Prepare CentOS image for OpenStack Image Service

Please also refer to here

Download CentOS install ISO file from http://wiki.centos.org/Download

Verify that the libvirt "default" network is active

In my case, it is not active

# virsh net-list
Name                 State      Autostart     Persistent
--------------------------------------------------

libvirt has an example default network XML file under /usr/share/libvirt/networks

# cat /usr/share/libvirt/networks/default.xml
<network>
  <name>default</name>
  <bridge name="virbr0" />
  <forward/>
  <ip address="192.168.122.1" netmask="255.255.255.0">
    <dhcp>
      <range start="192.168.122.2" end="192.168.122.254" />
    </dhcp>
  </ip>
</network>

According to http://wiki.libvirt.org/page/Networking , we can use the following steps to create "default" network :

# virsh net-define /usr/share/libvirt/networks/default.xml
Network default defined from /usr/share/libvirt/networks/default.xml

After running the above command, the following file is created :

# ls -al /etc/libvirt/qemu/networks/default.xml
-rw-------. 1 root root 579 Jun 19 22:51 /etc/libvirt/qemu/networks/default.xml
[root@novo networks]# cat default.xml
<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made using:
  virsh net-edit default
or other application using the libvirt API.
-->

<network>
  <name>default</name>
  <uuid>a459e540-d37d-cfb4-99ad-1c846144ac0d</uuid>
  <forward mode='nat'/>
  <bridge name='virbr0' stp='on' delay='0' />
  <mac address='52:54:00:28:C3:B5'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254' />
    </dhcp>
  </ip>
</network>
# virsh net-start default
Network default started

# brctl show
bridge name    bridge id        STP enabled    interfaces
pan0        8000.000000000000    no       
qbr24110dfe-84        8000.f21061f22ed8    no        qvb24110dfe-84
                            tap24110dfe-84
qbr426f579f-55        8000.d6804b3332d3    no        qvb426f579f-55
                            tap426f579f-55
virbr0        8000.52540028c3b5    yes        virbr0-nic

virbr0 is the bridge for default network

Now default network is active

# virsh net-list
Name                 State      Autostart     Persistent
--------------------------------------------------
default              active     no            yes


# qemu-img create -f qcow2 /tmp/centos-6.5.qcow2 10G
Formatting '/tmp/centos-6.5.qcow2', fmt=qcow2 size=10737418240 encryption=off cluster_size=65536


# virt-install --virt-type kvm --name centos-6.5 --ram 1024 --cdrom=/tmp/CentOS-6.5-x86_64-netinstall.iso --disk /tmp/centos-6.5.qcow2,format=qcow2 --network network=default --graphics vnc,listen=0.0.0.0 --noautoconsole --os-type=linux --os-variant=rhel6

Starting install...
Creating domain...                                                                                |    0 B     00:00    
Domain installation still in progress. You can reconnect to
the console to complete the installation process.

Now continue installation on virt-manager

* select IPv4 DHCP
* select URL

Hostname : localhost.localdomain

* select basic server

After installation is done, reject CDROM by running

# virsh attach-disk --type cdrom --mode readonly centos-6.5 "" hdc
Disk attached successfully

# virsh dumpxml centos-6.5 (before and after diff )

<     <disk type='file' device='cdrom'>
---
>     <disk type='block' device='cdrom'>
32,33c32
<       <source file='/tmp/CentOS-6.5-x86_64-netinstall.iso'/>
<       <target dev='hdc' bus='ide'/>
---
>       <target dev='hdc' bus='ide' tray='open'/>

Now restart

# virsh destroy centos-6.5
Domain centos-6.5 destroyed

# virsh start centos-6.5
Domain centos-6.5 started

The cloud-init package will automatically fetch the public key from the metadata server and place the key in an account. We continue to install the package.

After server is back, login into the server as root.

 # rpm -Uvh http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
Retrieving http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
warning: /var/tmp/rpm-tmp.ih3yas: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY
Preparing...                ########################################### [100%]
   1:epel-release           ########################################### [100%]


# yum install cloud-init

After installed, vi /etc/cloud/cloud.cfg

remove the following lines :

default_user:
    name: cloud-user

Instead, add the following lines : (centos user will be created when OpenStack starts this image, we do not have to create this user manually)

  default_user:
    name: centos
    lock_passwd: true
    gecos: Centos Cloud User
    groups: [wheel, adm]
    sudo: ["ALL=(ALL) NOPASSWD:ALL"]
    shell: /bin/bash

Disable the zeroconf route

In order for the instance to access the metadata service, disable the default zeroconf route:

# echo "NOZEROCONF=yes" >> /etc/sysconfig/network

Configure console

vi /boot/grub/grub.conf

add console=ttyS0,115200n8 to the line that begins with kernel


    kernel /vmlinuz-2.6.32-431.el6.x86_64 ro 
root=/dev/mapper/VolGroup-lv_root rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD rd_LVM_LV=VolGroup/lv_swap SYSFONT=latar
cyrheb-sun16 crashkernel=auto rd_LVM_LV=VolGroup/lv_root  KEYBOARDTYPE=pc KEYTABLE=us 
console=ttyS0,115200n8 rd_NO_DM rhgb quiet

Shutdown the instance

# /sbin/shutdown -h now

Clean up

There is a utility called virt-sysprep, that performs various cleanup tasks such as removing the MAC address references. It will clean up a virtual machine image in place

# virt-sysprep -d centos-6.5
Examining the guest ...
Performing "yum-uuid" ...
Performing "utmp" ...
Performing "udev-persistent-net" ...
Performing "sssd-db-log" ...
Performing "ssh-userdir" ...
Performing "ssh-hostkeys" ...
Performing "smolt-uuid" ...
Performing "script" ...
Performing "samba-db-log" ...
Performing "rpm-db" ...
Performing "rhn-systemid" ...
Performing "random-seed" ...
Performing "puppet-data-log" ...
Performing "pam-data" ...
Performing "package-manager-cache" ...
Performing "pacct-log" ...
Performing "net-hwaddr" ...
Performing "net-hostname" ...
Performing "mail-spool" ...
Performing "machine-id" ...
Performing "logfiles" ...
Performing "hostname" ...
Performing "firstboot" ...
Performing "dovecot-data" ...
Performing "dhcp-server-state" ...
Performing "dhcp-client-state" ...
Performing "cron-spool" ...
Performing "crash-data" ...
Performing "blkid-tab" ...
Performing "bash-history" ...
Performing "abrt-data" ...
Performing "lvm-uuids" ...

 # virsh undefine centos-6.5
Domain centos-6.5 has been undefined

Now /tmp/centos-6.5.qcow2 is ready for uploading to the OpenStack Image Service.

After this image is uploaded to OpenStack and then we can start an instance.

Now try to connect to this instance.

$ ssh centos@172.24.4.232
The authenticity of host '172.24.4.232 (172.24.4.232)' can't be established.
RSA key fingerprint is b5:4a:5c:c8:9e:e9:63:19:65:b0:80:6c:ab:be:20:08.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '172.24.4.232' (RSA) to the list of known hosts.
[centos@centos-test01 ~]$