Cloud-init Supports CloudStack As Data Source

Cloud-init is a set of init scripts for cloud instances. Cloud instances need special scripts to run during initialization to retrieve and install ssh keys and to let the user run various scripts. EC2 users might already be familiar with this tool as its pre-configured on most Linux distributions available on the AWS marketplace.

CloudStack users instead have relied on 2 scripts, cloudstack-set-guest-password and cloudstack-set-guest-sshkey, for setting SSH and admin password for instances running on the CloudStack IaaS platform. While these scripts do the job, they are shell scripts running as individual services and do only a single function. Adding more functionality would mean creating additional standalone scripts with lots of code duplication.

Cloud-init on the other hand is a Python framework and already has a long list of modules that can re-size the filesystem, update hostname, add apt repositories and even trigger chef/puppet runs. Wouldn’t it be nice to use cloud-init on Cloudstack IaaS platform also. Just like on EC2!!!

Thanks to Cosmin Luta, Cloud-init 0.6.3 onwards can now fetch instance meta-data from the CloudStack Virtual Router. Since new features/modules are being added to Cloud-init all the time, it’s best to use the latest releases. CentOS/RHEL users can get updated RPMS from repos.fedorapeople.org

To use cloud-init on CentOS/RHEL 6.x,

1. Add the EPEL repo

   $ rpm -ivh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
   Retrieving http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
   Preparing...                ########################################### [100%]
      1:epel-release           ########################################### [100%]
   

2. Add the cloud-init repo at http://repos.fedorapeople.org/repos/openstack/cloud-init/epel-6/

   [epel-cloud-init]
   name=CloudInit-$releasever
   baseurl=http://repos.fedorapeople.org/repos/openstack/cloud-init/epel-$releasever/
   enabled=1
   gpgcheck=1
   

3. Install cloud-init

   $ yum install cloud-init
   Loaded plugins: fastestmirror
   Loading mirror speeds from cached hostfile
    * base: mirror.leapswitch.com
    * epel: epel.mirror.net.in
    * extras: mirror.leapswitch.com
    * updates: mirror.leapswitch.com
   Setting up Install Process
   Resolving Dependencies
   --> Running transaction check
   ---> Package cloud-init.noarch 0:0.7.2-2.el6 will be installed
   --> Finished Dependency Resolution
   
   Dependencies Resolved
   
   =========================================================
    Package      Arch   Version       Repository   Size
   =========================================================
   Installing:
    cloud-init   noarch 0.7.2-2.el6    init        412 k
   
   Transaction Summary
   =========================================================
   Install       1 Package(s)
   
   Total download size: 412 k
   Installed size: 1.3 M
   Is this ok [y/N]: y
   Downloading Packages:
   cloud-init-0.7.2-2.el6.noarch.rpm  | 412 kB     00:02     
   Running rpm_check_debug
   Running Transaction Test
   Transaction Test Succeeded
   Running Transaction
   Warning: RPMDB altered outside of yum.
     Installing : cloud-init-0.7.2-2.el6.noarch 1/1 
     Verifying  : cloud-init-0.7.2-2.el6.noarch 1/1 
   
   Installed:
     cloud-init.noarch 0:0.7.2-2.el6
   
   Complete!
   $ rpm -qi cloud-init
   Name        : cloud-init                   Relocations: (not relocatable)
   Version     : 0.7.2                             Vendor: Red Hat, Inc.
   Release     : 2.el6                         Build Date: Wed 26 Jun 2013 05:37:52 AM EDT
   Install Date: Mon 28 Oct 2013 06:12:47 AM EDT      Build Host: ppc-012.build.bos.redhat.com
   Group       : System Environment/Base       Source RPM: cloud-init-0.7.2-2.el6.src.rpm
   Size        : 1414362                          License: GPLv3
   Signature   : (none)
   Packager    : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
   URL         : http://launchpad.net/cloud-init
   Summary     : Cloud instance init scripts
   Description :
   Cloud-init is a set of init scripts for cloud instances.  Cloud instances
   need special scripts to run during initialization to retrieve and install
   ssh keys and to let the user run various scripts.
   
   

4. Add datasource_list: [‘CloudStack’] to the top of /etc/cloud/cloud.cfg. If you fail to set the correct data source, cloud-init will default to using 169.254.169.254 as the meta-data source IP instead of the Virtual Router.

   datasource_list: ['CloudStack']
   

5. Verify the rest of cloud.cfg defaults before rebooting. WARNING: The defaults will disable password login for SSH (ssh_pwauth: 0)

So can Cloud-init replace cloud-set-guest scripts?

Cloud-init was able to set the SSH key correctly on my CentOS 6.4 test instance environment (blog post coming soon) so it should be possible to deprecate cloudstack-guest-set-sshkey script atleast.

Will be testing the cloudstack-guest-set-password functionality also soon. It would also be nice if the “resizefs” was able to resize the data disk now that CloudStack provide an API for resizing volumes

Shanker Balan

Shanker Balan is a devops and infrastructure freelancer with over 14 years of industry experience in large scale Internet systems. He is available for both short term and long term projects on contract. Please use the Contact Form for any enquiry.

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