discovery: print out detailed cluster error

Author: xiang90

client/cluster_error.go

@@ -14,10 +14,20 @@
 
 package client
 
+import "fmt"
+
 type ClusterError struct {
 	Errors []error
 }
 
 func (ce *ClusterError) Error() string {
 	return ErrClusterUnavailable.Error()
 }
+
+func (ce *ClusterError) Detail() string {
+	s := ""
+	for i, e := range ce.Errors {
+		s += fmt.Sprintf("error #%d: %s\n", i, e)
+	}
+	return s
+}

discovery/discovery.go

@@ -221,7 +221,8 @@ func (d *discovery) checkCluster() ([]*client.Node, int, uint64, error) {
 		if err == client.ErrInvalidJSON {
 			return nil, 0, 0, ErrBadDiscoveryEndpoint
 		}
-		if _, ok := err.(*client.ClusterError); ok {
+		if ce, ok := err.(*client.ClusterError); ok {
+			plog.Error(ce.Detail())
 			return d.checkClusterRetry()
 		}
 		return nil, 0, 0, err
@@ -235,7 +236,8 @@ func (d *discovery) checkCluster() ([]*client.Node, int, uint64, error) {
 	resp, err = d.c.Get(ctx, d.cluster, nil)
 	cancel()
 	if err != nil {
-		if _, ok := err.(*client.ClusterError); ok {
+		if ce, ok := err.(*client.ClusterError); ok {
+			plog.Error(ce.Detail())
 			return d.checkClusterRetry()
 		}
 		return nil, 0, 0, err
@@ -266,7 +268,7 @@ func (d *discovery) checkCluster() ([]*client.Node, int, uint64, error) {
 func (d *discovery) logAndBackoffForRetry(step string) {
 	d.retries++
 	retryTime := time.Second * (0x1 << d.retries)
-	plog.Infof("%s: connection to %s timed out, retrying in %s", step, d.url, retryTime)
+	plog.Infof("%s: error connecting to %s, retrying in %s", step, d.url, retryTime)
 	d.clock.Sleep(retryTime)
 }
 
@@ -311,7 +313,8 @@ func (d *discovery) waitNodes(nodes []*client.Node, size int, index uint64) ([]*
 		plog.Noticef("found %d peer(s), waiting for %d more", len(all), size-len(all))
 		resp, err := w.Next(context.Background())
 		if err != nil {
-			if _, ok := err.(*client.ClusterError); ok {
+			if ce, ok := err.(*client.ClusterError); ok {
+				plog.Error(ce.Detail())
 				return d.waitNodesRetry()
 			}
 			return nil, err