Fallback to non-loopback IF addresses for Domain IPs (#6918)

When MINIO_PUBLIC_IPS is not specified and no endpoints are passed
as arguments, fallback to the address of non loop-back interfaces.

This is useful so users can avoid setting MINIO_PUBLIC_IPS in docker
or orchestration scripts, ince users naturally setup an internal
network that connects all instances.

cmd/common-main.go

@@ -221,14 +221,18 @@ func handleCommonEnvVars() {
 	minioEndpointsEnv, ok := os.LookupEnv("MINIO_PUBLIC_IPS")
 	if ok {
 		minioEndpoints := strings.Split(minioEndpointsEnv, ",")
-		globalDomainIPs = set.NewStringSet()
 		for i, ip := range minioEndpoints {
 			if net.ParseIP(ip) == nil {
 				logger.FatalIf(errInvalidArgument, "Unable to initialize Minio server with invalid MINIO_PUBLIC_IPS[%d]: %s", i, ip)
 			}
-			globalDomainIPs.Add(ip)
 		}
+		updateDomainIPs(set.CreateStringSet(minioEndpoints...))
+	} else {
+		// Add found interfaces IP address to global domain IPS,
+		// loopback addresses will be naturally dropped.
+		updateDomainIPs(localIP4)
 	}
+
 	if globalDomainName != "" && !globalDomainIPs.IsEmpty() && globalEtcdClient != nil {
 		var err error
 		globalDNSConfig, err = dns.NewCoreDNS(globalDomainName, globalDomainIPs, globalMinioPort, globalEtcdClient)

cmd/endpoint.go

@@ -455,7 +455,12 @@ func CreateEndpoints(serverAddr string, args ...[]string) (string, EndpointList,
 		return serverAddr, endpoints, setupType, err
 	}
 
-	updateDomainIPs(uniqueArgs)
+	_, dok := os.LookupEnv("MINIO_DOMAIN")
+	_, eok := os.LookupEnv("MINIO_ETCD_ENDPOINTS")
+	_, iok := os.LookupEnv("MINIO_PUBLIC_IPS")
+	if dok && eok && !iok {
+		updateDomainIPs(uniqueArgs)
+	}
 
 	setupType = DistXLSetupType
 	return serverAddr, endpoints, setupType, nil
@@ -509,21 +514,21 @@ func GetRemotePeers(endpoints EndpointList) []string {
 	return peerSet.ToSlice()
 }
 
-// In federated and distributed setup, update IP addresses of the hosts passed in command line
-// if MINIO_PUBLIC_IPS are not set manually
 func updateDomainIPs(endPoints set.StringSet) {
-	_, dok := os.LookupEnv("MINIO_DOMAIN")
+	ipList := set.NewStringSet()
-	_, eok := os.LookupEnv("MINIO_ETCD_ENDPOINTS")
+	for e := range endPoints {
-	_, iok := os.LookupEnv("MINIO_PUBLIC_IPS")
+		host, _, err := net.SplitHostPort(e)
-	if dok && eok && !iok {
+		if err != nil {
-		globalDomainIPs = set.NewStringSet()
+			if strings.Contains(err.Error(), "missing port in address") {
-		for e := range endPoints {
+				host = e
-			host, _, _ := net.SplitHostPort(e)
+			} else {
-			ipList, _ := getHostIP4(host)
+				continue
-			remoteIPList := ipList.FuncMatch(func(ip string, matchString string) bool {
+			}
-				return !strings.HasPrefix(ip, "127.")
-			}, "")
-			globalDomainIPs.Add(remoteIPList.ToSlice()[0])
 		}
+		IPs, _ := getHostIP4(host)
+		ipList = ipList.Union(IPs)
 	}
+	globalDomainIPs = ipList.FuncMatch(func(ip string, matchString string) bool {
+		return !strings.HasPrefix(ip, "127.")
+	}, "")
 }