etcdserver: clear error on DNS resolution fail on advertise URLs

Signed-off-by: Gyuho Lee <[email protected]>

etcdserver/config.go

@@ -156,9 +156,16 @@ func (c *ServerConfig) advertiseMatchesCluster() error {
 			missing = append(missing, url)
 		}
 	}
-	mstr := strings.Join(missing, ",")
+	if len(missing) > 0 {
+		mstr := strings.Join(missing, ",")
+		umap := types.URLsMap(map[string]types.URLs{c.Name: c.PeerURLs})
+		return fmt.Errorf("--initial-advertise-peer-urls has %s but missing from --initial-cluster=%s", mstr, umap.String())
+	}
+
+	// resolved URLs from "--initial-advertise-peer-urls" and "--initial-cluster" did not match or failed
+	apStr := strings.Join(apurls, ",")
 	umap := types.URLsMap(map[string]types.URLs{c.Name: c.PeerURLs})
-	return fmt.Errorf("--initial-advertise-peer-urls has %s but missing from --initial-cluster=%s", mstr, umap.String())
+	return fmt.Errorf("failed to resolve %s to match --initial-cluster=%s", apStr, umap.String())
 }
 
 func (c *ServerConfig) MemberDir() string { return filepath.Join(c.DataDir, "member") }