Creating an OVA

While working on creating the next version of the pmsApp OVA, I ran into some issues so I thought I would try to make a small guide to creating an OVA here. Mostly for my own benefit.

I installed version 0.2 of the pmsApp and updated it to get the latest software versions. When I then tried to create a new OVA it turned out to be quite a lot larget than the original. I needed to make the image smaller.

I started out by clearing the yum cache and uninstalling the old kernel, that shrinked the used space to around the same as before the update. I found this guide as to how to prepare a VM to be a template, that freed up a bit more space.

Using VirtualBox, i created an OVA from the VM. Now the problem is that an OVA created with VirtualBox can not be imported into ESXi. Fortunately an OVA is actually just a tar archive so I was able to extract the .ovf file and the vmdk’s without issues. After that it is a queston of editing the ovf and changing the hardware version from virtualbox-2.2 to vmx-Y where Y is the vmware hardware version wanted. I plan on going with vmx-8.

Now the problem is assemling the OVA again, to do that, I used vmware’s ovftool, but it wants a .mf file to ensure that the files are not corrupted. I found this article, explaining how to create the .mf file.

To have everything in one place, here is what I have done to the VM to make it into an OVA:

First, we are working “inside” the VM to reduce space used.

Stop logging:

service rsyslog stop
service auditd stop

Remove old kernels:

uname -a
rpm -qa | grep kernel
#remove old kernel versions with. yum remove

Clean yum cache:

yum clean all

Empty logs:

logrotate -f /etc/logrotate.conf
rm –f /var/log/*-???????? /var/log/*.gz /var/log/*.old /var/log/anac*
cat /dev/null > /var/log/audit/audit.log
cat /dev/null > /var/log/wtmp
cat /dev/null > /var/log/lastlog
#there might be other logfiles to empty out with cat /dev/null
#*I will update this next time I go through the process

Clean tmp space:

rm -rf /tmp/*
rm -rf /var/tmp/*

Zero out freespace to ensure disk images can be made as small as possible:

dd if=/dev/zero of=/boot/zerofile bs=1M
rm -rf /boot/zerofile

dd if=/dev/zero of=/zerofile bs=1M
rm +rf /zerofile

Finally shut down the vm:

shutdown -h now

Using VirtualBox, I exported the VM as pmsApp-0.3.ova. Next are the steps taken to ensure that the OVA is as small as possible and can be imported by ESXi.

Extract OVA:

mv pmsApp-0.3.ova pmsApp-0.3.tar
tar xf pmsApp-0.3.tar

Above step can be skipped if the VM is exported as .ovf instead of .ova

Replace the system type to ensure that the OVA can be imported by ESXi:

sed 's/virtualbox-2.2/vmx-8/g' pmsApp-0.3.ovf > pmsApp-tmp.ovf
mv pmsApp-tmp.ovf pmsApp-0.3.ovf

Ensure that the disk image is as small as possible:

qemu-img convert -p -O vmdk pmsApp-0.3-disk1.vmdk thindisk.vmdk
mv thindisk.vmdk pmsApp-0.3-disk1.vmdk

Create a manifest file to ensure data consistency in OVA:

openssl sha1 *.ovf *.vmdk >

Create the OVA:

ovftool pmsApp-0.3.ovf pmsApp-0.3.ova