Fix flaky s3tables tests: allocate all ports atomically

The test port allocation had a TOCTOU race where GetFreePort() would
open a listener, grab the port number, then immediately close it.
When called repeatedly, the OS could recycle a just-released port,
causing two services (e.g. Filer and S3) to be assigned the same port.

Replace per-call GetFreePort() with batch AllocatePorts() that holds
all listeners open until every port is obtained, matching the pattern
already used in test/volume_server/framework/cluster.go.

test/s3tables/lakekeeper/lakekeeper_test.go

@@ -115,10 +115,13 @@ func NewTestEnvironment(t *testing.T) *TestEnvironment {
 
 	bindIP := testutil.FindBindIP()
 
-	masterPort, masterGrpcPort := testutil.MustFreePortPair(t, "Master")
-	volumePort, volumeGrpcPort := testutil.MustFreePortPair(t, "Volume")
-	filerPort, filerGrpcPort := testutil.MustFreePortPair(t, "Filer")
-	s3Port, s3GrpcPort := testutil.MustFreePortPair(t, "S3")
+	// Allocate all ports in a single batch to prevent the OS from recycling
+	// a released port, which can cause two services to get the same port.
+	ports := testutil.MustAllocatePorts(t, 8)
+	masterPort, masterGrpcPort := ports[0], ports[1]
+	volumePort, volumeGrpcPort := ports[2], ports[3]
+	filerPort, filerGrpcPort := ports[4], ports[5]
+	s3Port, s3GrpcPort := ports[6], ports[7]
 
 	return &TestEnvironment{
 		seaweedDir:     seaweedDir,

test/s3tables/polaris/polaris_env_test.go

@@ -89,11 +89,14 @@ func NewTestEnvironment(t *testing.T) *TestEnvironment {
 
 	bindIP := testutil.FindBindIP()
 
-	masterPort, masterGrpcPort := testutil.MustFreePortPair(t, "Master")
-	volumePort, volumeGrpcPort := testutil.MustFreePortPair(t, "Volume")
-	filerPort, filerGrpcPort := testutil.MustFreePortPair(t, "Filer")
-	s3Port, s3GrpcPort := testutil.MustFreePortPair(t, "S3")
-	polarisPort, polarisAdminPort := testutil.MustFreePortPair(t, "Polaris")
+	// Allocate all ports in a single batch to prevent the OS from recycling
+	// a released port, which can cause two services to get the same port.
+	ports := testutil.MustAllocatePorts(t, 10)
+	masterPort, masterGrpcPort := ports[0], ports[1]
+	volumePort, volumeGrpcPort := ports[2], ports[3]
+	filerPort, filerGrpcPort := ports[4], ports[5]
+	s3Port, s3GrpcPort := ports[6], ports[7]
+	polarisPort, polarisAdminPort := ports[8], ports[9]
 
 	return &TestEnvironment{
 		seaweedDir:       seaweedDir,

test/s3tables/sts_integration/sts_integration_test.go

@@ -93,10 +93,13 @@ func NewTestEnvironment(t *testing.T) *TestEnvironment {
 
 	bindIP := testutil.FindBindIP()
 
-	masterPort, masterGrpcPort := testutil.MustFreePortPair(t, "Master")
-	volumePort, volumeGrpcPort := testutil.MustFreePortPair(t, "Volume")
-	filerPort, filerGrpcPort := testutil.MustFreePortPair(t, "Filer")
-	s3Port, s3GrpcPort := testutil.MustFreePortPair(t, "S3") // Changed to use testutil.MustFreePortPair
+	// Allocate all ports in a single batch to prevent the OS from recycling
+	// a released port, which can cause two services to get the same port.
+	ports := testutil.MustAllocatePorts(t, 8)
+	masterPort, masterGrpcPort := ports[0], ports[1]
+	volumePort, volumeGrpcPort := ports[2], ports[3]
+	filerPort, filerGrpcPort := ports[4], ports[5]
+	s3Port, s3GrpcPort := ports[6], ports[7]
 
 	return &TestEnvironment{
 		seaweedDir:      seaweedDir,

test/s3tables/testutil/docker.go

@@ -15,33 +15,44 @@ func HasDocker() bool {
 	return cmd.Run() == nil
 }
 
+// MustFreePortPair is a convenience wrapper for tests that only need a single pair.
+// Prefer MustAllocatePorts when allocating multiple pairs to guarantee uniqueness.
 func MustFreePortPair(t *testing.T, name string) (int, int) {
-	httpPort, grpcPort, err := findAvailablePortPair()
-	if err != nil {
-		t.Fatalf("Failed to get free port pair for %s: %v", name, err)
-	}
-	return httpPort, grpcPort
+	ports := MustAllocatePorts(t, 2)
+	return ports[0], ports[1]
 }
 
-func findAvailablePortPair() (int, int, error) {
-	httpPort, err := GetFreePort()
-	if err != nil {
-		return 0, 0, err
-	}
-	grpcPort, err := GetFreePort()
+// MustAllocatePorts allocates count unique free ports atomically.
+// All listeners are held open until every port is obtained, preventing
+// the OS from recycling a port between successive allocations.
+func MustAllocatePorts(t *testing.T, count int) []int {
+	t.Helper()
+	ports, err := AllocatePorts(count)
 	if err != nil {
-		return 0, 0, err
+		t.Fatalf("Failed to allocate %d free ports: %v", count, err)
 	}
-	return httpPort, grpcPort, nil
+	return ports
 }
 
-func GetFreePort() (int, error) {
-	listener, err := net.Listen("tcp", "0.0.0.0:0")
-	if err != nil {
-		return 0, err
+// AllocatePorts allocates count unique free ports atomically.
+func AllocatePorts(count int) ([]int, error) {
+	listeners := make([]net.Listener, 0, count)
+	ports := make([]int, 0, count)
+	for i := 0; i < count; i++ {
+		l, err := net.Listen("tcp", "0.0.0.0:0")
+		if err != nil {
+			for _, ll := range listeners {
+				_ = ll.Close()
+			}
+			return nil, err
+		}
+		listeners = append(listeners, l)
+		ports = append(ports, l.Addr().(*net.TCPAddr).Port)
+	}
+	for _, l := range listeners {
+		_ = l.Close()
 	}
-	defer listener.Close()
-	return listener.Addr().(*net.TCPAddr).Port, nil
+	return ports, nil
 }
 
 func WaitForService(url string, timeout time.Duration) bool {