diff --git a/vendor/github.com/xiang90/probing/prober.go b/vendor/github.com/xiang90/probing/prober.go
new file mode 100644
index 0000000..9431c10
--- /dev/null
+++ b/vendor/github.com/xiang90/probing/prober.go
@@ -0,0 +1,139 @@
+package probing
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"sync"
+	"time"
+)
+
+var (
+	ErrNotFound = errors.New("probing: id not found")
+	ErrExist    = errors.New("probing: id exists")
+)
+
+type Prober interface {
+	AddHTTP(id string, probingInterval time.Duration, endpoints []string) error
+	Remove(id string) error
+	RemoveAll()
+	Reset(id string) error
+	Status(id string) (Status, error)
+}
+
+type prober struct {
+	mu      sync.Mutex
+	targets map[string]*status
+	tr      http.RoundTripper
+}
+
+func NewProber(tr http.RoundTripper) Prober {
+	p := &prober{targets: make(map[string]*status)}
+	if tr == nil {
+		p.tr = http.DefaultTransport
+	} else {
+		p.tr = tr
+	}
+	return p
+}
+
+func (p *prober) AddHTTP(id string, probingInterval time.Duration, endpoints []string) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if _, ok := p.targets[id]; ok {
+		return ErrExist
+	}
+
+	s := &status{stopC: make(chan struct{})}
+	p.targets[id] = s
+
+	ticker := time.NewTicker(probingInterval)
+
+	go func() {
+		pinned := 0
+		for {
+			select {
+			case <-ticker.C:
+				start := time.Now()
+				req, err := http.NewRequest("GET", endpoints[pinned], nil)
+				if err != nil {
+					panic(err)
+				}
+				resp, err := p.tr.RoundTrip(req)
+				if err == nil && resp.StatusCode != http.StatusOK {
+					err = fmt.Errorf("got unexpected HTTP status code %s from %s", resp.Status, endpoints[pinned])
+					resp.Body.Close()
+				}
+				if err != nil {
+					s.recordFailure(err)
+					pinned = (pinned + 1) % len(endpoints)
+					continue
+				}
+
+				var hh Health
+				d := json.NewDecoder(resp.Body)
+				err = d.Decode(&hh)
+				resp.Body.Close()
+				if err != nil || !hh.OK {
+					s.recordFailure(err)
+					pinned = (pinned + 1) % len(endpoints)
+					continue
+				}
+
+				s.record(time.Since(start), hh.Now)
+			case <-s.stopC:
+				ticker.Stop()
+				return
+			}
+		}
+	}()
+
+	return nil
+}
+
+func (p *prober) Remove(id string) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	s, ok := p.targets[id]
+	if !ok {
+		return ErrNotFound
+	}
+	close(s.stopC)
+	delete(p.targets, id)
+	return nil
+}
+
+func (p *prober) RemoveAll() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	for _, s := range p.targets {
+		close(s.stopC)
+	}
+	p.targets = make(map[string]*status)
+}
+
+func (p *prober) Reset(id string) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	s, ok := p.targets[id]
+	if !ok {
+		return ErrNotFound
+	}
+	s.reset()
+	return nil
+}
+
+func (p *prober) Status(id string) (Status, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	s, ok := p.targets[id]
+	if !ok {
+		return nil, ErrNotFound
+	}
+	return s, nil
+}