From the monthly archives: "December 2010"

ESXi – creating new virtual machines (servers) from the command line

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I was able to get a server up and running at home again, and given what I want to do, using ESXi is a good solution. When it comes to servers I prefer to do: (a) from the command line and (b) using ssh. First thing I did after getting ESXi installed was to enable their “Tech Support Mode“, and then things got interesting. The command line of ESXi 4.1 is limited, but yet powerful enough to do the job nicely.  After some searching I learned how to create a new server on the command line, power it on/off, register it with ESX and destroy it too.

To create and power on a new server I created the following script

#!/bin/sh

## Most of this taken from http://www.vm-help.com/esx40i/manage_without_VI_client_1.php

mkdir $1

# First make the disk
vmkfstools -c 15G -a lsilogic $1/$1.vmdk

# Now output the vmx file
cat < $1/$1.vmx

config.version = "8"
virtualHW.version = "7"
vmci0.present = "TRUE"
displayName = "$1"
floppy0.present = "FALSE"
numvcpus = "2"
scsi0.present = "TRUE"
scsi0.sharedBus = "none"
scsi0.virtualDev = "lsilogic"
memsize = "256"
scsi0:0.present = "TRUE"
scsi0:0.fileName = "$1.vmdk"
scsi0:0.deviceType = "scsi-hardDisk"
ide1:0.present = "TRUE"
ide1:0.fileName = "/vmfs/volumes/datastore1/ISOs/install48-amd64.iso"
ide1:0.deviceType = "cdrom-image"
ethernet0.present = "TRUE"
ethernet0.virtualDev = "vmxnet"
ethernet0.features = "15"
ethernet0.networkName = "VM Network"
ethernet0.addressType = "generated"
ethernet1.present = "TRUE"
ethernet1.virtualDev = "vmxnet"
ethernet1.features = "15"
ethernet1.networkName = "VM Network 2"
ethernet1.addressType = "generated"
guestOS = "freebsd-64"
EOF

# Now register our new VM
vnum=`vim-cmd solo/registervm /vmfs/volumes/datastore1/$1/$1.vmx`
vim-cmd vmsvc/power.on $vnum


#!/bin/sh
vim-cmd vmsvc/power.off `vim-cmd vmsvc/getallvms |grep $1|awk '{print $1}'`
vim-cmd vmsvc/destroy `vim-cmd vmsvc/getallvms |grep $1|awk '{print $1}'`

Then I went ahead and wrote a one liner to create 10 new machines and then destroy them.  Once I get my completely automated OpenBSD installer finished, then I can adjust the creation of the machines to boot from the network.  Thus all I will have to do is run the script to create the machine and then sit back and wait.  In I’m guessing about 15 minutes I’ll have an up and working OpenBSD system.  Since the install will be automated I can also fully customize the final result.  If I was responsible for a group of say web servers and my company just announced some awesome widget that everyone wants, then I had better be prepared to deploy more servers quickly.  Using the above I could easily accomplish that task.  After all if our customers could not use our website then they will not be happy.

To sum up in a single word…. CONSISTENCY

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There is one word that comes to my mind when I think about how to run a data center, consistency! I have worked with many people and organizations over the years. Recently I have seen a fair number of issues and to summarize them with one word I picked consistency.

In my mind this means right or wrong, if you are going to do something be consistent with it. If you’re using jumpstart or kickstart then put the environment in a revision control system, like CVS or Subversion. This way changes can be tracked and logged. Sometimes it is the simplest things that tip me off that say one system out of ten is different.

For example, when I’m deploying applications on many servers at the same time I use cluster ssh. Once connected I’ll ‘sudo su -’ so I can do what I need to do. If some servers have different root prompts then that is an immediate tip to me that the servers are not all the same.

How do you achieve consistency? Automated scripts/tools. When I deploy the applications I don’t do a lot by hand, except for running some scripts that install the various applications.

Now I’m off to continue the fun I’m having today with ESXi and OpenBSD. I’ve figured out how to create hosted servers from the command line, using ssh. Right now I can easily create an OpenBSD virtual server, power it on, and have the install started all using ssh and the ESXi command line. Next up is to create a fully automated OpenBSD install routine. While the installer is simple and easy, it does require someone answer questions. I want a fully automated and customized environment. I did this a few years ago but am now going to re-visit and improve it.