build: make integration tests run better on macOS and Windows

This changes as many of the integraton tests as possible so that they
use port forwarding rather than the docker IP directly.

Using the docker IP directly does not work on macOS and Windows as the
docker images are running in a VM rather than a container.

This adds the PORTS.md document to document which port numbers we are
using for which service as they need to be unique.

fstest/testserver/testserver.go

@@ -103,14 +103,31 @@ func start(name string) error {
 	}
 	// If we got a _connect value then try to connect to it
 	const maxTries = 30
+	var rdBuf = make([]byte, 1)
 	for i := 1; i <= maxTries; i++ {
-		fs.Debugf(name, "Attempting to connect to %q try %d/%d", connect, i, maxTries)
-		conn, err := net.Dial("tcp", connect)
-		if err == nil {
-			_ = conn.Close()
-			return nil
+		if i != 0 {
+			time.Sleep(time.Second)
 		}
-		time.Sleep(time.Second)
+		fs.Debugf(name, "Attempting to connect to %q try %d/%d", connect, i, maxTries)
+		conn, err := net.DialTimeout("tcp", connect, time.Second)
+		if err != nil {
+			fs.Debugf(name, "Connection to %q failed try %d/%d: %v", connect, i, maxTries, err)
+			continue
+		}
+
+		err = conn.SetReadDeadline(time.Now().Add(time.Second))
+		if err != nil {
+			return fmt.Errorf("failed to set deadline: %w", err)
+		}
+		n, err := conn.Read(rdBuf)
+		_ = conn.Close()
+		fs.Debugf(name, "Read %d, error: %v", n, err)
+		if err != nil && !errors.Is(err, os.ErrDeadlineExceeded) {
+			// Try again
+			continue
+		}
+		//time.Sleep(30 * time.Second)
+		return nil
 	}
 	return fmt.Errorf("failed to connect to %q on %q", name, connect)
 }