12.11. Importing Amazon Machine Images

The following procedures describe how to import an Amazon Machine Image (AMI) into CloudStack when using the XenServer hypervisor.

Assume you have an AMI file and this file is called CentOS_6.2_x64. Assume further that you are working on a CentOS host. If the AMI is a Fedora image, you need to be working on a Fedora host initially.

You need to have a XenServer host with a file-based storage repository (either a local ext3 SR or an NFS SR) to convert to a VHD once the image file has been customized on the Centos/Fedora host.

Note

When copying and pasting a command, be sure the command has pasted as a single line before executing. Some document viewers may introduce unwanted line breaks in copied text.

Set up loopback on image file:

# mkdir -p /mnt/loop/centos62
# mount -o loop  CentOS_6.2_x64 /mnt/loop/centos54

Install the kernel-xen package into the image. This downloads the PV kernel and ramdisk to the image.
```
# yum -c /mnt/loop/centos54/etc/yum.conf --installroot=/mnt/loop/centos62/ -y install kernel-xen
```

Create a grub entry in /boot/grub/grub.conf.

# mkdir -p /mnt/loop/centos62/boot/grub
# touch /mnt/loop/centos62/boot/grub/grub.conf
# echo "" > /mnt/loop/centos62/boot/grub/grub.conf

Determine the name of the PV kernel that has been installed into the image.

# cd /mnt/loop/centos62
# ls lib/modules/
2.6.16.33-xenU  2.6.16-xenU  2.6.18-164.15.1.el5xen  2.6.18-164.6.1.el5.centos.plus  2.6.18-xenU-ec2-v1.0  2.6.21.7-2.fc8xen  2.6.31-302-ec2
# ls boot/initrd*
boot/initrd-2.6.18-164.6.1.el5.centos.plus.img boot/initrd-2.6.18-164.15.1.el5xen.img
# ls boot/vmlinuz*
boot/vmlinuz-2.6.18-164.15.1.el5xen  boot/vmlinuz-2.6.18-164.6.1.el5.centos.plus  boot/vmlinuz-2.6.18-xenU-ec2-v1.0  boot/vmlinuz-2.6.21-2952.fc8xen

Xen kernels/ramdisk always end with "xen". For the kernel version you choose, there has to be an entry for that version under lib/modules, there has to be an initrd and vmlinuz corresponding to that. Above, the only kernel that satisfies this condition is 2.6.18-164.15.1.el5xen.

Based on your findings, create an entry in the grub.conf file. Below is an example entry.

default=0
timeout=5
hiddenmenu
title CentOS (2.6.18-164.15.1.el5xen)
        root (hd0,0)
        kernel /boot/vmlinuz-2.6.18-164.15.1.el5xen ro root=/dev/xvda 
        initrd /boot/initrd-2.6.18-164.15.1.el5xen.img

Edit etc/fstab, changing “sda1” to “xvda” and changing “sdb” to “xvdb”.

# cat etc/fstab
/dev/xvda  /         ext3    defaults        1 1
/dev/xvdb  /mnt      ext3    defaults        0 0
none       /dev/pts  devpts  gid=5,mode=620  0 0
none       /proc     proc    defaults        0 0
none       /sys      sysfs   defaults        0 0

Enable login via the console. The default console device in a XenServer system is xvc0. Ensure that etc/inittab and etc/securetty have the following lines respectively:
```
# grep xvc0 etc/inittab 
co:2345:respawn:/sbin/agetty xvc0 9600 vt100-nav
# grep xvc0 etc/securetty 
xvc0
```

Ensure the ramdisk supports PV disk and PV network. Customize this for the kernel version you have determined above.

# chroot /mnt/loop/centos54
# cd /boot/
# mv initrd-2.6.18-164.15.1.el5xen.img initrd-2.6.18-164.15.1.el5xen.img.bak
# mkinitrd -f /boot/initrd-2.6.18-164.15.1.el5xen.img --with=xennet --preload=xenblk --omit-scsi-modules 2.6.18-164.15.1.el5xen

Change the password.

# passwd
Changing password for user root.
New UNIX password: 
Retype new UNIX password: 
passwd: all authentication tokens updated successfully.

Exit out of chroot.
```
# exit
```

Check etc/ssh/sshd_config for lines allowing ssh login using a password.

# egrep "PermitRootLogin|PasswordAuthentication" /mnt/loop/centos54/etc/ssh/sshd_config  
PermitRootLogin yes
PasswordAuthentication yes

If you need the template to be enabled to reset passwords from the CloudStack UI or API, install the password change script into the image at this point. See Section 12.13, “Adding Password Management to Your Templates”.

Unmount and delete loopback mount.

# umount /mnt/loop/centos54
# losetup -d /dev/loop0

Copy the image file to your XenServer host's file-based storage repository. In the example below, the Xenserver is "xenhost". This XenServer has an NFS repository whose uuid is a9c5b8c8-536b-a193-a6dc-51af3e5ff799.
```
# scp CentOS_6.2_x64 xenhost:/var/run/sr-mount/a9c5b8c8-536b-a193-a6dc-51af3e5ff799/
```

[root@xenhost ~]# cd /var/run/sr-mount/a9c5b8c8-536b-a193-a6dc-51af3e5ff799
[root@xenhost a9c5b8c8-536b-a193-a6dc-51af3e5ff799]#  ls -lh CentOS_6.2_x64
-rw-r--r-- 1 root root 10G Mar 16 16:49 CentOS_6.2_x64
[root@xenhost a9c5b8c8-536b-a193-a6dc-51af3e5ff799]# xe vdi-create virtual-size=10GiB sr-uuid=a9c5b8c8-536b-a193-a6dc-51af3e5ff799 type=user name-label="Centos 6.2 x86_64"
cad7317c-258b-4ef7-b207-cdf0283a7923

Import the image file into the VDI. This may take 10–20 minutes.

[root@xenhost a9c5b8c8-536b-a193-a6dc-51af3e5ff799]# xe vdi-import filename=CentOS_6.2_x64 uuid=cad7317c-258b-4ef7-b207-cdf0283a7923

Locate a the VHD file. This is the file with the VDI’s UUID as its name. Compress it and upload it to your web server.

[root@xenhost a9c5b8c8-536b-a193-a6dc-51af3e5ff799]# bzip2 -c cad7317c-258b-4ef7-b207-cdf0283a7923.vhd > CentOS_6.2_x64.vhd.bz2
[root@xenhost a9c5b8c8-536b-a193-a6dc-51af3e5ff799]# scp CentOS_6.2_x64.vhd.bz2 webserver:/var/www/html/templates/