Monday, March 18, 2013

Installing ruby 2.0 on Ubuntu 12.04

I wanted to find a way to install ruby 2.0 on Ubuntu 12.04 via Chef, without going the rvm route, which is harder to automate. After several tries, I finally found a list of .deb packages which are necessary and sufficient as pre-requisites. Writing it down here for my future reference, and maybe it will prove useful to others out there.

I downloaded most of these packages from packages.ubuntu.com (if you google their names you'll find them), then I installed them via 'dpkg -i'. Here they are:


libffi5_3.0.9-1_amd64.deb
libssl0.9.8_0.9.8o-7ubuntu3.1_amd64.deb
zlib1g-dev_1.2.3.4.dfsg-3ubuntu4_amd64.deb

The actual ruby .deb package was built with fpm by my colleague Jeff Roberts courtesy of this blog post.




Wednesday, March 06, 2013

No snowflakes allowed

"Snowflake" is a term I learned from my colleague Jeff Roberts. It is used in the Chef community (maybe in the configuration management community at large as well) to designate a server/node that is 'unique', i.e. not in configuration management control. In a Chef environment, it means that the node in question was never added to Chef and never had chef-client run on it.

We've all been in situations where it seems overkill to go through the effort of automating the setup of a server. Maybe the server has a unique purpose within our infrastructure. Maybe we didn't feel like spending the time to create Chef recipes for that server. Whatever the reasoning, it seemed low-risk at the time.

Well, I am here to tell you there is danger in this way of thinking. Example: we deployed a server in EC2 manually. We installed the Sensu client on it manually and pointed it at our Sensu server. Everything seemed fine. Then one day we updated our Sensu configuration (via Chef) both on the Sensu server and on all the Sensu clients. Of course, the Sensu configuration on our snowflake server never got updated, since chef-client wasn't running on that server. As a result, the Sensu client wasn't checking in properly with the Sensu server, and the snowflake behaved as if it was falling off the map as far as our monitoring system was concerned. We had to manually update Sensu on the snowflake to bring it in sync with our configuration changes.

Basically, the result of having snowflake servers is that they do fall off the map as far as the overall automation of your infrastructure is concerned. They suffer bitrot, and you end up spending lots of time on their care and feeding, thus defeating the purpose of saving the time to automate them in the first place.

This being said, it's hard to be disciplined enough to run chef-client periodically on every single server in your infrastructure. I've never been able to do that before, but we are doing it now, mostly because of the insistence of Jeff. I do see the advantages of this discipline, and I do recommend it to everybody.

Tuesday, March 05, 2013

Video and slides for 'Five years of EC2 distilled' talk

On February 19th I gave a talk at the Silicon Valley Cloud Computing Meetup about my experiences and lessons learned while using EC2 for the past 5 years or so. I posted the slides on Slideshare and there's also a video recording of my presentation. I think the talk went pretty well, judging by the many questions I got at the end. Hopefully it will be useful to some people out there who are wondering if EC2 or The Cloud in general is a good fit for their infrastructure (short answer: it very much depends).

I want to thank Sebastian Stadil from Scalr for inviting me to give the talk (he first contacted me about giving a talk like this in -- believe it or not -- early 2008!). I also want to thank Adobe for hosting the meeting, and CDNetworks for sponsoring the meeting.