Here are some tricks I use to make my vagrant boxes as small as possible:

Tips:

Booting in single user mode:

I boot in single user mode since it will prevent running services that could output logs. I do this because I zero out all my logs before packaging the box.

Updating:

After updating any package, run yum clean (or the apt equivalent).

When booted in single user mode, don’t forget to start-up your network before updating.

When updating kernels, install the kernel packages, reboot and remove the old kernel packages that are no longer in use. Remember to re-install the VirtualBox add-ons too after a kernel update.

Cleanup:

After doing whatever you need to do with the box, I do some rather nasty stuff to make sure the box uses as little as possible place. If you are using a RAW hard-disks, these might be a bad idea (stuff gets BIG).

• Zero out all remaining unused disk space
• Zero out the swap
• Clear out all log files (I just make them empty, I do NOT delete them)

Script:

(You can find this script – or an older version in /root/tools/cleanup_diskspace.sh on my newer vagrant boxes.)

cat - << EOWARNING
WARNING: This script will fil up your left over disk space.
 
DO NOT RUN THIS WHEN YOUR VIRTUAL HD IS RAW!!!!!!
 
You should NOT do this on a running system.
This is purely for making vagrant boxes damn small.
 
Press Ctrl+C within the next 10 seconds if you want to abort!!
 
EOWARNING
sleep 10;
 
echo 'Cleanup bash history'
unset HISTFILE
[ -f /root/.bash_history ] && rm /root/.bash_history
[ -f /home/vagrant/.bash_history ] && rm /home/vagrant/.bash_history
 
echo 'Cleanup log files'
find /var/log -type f | while read f; do echo -ne '' > $f; done;
 
echo 'Whiteout root'
count=`df --sync -kP / | tail -n1  | awk -F ' ' '{print $4}'`; 
let count--
dd if=/dev/zero of=/tmp/whitespace bs=1024 count=$count;
rm /tmp/whitespace;
 
echo 'Whiteout /boot'
count=`df --sync -kP /boot | tail -n1 | awk -F ' ' '{print $4}'`;
let count--
dd if=/dev/zero of=/boot/whitespace bs=1024 count=$count;
rm /boot/whitespace;
 
swappart=`cat /proc/swaps | tail -n1 | awk -F ' ' '{print $1}'`
swapoff $swappart;
dd if=/dev/zero of=$swappart;
mkswap $swappart;
swapon $swappart;

Furthermore – about this script – USE IT AT YOUR OWN RISK