After working on my FC6 AMI I started thinking about how small of an AMI I could create. The goal would be to have a 10 meg or less image that is very specialized for doing something like serving images with lighttpd or apache. I started very very small but the lack of console access on EC2 makes it hard to debug errors so I moved on to try and find a reasonable sized distro that I was more sure would work. I managed to find a Debian image that is pretty small and decided to see if I could make it work for EC2.
While looking around I found this Debian 3.1 Xen image pretty much ready to go. I downloaded it and wrote the following script that can be used to update the image so that it will work as an EC2 AMI.
I assume here that you have downloaded the image from the above site and that the name of the image is still debian.3-1.20061221.img.tar.bz2, if it is not you can modify the script to use the newly named file.
tar xvjf debian.3-1.20061221.img.tar.bz2
rm -f debian.3-1.xen2.cfg
rm -f debian.3-1.xen3.cfg
rm -f debian.swap
mount -o loop debian.3-1.img /mnt
cat <<EOL > /mnt/etc/fstab
/dev/sda1 / ext3 errors=remount-ro 0 1
proc /proc proc defaults 0 0
/dev/sda2 /mnt ext3 errors=remount-ro 0 2
/dev/sda3 none swap sw 0 0
sed -i -e 's/PermitRootLogin no/#PermitRootLogin no/g' /mnt/etc/ssh/sshd_config
cat <<EOL >> /mnt/etc/ssh/sshd_config
cat <<EOL > /mnt/etc/init.d/aws-auth.sh
if [ ! -d /root/.ssh ] ; then
mkdir -p /root/.ssh
chmod 700 /root/.ssh
# or fetch public key using the file in the ephemeral store:
if [ -e /mnt/openssh_id.pub ] ; then
cat /mnt/openssh_id.pub >> /root/.ssh/authorized_keys
chmod 600 /root/.ssh/authorized_keys
chmod +x /mnt/etc/init.d/aws-auth.sh
ln -s ../init.d/aws-auth.sh S41aws-auth
cat <<EOL > /mnt/etc/init.d/firstrun.sh
if [ -f "/.firstrun" ] ; then
dd if=/dev/urandom count=50|md5sum > /tmp/p.out
POUT=\`cat /tmp/p.out | cut -d" " -f1-1\`
rm -f /tmp/p.out
/usr/sbin/usermod -p \$POUT root
rm -f /.firstrun
chmod +x /mnt/etc/init.d/firstrun.sh
ln -s ../init.d/firstrun.sh S39firstrun
After running the script you will have 45 meg image that is ready to run on EC2. Compared to any of the currently available public AMIs this is very small.
I plan on trying to see if I can get an even smaller image before I start creating images for each application I have in mind.