Invalid Virtual Machine

Today I tried to add a VMware VM created by a VMware workstation to my VMware Server 2 on Windows, but failed because it was considered to be invalid. VMware server told me "either the vmx file is corrupted or the VM was created using a newer version of VMware product." Seems both were not the case.

However, it turns out the vmx file could really be "corrupted". In vmx, the first line is

.encoding = "windows-1252"

After change it to be

.encoding = "UTF-8"

The VM is no longer considered to be invalid.

Then after I changed the "numvcpus" from 2 to 1, the VM is able to run on my VMware server, which unfortunately only has one single core CPU.

But interestingly, the original VM can run on a VMware server 2 on Linux.

I also need to change VM's network to be NAT instead of Bridged, and restart VM, to enable networking.

The guideline is that the virtual hardware for a particular Guest OS, such as the number of CPUs and the network type, has to be compatible with the hardware spec of the VMware server installation. For instance, you can not run a 2-CPU VM on a VMware server supporting only one CPU; and if there is no DHCP on the bridged network, then not surprisingly the VM can not acquire an IP if using the bridged network.

Make a Java-enabled Virtual Machine Using Ubuntu JeOS

As suggested in the best practice to build a virtual appliance by VMware, Ubuntu JeOS is used as the operating system. In around 100MB, it provides a just enough OS. After installed, its VMware virtual disk file size is about 380MB.

By default, Ubuntu does not provide a root password. The root privilege is carried out using the "sudo" command. To enable root login: sudo passwd root.

Also, see how to prepare a virtual appliance from the Ubuntu community.

Adding a new virtual disk

• To add a new virtual disk, using the "Add Hardware" command in VMware web interface.
• Need to restart the virtual machine to detect the new virtual disk.
• Let's say the newly added hard drive is /dev/sdb. Use the following command to partition it: fdisk /dev/sdb. To create a single new partition, the entire size of /dev/sdb: n ENTER p ENTER 1 ENTER (default) ENTER (default) ENTER w ENTER.
• To format it: mkfs.ext3 /dev/sdb.
• To mount it on an existing location, say /data: mount /dev/sdb /data.
  

See how to format a new hard disk on ubuntu forums.

Making a Java appliance

The next step will be to make it a Java appliance, with JDK, ant as well as Tomcat installed, running some Java application like Grimoires.

Ubuntu JeOS does not pre-install Open SSH server. Use the following command to install Open SSH: apt-get install openssh-server.

Then install

• JDK 1.6.0_10
  
• Apache Ant 1.7.1
• Apache Tomcat 5.5.27
• Grimoires 2.0.0

The used disk space shown by "df" inside virtual machine is about 675MB.

Setting up NAT

Assume the virtual machine has been configured to support NAT. Add the following line to /etc/vmware/vmnet8/nat/nat.conf, under the [incomingtcp] section:

6660 = 172.16.59.132:8080

where 172.16.59.132 is the IP address of the virtual machine.

According to the VMware server user guide, clicking "Refresh Network List" in the Virtual Infrastructure web interface should bring up the modified network configuration. But it does not work in my case. I have to restart VMware to enforce the new NAT configuration: service vmware restart. (Better shut down vm before restart vmware server!)

After restart VMware, and make sure the port 6660 is opened in the firewall of the host machine, access http://hostname_of_the_host:6660/grimoires from another machine.

It seems that vmware server runs a separate daemon to handle the address translation when vm is set to use NAT. So this blocks iptables' NAT configuration.

Cloning the Virtual Machine

This is something a little bit tricky.

I used the conventional way to clone it: copy the vmdk and vmx files; then add the clone virtual machine to the inventory ("Add Virtual Machine to Inventory"); when asked whether you copied it or moved it, answer copied it.

The clone was able to start up. But there was no eth0. The routing table was empty (shown by route). There was an eth1 with the correct MAC address but without IP information (shown by ifconfig). Not surprisingly, TCP/IP was not working.

My judgement was that there was no reason for the virtual network card to go wrong, so it should be due to some configuration issue.

Hinted by a post about adding a second network card to Ubuntu, I used dmesg | grep eth to check the kernel messages on booting. Then I found an interesting message: "udev: rename eth0 to eth1". After a little bit googling and investigation, I solved the problem!

udev is the device manager for the Linux 2.6 kernel series. In /etc/udev/rules.d/70-persistent-net.rules, there were two lines:
SUBSYSTEM=="net", ...... ATTR{address}=="00:0c:29:07:6f:37", ...... NAME="eth0"
SUBSYSTEM=="net", ...... ATTR{address}=="00:0c:29:cf:c8:64", ...... NAME="eth1"

The MAC address in the first line is the one of the original vm, while the MAC address in the second line is the correct MAC address of the clone. Clearly, the first line has no effect, because there is no such a device in the system. And the second line adds the network card as eth1.

Looking at /etc/network/interfaces, it only defines lo and eth0. eth0 is defined like this:
auto eth0
iface eth0 inet dhcp

There is no wonder why only eth1 was visible but did not support TCP/IP. After commenting out the first line and changing eth1 to eth0 in the second line in /etc/udev/rules.d/70-persistent-net.rules, and restarting the system, TCP/IP is working!

Summary

This is a convenient way to prepare a small footprint Virtual Machine for running Java. It can be used to deliver Java software, or as a test or evaluation environment for Java product.

Use Virtual Machine to Evaluate Software

Here at OMII-UK we need to evaluate software generated in the commissioned software project from time to time. For instance, now it is my duty to evaluate SPAM-GP, some JSR-168 portlets for security stuff. I am using VMware Server to do this job. I think it is great! Basically, I build a virtual machine, in which I install, configure and test the software to be evaluated. Benefits by doing so are obvious:

• It is a VM, where the software is running. So it has all advantages as we dedicate a physical machine to the software. This is a working instance, and we can keep it as long as we wish. It is also easy for someone else who wants to see a demo or to play with it.
• Compared to a physical machine, the VM only costs around 3GB disk space. Sounds quite large, but it is little in my 200GB harddisk.

VMware Server supports snapshot. A snapshot is a persistent state of the whole VM. It can be used to save the current state of the VM, which we are happy with. Then we can carry on manipulating the VM and come back to the snapshot whenever we want. But unfortunately, in VMware Server, only one snapshot can be taken for each VM. A newly taken snapshot will simply replace the previous one.

My machine has 1GB memory. So sometimes it is slow to run VMware server, particularly when two VMs are running at the same time.