Creating an AMI through a Loopback File

To mount the file through loopback

1. Create a mount point in the file system where the image will be attached:

   # mkdir <image_mountpoint>

   where <image_mountpoint> is the location where the image will be mounted.

2. Mount the file system image:

   # mount -o loop  <image_name> <image_mountpoint>

   where <image_name> is the name of the image file and <image_mountpoint> is the mount location.

To prepare for the installation

1. Create a /dev directory and populate it with a minimal set of devices (you can ignore the errors in the output):

   # mkdir /mnt/ec2-fs/dev
   # /sbin/MAKEDEV -d <image_mountpoint>/dev -x console
   # /sbin/MAKEDEV -d <image_mountpoint>/dev -x null
   # /sbin/MAKEDEV -d <image_mountpoint>/dev -x zero

   where <image_mountpoint> is the mount location.

2. Create the fstab file within the /etc directory and add the following:

   /dev/sda1  /         ext3    defaults        1 1
   none       /dev/pts  devpts  gid=5,mode=620  0 0
   none       /dev/shm  tmpfs   defaults        0 0
   none       /proc     proc    defaults        0 0
   none       /sys      sysfs   defaults        0 0

3. Create a temporary yum configuration file (e.g., yum-xen.conf) and add the following components:

   [main]
   cachedir=/var/cache/yum
   debuglevel=2
   logfile=/var/log/yum.log
   exclude=*-debuginfo
   gpgcheck=0
   obsoletes=1
   reposdir=/dev/null
   
   [base]
   name=Fedora Core 4 - $basearch - Base
   mirrorlist=http://fedora.redhat.com/download/mirrors/fedora-core-$releasever
   enabled=1
   
   [updates-released]
   name=Fedora Core 4 - $basearch - Released Updates
   mirrorlist=http://fedora.redhat.com/download/mirrors/updates-released-fc$releasever
   enabled=1

   This ensures all the required basic packages and utilities are installed. This file can be located anywhere on your main file system (not on your loopback file system) and is only used during installation.

4. Enter the following:

   # mkdir <image_mountpoint>/proc
   # mount -t proc none <image_mountpoint>/proc

   where <image_mountpoint> is the mount location. A groupadd utility bug in the shadow-utils package (versions prior to 4.0.7-7) requires you to mount the new proc file system manually with the above command.

To configure the operating system

1. Edit (or create) /mnt/ec2-fs/etc/sysconfig/network-scripts/ifcfg-eth0 and make sure it contains at least the following information:

   DEVICE=eth0
   BOOTPROTO=dhcp
   ONBOOT=yes
   TYPE=Ethernet
   USERCTL=yes
   PEERDNS=yes
   IPV6INIT=no

   	Note
   	The Amazon EC2 DHCP server ignores hostname requests. If you set DHCP_HOSTNAME, the local hostname will be set on the instance but not externally. Additionally, the local hostname will be the same for all instances of the AMI, which might be confusing.

2. Ensure that networking starts by making sure the following line appears in the /mnt/ec2-fs/etc/sysconfig/network file:

   NETWORKING=yes

3. Amazon EC2 provides the instance with additional local disk storage on /dev/sda2 and swap space on /dev/sda3. To ensure both these are mounted at system startup, add the following lines to /mnt/ec2-fs/etc/fstab:

   /dev/sda2  /mnt      ext3    defaults        0 0
   /dev/sda3  swap      swap    defaults        0 0

   	Note
   	The /dev/sda2 and /dev/sda3 storage locations only apply to small instances. For more information on instance storage, see the section called “Instance Storage” .

4. Make sure all of your required services start at system startup by allocating them appropriate system run levels. For example, to enable the service my-service on multi-user and networked run levels, enter the following commands:

   # chroot /mnt/ec2-fs /bin/sh
   # chkconfig --level 345 my-service on
   # exit 

5. After your new installation is successfully installed and configured to operate in the Amazon EC2 environment, you can unmount the image:

   # umount <image_mountpoint>/proc
   # umount -d <image_mountpoint> 

   where <image_mountpoint> is the mount location.