embed: use machine default host only for default value, 0.0.0.0

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

embed/config.go

@@ -57,20 +57,12 @@ var (
 	DefaultInitialAdvertisePeerURLs = "http://localhost:2380"
 	DefaultAdvertiseClientURLs      = "http://localhost:2379"
 
-	defaultHostname   string = "localhost"
+	defaultHostname   string
 	defaultHostStatus error
 )
 
 func init() {
-	ip, err := netutil.GetDefaultHost()
-	if err != nil {
-		defaultHostStatus = err
-		return
-	}
-	// found default host, advertise on it
-	DefaultInitialAdvertisePeerURLs = "http://" + net.JoinHostPort(ip, "2380")
-	DefaultAdvertiseClientURLs = "http://" + net.JoinHostPort(ip, "2379")
-	defaultHostname = ip
+	defaultHostname, defaultHostStatus = netutil.GetDefaultHost()
 }
 
 // Config holds the arguments for configuring an etcd server.
@@ -358,34 +350,49 @@ func (cfg Config) InitialClusterFromName(name string) (ret string) {
 func (cfg Config) IsNewCluster() bool { return cfg.ClusterState == ClusterStateFlagNew }
 func (cfg Config) ElectionTicks() int { return int(cfg.ElectionMs / cfg.TickMs) }
 
-// IsDefaultHost returns the default hostname, if used, and the error, if any,
-// from getting the machine's default host.
-func (cfg Config) IsDefaultHost() (string, error) {
-	if len(cfg.APUrls) == 1 && cfg.APUrls[0].String() == DefaultInitialAdvertisePeerURLs {
-		return defaultHostname, defaultHostStatus
-	}
-	if len(cfg.ACUrls) == 1 && cfg.ACUrls[0].String() == DefaultAdvertiseClientURLs {
-		return defaultHostname, defaultHostStatus
-	}
-	return "", defaultHostStatus
+func (cfg Config) defaultPeerHost() bool {
+	return len(cfg.APUrls) == 1 && cfg.APUrls[0].String() == DefaultInitialAdvertisePeerURLs
 }
 
-// UpdateDefaultClusterFromName updates cluster advertise URLs with default host.
+func (cfg Config) defaultClientHost() bool {
+	return len(cfg.ACUrls) == 1 && cfg.ACUrls[0].String() == DefaultAdvertiseClientURLs
+}
+
+// UpdateDefaultClusterFromName updates cluster advertise URLs with, if available, default host,
+// if advertise URLs are default values(localhost:2379,2380) AND if listen URL is 0.0.0.0.
+// e.g. advertise peer URL localhost:2380 or listen peer URL 0.0.0.0:2380
+// then the advertise peer host would be updated with machine's default host,
+// while keeping the listen URL's port.
+// User can work around this by explicitly setting URL with 127.0.0.1.
+// It returns the default hostname, if used, and the error, if any, from getting the machine's default host.
 // TODO: check whether fields are set instead of whether fields have default value
-func (cfg *Config) UpdateDefaultClusterFromName(defaultInitialCluster string) {
-	defaultHost, defaultHostErr := cfg.IsDefaultHost()
-	defaultHostOverride := defaultHost == "" || defaultHostErr == nil
-	if (defaultHostOverride || cfg.Name != DefaultName) && cfg.InitialCluster == defaultInitialCluster {
-		cfg.InitialCluster = cfg.InitialClusterFromName(cfg.Name)
-		ip, _, _ := net.SplitHostPort(cfg.LCUrls[0].Host)
-		// if client-listen-url is 0.0.0.0, just use detected default host
-		// otherwise, rewrite advertise-client-url with localhost
-		if ip != "0.0.0.0" {
-			_, acPort, _ := net.SplitHostPort(cfg.ACUrls[0].Host)
-			cfg.ACUrls[0] = url.URL{Scheme: cfg.ACUrls[0].Scheme, Host: fmt.Sprintf("localhost:%s", acPort)}
+func (cfg *Config) UpdateDefaultClusterFromName(defaultInitialCluster string) (string, error) {
+	if defaultHostname == "" || defaultHostStatus != nil {
+		if cfg.Name != DefaultName && cfg.InitialCluster == defaultInitialCluster {
 			cfg.InitialCluster = cfg.InitialClusterFromName(cfg.Name)
 		}
+		return "", defaultHostStatus
+	}
+
+	used := false
+	pip, pport, _ := net.SplitHostPort(cfg.LPUrls[0].Host)
+	if cfg.defaultPeerHost() && pip == "0.0.0.0" {
+		cfg.APUrls[0] = url.URL{Scheme: cfg.APUrls[0].Scheme, Host: fmt.Sprintf("%s:%s", defaultHostname, pport)}
+		used = true
+		if cfg.Name != DefaultName && cfg.InitialCluster == defaultInitialCluster {
+			cfg.InitialCluster = cfg.InitialClusterFromName(cfg.Name)
+		}
+	}
+
+	cip, cport, _ := net.SplitHostPort(cfg.LCUrls[0].Host)
+	if cfg.defaultClientHost() && cip == "0.0.0.0" {
+		cfg.ACUrls[0] = url.URL{Scheme: cfg.ACUrls[0].Scheme, Host: fmt.Sprintf("%s:%s", defaultHostname, cport)}
+		used = true
+	}
+	if !used {
+		defaultHostname = ""
 	}
+	return defaultHostname, defaultHostStatus
 }
 
 // checkBindURLs returns an error if any URL uses a domain name.