Merge pull request #4919 from hashicorp/fix4798

builder/vmware: make vnc probe timeout configurable

builder/vmware/iso/driver_esx5.go

@@ -198,6 +198,16 @@ func (d *ESX5Driver) VNCAddress(_ string, portMin, portMax uint) (string, uint,
 		}
 	}
 
+	vncTimeout := time.Duration(15)
+	envTimeout := os.Getenv("PACKER_ESXI_VNC_PROBE_TIMEOUT")
+	if envTimeout != "" {
+		if parsedTimeout, err := time.ParseDuration(envTimeout); err != nil {
+			log.Printf("Error parsing PACKER_ESXI_VNC_PROBE_TIMEOUT. Falling back to default (15s). %s", err)
+		} else {
+			vncTimeout = parsedTimeout
+		}
+	}
+
 	for port := portMin; port <= portMax; port++ {
 		if _, ok := listenPorts[fmt.Sprintf("%d", port)]; ok {
 			log.Printf("Port %d in use", port)
@@ -205,7 +215,7 @@ func (d *ESX5Driver) VNCAddress(_ string, portMin, portMax uint) (string, uint,
 		}
 		address := fmt.Sprintf("%s:%d", d.Host, port)
 		log.Printf("Trying address: %s...", address)
-		l, err := net.DialTimeout("tcp", address, 30*time.Second)
+		l, err := net.DialTimeout("tcp", address, vncTimeout)
 
 		if err != nil {
 			if e, ok := err.(*net.OpError); ok {

website/source/docs/builders/vmware-iso.html.md

@@ -482,6 +482,21 @@ modify as well:
     format of the exported virtual machine. This defaults to "ovf".
     Before using this option, you need to install `ovftool`.
 
+
+### VNC port discovery
+
+Packer needs to decide on a port to use for VNC when building remotely. To find
+an open port, we try to connect to ports in the range of `vnc_port_min` to
+`vnc_port_max`. If we notice something is listening on a port in the range, we
+try to connect to the next one, and so on until we find a port that has nothing
+listening on it. If you have many clients building on the ESXi host, there
+might be competition for the VNC ports. You can adjust how long packer waits
+for a connection timeout by setting `PACKER_ESXI_VNC_PROBE_TIMEOUT`. This
+defaults to 15 seconds. Set this shorter if vnc connections are refused, and
+set it longer if Packer can't find an open port. This is intended as an
+advanced configuration option. Please make sure your firewall settings are
+correct before adjusting.
+
 ### Using a Floppy for Linux kickstart file or preseed
 
 Depending on your network configuration, it may be difficult to use packer's