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Replies:
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Last Post:
Apr 17, 2007 7:21 PM
by: awsdevel
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Posts:
5,320
Registered:
3/19/07
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CentOS-5 AMI?
Posted:
Apr 17, 2007 8:36 AM PDT
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Is anyone working on an AMI based on the new CentOS-5 release?
Does anyone have any thoughts on the potential compatibility of CentOS-5 with EC2, or the relative merits of using CentOS-5 vs. other distributions?
Thanks.
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Posts:
644
Registered:
3/24/06
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Re: CentOS-5 AMI?
Posted:
Apr 17, 2007 12:03 PM PDT
in response to: Allen
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We expect to have a nice base image public this week.
Thorsten - www.rightscale.com
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Posts:
12
Registered:
2/5/07
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Re: CentOS-5 AMI?
Posted:
Apr 17, 2007 7:21 PM PDT
in response to: Allen
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We are working on a build process for a CentOS 5 AMI, somewhat similar to the EC2 documentation tutorial on building a loopback FC4 image. Here are the points to consider when choosing one over the other:
1) CentOS 5 is 99.9% Red Hat Enterprise Linux 5. With exception to the yum update process used within CentOS, the only difference between the two is the name. In fact, with CentOS5/RHEL5, yum is the actual update process under the hood - up2date is now just a simple wrapper around yum.
2) RHEL/CentOS is a cathedral development process. The focus is on reliability and stability, with few anticipated changes between minor releases. The core of RHEL/CentOS is actually Fedora, but with substantial work put into fault tolerance and reliability.
3) FC6 maps to RHEL5, FYI. The technology developed within the Fedora Core project are eventually migrated over to the Red Hat Enterprise Linux product, after being thoroughly tested and vetted for problems.
4) Fedora Core, on the other hand, is a bazaar development process. The focus is to release early and often, with almost daily changes to the core OS and associated packages. It is not uncommon to see 100 packages required to update an FC box just a month after a major release.
So, if you want to run Fedora Core on EC2, you will have to keep constant watch on the daily updates required to keep in sync with the main project. The Fedora Core team has not fully worked out the demarcation point between security updates and regular system updates, so it's usually best to just update everything on an FC box to insure there are no issues with dependencies. Within the architecture of EC2, that means your AMI instance will update several times per week, but unless you rebundle everything back to S3 after each update, if you lose an instance you will have to launch an AMI then do a full package update, or use a manual build process to insure you are using the most recent packages. If you launch an FC4/6 AMI without having the most recent packages installed, you run the risk of getting compromised if that AMI is pointed towards the Internet. More importantly, if you do a system wide upgrade on an FC box and it breaks something, you might not be able to contact the AMI and you will lose all of the data stored on it. If you opt for FC, it is wise to go with the groupinstall Core option as opposed to groupinstall Base, as that will bring your package count down to 100 or so, and the AMI won't be constantly thrashing with each yum update cycle.
If you want to run CentOS/RHEL, you will have few updates to worry about, and very stable performance. The downside is that the most recent versions of packages aren't going to be available for CentOS/RHEL. If you require the most bleeding edge version of Rails there is a good chance it's not going to be in the standard yum repo for CentOS/RHEL, and unless you do the build yourself and you are committed to keeping those packages up to date manually, you'll have to wait until the next minor release for today's set of packages to carry over.
So the answer is, it depends on your application. For a standard Apache/Postgresql/PHP server, no question - go with CentOS5/RHEL5. For something more advanced, like lighttpd with Rails, maybe FC is the better alternative.
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