Building an AMI: Difference between revisions
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Created page with '= Create a Loopback File = A Loopback file is a file that will contain the contents of an Operating System. You can think of it like a VMDK file as located in a vmWare instance....' |
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#!/bin/bash | #!/bin/bash | ||
IMG="CentOS53_Vanilla.img" | IMG="CentOS53_Vanilla.img" # Image File Name | ||
Size=2" # Image File Size in GB | |||
dd if=/dev/zero of=$IMG bs=1G count= | dd if=/dev/zero of=$IMG bs=1G count=$Size | ||
mke2fs -F -j $IMG | mke2fs -F -j $IMG | ||
Revision as of 02:54, 29 May 2009
Create a Loopback File
A Loopback file is a file that will contain the contents of an Operating System. You can think of it like a VMDK file as located in a vmWare instance.
dd if=/dev/zero of=CentOS53_Vanilla.img bs=1M count=1024
The paramaters are as:
- bs, block size. 1M = 1 MB, 1G = 1GB.
- count, how many blocks.
- of, the name of the image file
Example
| ======== | ============ | ======== | ================== |
| bs | count | size | caculation |
| ======== | ============ | ======== | ================== |
| bs=1M | count=1024 | 1GB | 1MB * 1024 = 1GB |
| bs=1M | count=2048 | 2GB | 1MB * 2048 = 2GB |
| bs=1M | count=5120 | 5GB | 1MB * 5120 = 5GB |
| bs=1G | count=10 | 10GB | 1GB * 10 = 10GB |
| ======== | ============ | ======== | ================== |
Create root File System
mke2fs -F -j CentOS53_Vanilla.img
Mounting the Image File
mkdir /tmp/image_file mount -o loop CentOS53_Vanilla.img /tmp/image_file
Prepare for Installation
Ignore the errors in the output
mkdir /tmp/image_file/dev MAKEDEV -d /tmp/image_file/dev -x console MAKEDEV -d /tmp/image_file/dev -x null MAKEDEV -d /tmp/image_file/dev -x zero
Create the fstab File
Add the following to the file /etc/fstab
First create folder and file.
mkdir /tmp/image_file/etc touch /tmp/image_file/etc/fstab
Now copy the contents below into the newly create file.
/dev/sda1 / ext3 defaults 1 1 /dev/sda2 /mnt ext3 defaults 0 0 /dev/sda3 swap swap defaults 0 0 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
proc
Create and then mount proc folder.
mkdir /tmp/image_file/proc mount -t proc none /tmp/image_file/proc
Ignore any outpout messages.
MAKEDEV -d /tmp/image_file/dev -x console MAKEDEV -d /tmp/image_file/dev -x null MAKEDEV -d /tmp/image_file/dev -x zero
Install OS
yum -c /etc/yum.repos.d/CentOS-Base.repo --installroot=/tmp/image_file -y groupinstall Base
NOTE: You will need to edit or make a copy of the CentOS-Base.repo and make sure that you remove or remark out the mirrorlist and use baseurl. You will also need to change $releasever to the version that you would like to load.
Configure OS
Add the following contents to the file:
/tmp/image_file/etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0 BOOTPROTO=dhcp ONBOOT=yes TYPE=Ethernet USERCTL=yes PEERDNS=yes IPV6INIT=no <pre> = Un-Mount Image = Now that the OS is installed and configured we can now unmount the image. <pre> umount /tmp/image_file/proc umount -d /tmp/image_file rmdir /tmp/image_file
Automated Script
#!/bin/bash IMG="CentOS53_Vanilla.img" # Image File Name Size=2" # Image File Size in GB dd if=/dev/zero of=$IMG bs=1G count=$Size mke2fs -F -j $IMG mkdir /tmp/image_file mount -o loop $IMG /tmp/image_file mkdir /tmp/image_file/dev MAKEDEV -d /tmp/image_file/dev -x console MAKEDEV -d /tmp/image_file/dev -x null MAKEDEV -d /tmp/image_file/dev -x zero mkdir /tmp/image_file/etc echo "/dev/sda1 / ext3 defaults 1 1" > /tmp/image_file/etc/fstab echo "/dev/sda2 /mnt ext3 defaults 0 0" >> /tmp/image_file/etc/fstab echo "/dev/sda3 swap swap defaults 0 0" >> /tmp/image_file/etc/fstab echo "none /dev/ pts devpts gid=5,mode=620 0 0" >> /tmp/image_file/etc/fstab echo "none /dev/ shm tmpfs defaults 0 0" >> /tmp/image_file/etc/fstab echo "none /proc proc defaults 0 0" >> /tmp/image_file/etc/fstab echo "none /sys sysfs defaults 0 0" >> /tmp/image_file/etc/fstab mkdir /tmp/image_file/proc mount -t proc none /tmp/image_file/proc MAKEDEV -d /tmp/image_file/dev -x console MAKEDEV -d /tmp/image_file/dev -x null MAKEDEV -d /tmp/image_file/dev -x zero yum -c /etc/yum.repos.d/CentOS-Base.repo --installroot=/tmp/image_file -y groupinstall Base echo "DEVICE=eth0" > /tmp/image_file/etc/sysconfig/network-scripts/ifcfg-eth0 echo "BOOTPROTO=dhcp" >> /tmp/image_file/etc/sysconfig/network-scripts/ifcfg-eth0 echo "ONBOOT=yes" >> /tmp/image_file/etc/sysconfig/network-scripts/ifcfg-eth0 echo "TYPE=Ethernet" >> /tmp/image_file/etc/sysconfig/network-scripts/ifcfg-eth0 echo "USERCTL=yes" >> /tmp/image_file/etc/sysconfig/network-scripts/ifcfg-eth0 echo "PEERDNS=yes" >> /tmp/image_file/etc/sysconfig/network-scripts/ifcfg-eth0 echo "IPV6INIT=no" >> /tmp/image_file/etc/sysconfig/network-scripts/ifcfg-eth0 umount /tmp/image_file/proc umount -d /tmp/image_file rmdir /tmp/image_file
