Fail gateway properly with an error on port conflicts (#6303)

cmd/gateway-main.go

@@ -22,7 +22,6 @@ import (
 	"net/url"
 	"os"
 	"os/signal"
-	"runtime"
 	"strings"
 	"syscall"
 
@@ -83,17 +82,6 @@ func ValidateGatewayArguments(serverAddr, endpointAddr string) error {
 		return err
 	}
 
-	if runtime.GOOS == "darwin" {
-		_, port := mustSplitHostPort(serverAddr)
-		// On macOS, if a process already listens on LOCALIPADDR:PORT, net.Listen() falls back
-		// to IPv6 address i.e minio will start listening on IPv6 address whereas another
-		// (non-)minio process is listening on IPv4 of given port.
-		// To avoid this error situation we check for port availability only for macOS.
-		if err := checkPortAvailability(port); err != nil {
-			return err
-		}
-	}
-
 	if endpointAddr != "" {
 		// Reject the endpoint if it points to the gateway handler itself.
 		sameTarget, err := sameLocalAddrs(endpointAddr, serverAddr)
@@ -148,6 +136,12 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 	// Handle common env vars.
 	handleCommonEnvVars()
 
+	// On macOS, if a process already listens on LOCALIPADDR:PORT, net.Listen() falls back
+	// to IPv6 address ie minio will start listening on IPv6 address whereas another
+	// (non-)minio process is listening on IPv4 of given port.
+	// To avoid this error situation we check for port availability.
+	logger.FatalIf(checkPortAvailability(globalMinioPort), "Unable to start the server")
+
 	// Validate if we have access, secret set through environment.
 	if !globalIsEnvCreds {
 		logger.Fatal(uiErrEnvCredentialsMissingGateway(nil), "Unable to start gateway")

cmd/http/listen_nix.go

@@ -21,7 +21,6 @@ package http
 import "github.com/valyala/tcplisten"
 
 var cfg = &tcplisten.Config{
-	ReusePort:   true,
 	DeferAccept: true,
 	FastOpen:    true,
 }