From a313ccb29639e47c4efc003b19d8a6d2d3433a48 Mon Sep 17 00:00:00 2001
From: Matt DeBoer <matt.deboer@gettyimages.com>
Date: Sat, 18 Mar 2017 23:05:42 -0700
Subject: [PATCH] add retries for ExpectedMembers; fail if len(expectedMembers)
 is 0

---
 pkg/cmd/main.go            |  1 +
 pkg/discovery/discovery.go | 39 +++++++++++++++++++++++++-------------
 2 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/pkg/cmd/main.go b/pkg/cmd/main.go
index 2cdcf13..5d7c4ac 100644
--- a/pkg/cmd/main.go
+++ b/pkg/cmd/main.go
@@ -151,5 +151,6 @@ func parseArgs(c *cli.Context) *discovery.Discovery {
 		ProxyMode:            c.Bool("proxy"),
 		IgnoreNamingMismatch: c.Bool("ignore-naming-mismatch"),
 		MasterFilter:         masterFilter,
+		MaxTries:             10,
 	}
 }
diff --git a/pkg/discovery/discovery.go b/pkg/discovery/discovery.go
index e8bbe21..238d51f 100644
--- a/pkg/discovery/discovery.go
+++ b/pkg/discovery/discovery.go
@@ -63,16 +63,26 @@ func (d *Discovery) DiscoverEnvironment() (map[string]string, error) {
 	}
 
 	var expectedMembers []etcd.Member
-	if members, err := p.ExpectedMembers(d.MasterFilter, d.ClientScheme,
-		d.ClientPort, d.ServerScheme, d.ServerPort); err == nil {
-		for _, m := range members {
-			// have to cast here because of golang type-system--ugh!
-			expectedMembers = append(expectedMembers, etcd.Member(m))
+	for tries := 0; tries < d.MaxTries && len(expectedMembers) == 0; tries++ {
+		if members, err := p.ExpectedMembers(d.MasterFilter, d.ClientScheme,
+			d.ClientPort, d.ServerScheme, d.ServerPort); err == nil {
+			for _, m := range members {
+				// have to cast here because of golang type-system--ugh!
+				expectedMembers = append(expectedMembers, etcd.Member(m))
+			}
+		} else {
+			return nil, err
 		}
-	} else {
-		return nil, err
+		sleepTime := (2 * time.Second)
+		if log.GetLevel() >= log.DebugLevel {
+			log.Debugf("Failed to resolve expected members; sleeping for %s", sleepTime)
+		}
+		time.Sleep(sleepTime)
 	}
-	if log.GetLevel() >= log.DebugLevel {
+
+	if len(expectedMembers) == 0 {
+		log.Fatal("Failed to determine expected members")
+	} else if log.GetLevel() >= log.DebugLevel {
 		log.Debugf("Expected cluster members: %v#", expectedMembers)
 	}
 
@@ -160,12 +170,15 @@ func (d *Discovery) DiscoverEnvironment() (map[string]string, error) {
 }
 
 func initialClusterString(members []etcd.Member) string {
-	initialCluster := make([]string, 0, len(members))
-	for _, m := range members {
-		member := fmt.Sprintf("%s=%s", m.Name, m.PeerURLs[0])
-		initialCluster = append(initialCluster, member)
+	if len(members) > 0 {
+		initialCluster := make([]string, 0, len(members))
+		for _, m := range members {
+			member := fmt.Sprintf("%s=%s", m.Name, m.PeerURLs[0])
+			initialCluster = append(initialCluster, member)
+		}
+		return strings.Join(initialCluster, ",")
 	}
-	return strings.Join(initialCluster, ",")
+	return ""
 }
 
 // Check for mismatched names between expected and current members with