+	// Try to acquire the lock
+	pair = l.lockEntry(l.lockSession)
+	locked, _, err = kv.Acquire(pair, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to acquire lock: %v", err)
+	}
+
+	// Handle the case of not getting the lock
+	if !locked {
+		// Determine why the lock failed
+		qOpts.WaitIndex = 0
+		pair, meta, err = kv.Get(l.opts.Key, qOpts)
+		if pair != nil && pair.Session != "" {
+			//If the session is not null, this means that a wait can safely happen
+			//using a long poll
+			qOpts.WaitIndex = meta.LastIndex
+			goto WAIT
+		} else {
+			// If the session is empty and the lock failed to acquire, then it means
+			// a lock-delay is in effect and a timed wait must be used
+			select {
+			case <-time.After(DefaultLockRetryTime):
+				goto WAIT
+			case <-stopCh:
+				return nil, nil
+			}
+		}
+	}
+
+HELD:
+	// Watch to ensure we maintain leadership
+	leaderCh := make(chan struct{})
+	go l.monitorLock(l.lockSession, leaderCh)
+
+	// Set that we own the lock
+	l.isHeld = true
+
+	// Locked! All done
+	return leaderCh, nil
+}
+
+// Unlock released the lock. It is an error to call this
+// if the lock is not currently held.
+func (l *Lock) Unlock() error {
+	// Hold the lock as we try to release
+	l.l.Lock()
+	defer l.l.Unlock()
+
+	// Ensure the lock is actually held
+	if !l.isHeld {
+		return ErrLockNotHeld
+	}
+
+	// Set that we no longer own the lock
+	l.isHeld = false
+
+	// Stop the session renew
+	if l.sessionRenew != nil {
+		defer func() {
+			close(l.sessionRenew)
+			l.sessionRenew = nil
+		}()
+	}
+
+	// Get the lock entry, and clear the lock session
+	lockEnt := l.lockEntry(l.lockSession)
+	l.lockSession = ""
+
+	// Release the lock explicitly
+	kv := l.c.KV()
+	_, _, err := kv.Release(lockEnt, nil)
+	if err != nil {
+		return fmt.Errorf("failed to release lock: %v", err)
+	}
+	return nil
+}
+
+// Destroy is used to cleanup the lock entry. It is not necessary
+// to invoke. It will fail if the lock is in use.
+func (l *Lock) Destroy() error {
+	// Hold the lock as we try to release
+	l.l.Lock()
+	defer l.l.Unlock()
+
+	// Check if we already hold the lock
+	if l.isHeld {
+		return ErrLockHeld
+	}
+
+	// Look for an existing lock
+	kv := l.c.KV()
+	pair, _, err := kv.Get(l.opts.Key, nil)
+	if err != nil {
+		return fmt.Errorf("failed to read lock: %v", err)
+	}
+
+	// Nothing to do if the lock does not exist
+	if pair == nil {
+		return nil
+	}
+
+	// Check for possible flag conflict
+	if pair.Flags != LockFlagValue {
+		return ErrLockConflict
+	}
+
+	// Check if it is in use
+	if pair.Session != "" {
+		return ErrLockInUse
+	}
+
+	// Attempt the delete
+	didRemove, _, err := kv.DeleteCAS(pair, nil)
+	if err != nil {
+		return fmt.Errorf("failed to remove lock: %v", err)
+	}
+	if !didRemove {
+		return ErrLockInUse
+	}
+	return nil
+}
+
+// createSession is used to create a new managed session
+func (l *Lock) createSession() (string, error) {
+	session := l.c.Session()
+	se := l.opts.SessionOpts
+	if se == nil {
+		se = &SessionEntry{
+			Name: l.opts.SessionName,
+			TTL:  l.opts.SessionTTL,
+		}
+	}
+	id, _, err := session.Create(se, nil)
+	if err != nil {
+		return "", err
+	}
+	return id, nil
+}
+
+// lockEntry returns a formatted KVPair for the lock
+func (l *Lock) lockEntry(session string) *KVPair {
+	return &KVPair{
+		Key:     l.opts.Key,
+		Value:   l.opts.Value,
+		Session: session,
+		Flags:   LockFlagValue,
+	}
+}
+
+// monitorLock is a long running routine to monitor a lock ownership
+// It closes the stopCh if we lose our leadership.
+func (l *Lock) monitorLock(session string, stopCh chan struct{}) {
+	defer close(stopCh)
+	kv := l.c.KV()
+	opts := &QueryOptions{RequireConsistent: true}
+WAIT:
+	retries := l.opts.MonitorRetries
+RETRY:
+	pair, meta, err := kv.Get(l.opts.Key, opts)
+	if err != nil {
+		// If configured we can try to ride out a brief Consul unavailability
+		// by doing retries. Note that we have to attempt the retry in a non-
+		// blocking fashion so that we have a clean place to reset the retry
+		// counter if service is restored.
+		if retries > 0 && IsRetryableError(err) {
+			time.Sleep(l.opts.MonitorRetryTime)
+			retries--
+			opts.WaitIndex = 0
+			goto RETRY
+		}
+		return
+	}
+	if pair != nil && pair.Session == session {
+		opts.WaitIndex = meta.LastIndex
+		goto WAIT
+	}
+}