Configuration Management Series Part 2 of 3: Chef

Be sure to read the follow up to this article as well!

Back when I was looking at configuration management about 4 years ago, I explored the possibility of using Chef over Puppet. A few things threw me off at that point in time: the heavy reliance on Ruby for the setup and configuration (at least via the main documented methods), the myth that you needed to know Ruby to work with it, and ultimately, time: the ramp-up time to get started seemed so long that it was actually time prohibitive for me at a period in my life where I had very little to spare. A couple of years later, when it came to pick one to work with, I ultimately chose Puppet.

Over the years, I have heard talk every now and then about use of configuration management tools. It saddened me to hear not so much talk about Puppet, but interestingly, a lot of developers that I spoke with really like Chef, and there’s no doubt that some consider it an essential part of their toolbox. Read on, and you will probably see why.

About Chef

Chef seems to have come about as a matter of necessity, and ultimately was the manifestation of the end result of DevOps – infrastructure automation. Creator Adam Jacob probably tells it way better than I could in this video, where he explains the name, his journey in making the software, and OpsCode’s beginnings.

What I actually got from the video was the dispelling of a misconception I had – that Chef actually came from former employees of Puppet that wanted to create something better. If that was the case, it may have just been a natural evolution of the philosophies that Puppet was built on, and how Adam and company thought they could make it better to suit OpsCode’s needs.

Installation

I’m not going to lie – this was probably the most frustrating part of my teardown on Sunday.

Installation is pretty straightforward. Actually, very straightforward now, as opposed to when it tried it out so many years ago. The server install documentation now gives a much better path to installation, versus how it used to be when it involved gems and what not.

Unfortunately, the base install of Chef server is extremely resource intensive. The installer package for the server on Ubuntu is about 460 MB in size, which takes sizeable amount of time to download and install. You need about 2 GB of RAM to run the whole stack – after installation the total footprint is a little over 1 GB in RAM. I actually had to rebuild my test instance after the initial install with 512 MB failed.

From here, what to do next was a little confusing for me. This ultimately is due to the very modular nature of the Chef management lifecycle – which is great for developers (see below), but is a bit intimidating for first-time admin users or people looking to stand up with little time and minimal knowledge – only having a Sunday afternoon for review is a great example of this.

Ultimately, I pushed through and figured it out. The full path to getting a node up is basically:

This will get you set up with the server, a workstation to do your work, and a node to test with. What this does not do, apparently, is get chef-client to run on boot on the bootstrapped node. I’m not too sure why this is, but the installer package does not include any init scripts, unfortunately. With me being overdue for press time as it is, I chose not to investigate for now, and just ran chef-client manually to test the cookbook that I wrote.

Windows Support

Chef has pretty mature Windows support. Actually, one of the reasons that I chose Puppet over Chef in the first place was that Puppet’s Windows support was further along. I would imagine both are in the same place now.

Chef has also been working on support for PowerShell DSC, MS’s own approach to configuration management through PowerShell.

Head over to the Windows page to see the full feature set for Chef on Windows.

Manageability

Chef takes a very modular approach to management. Ideally, one has the server, and changes are made from workstations thru knife, save possibly organization creation and user management. This includes cookbook design, cookbook uploading, node bootstrapping, run list editing (the list of items that get run on a node during a run), and pretty much everything else about the Chef development lifecycle.

Again, hosts are bootstrapped usually via knife bootstrap – but there are other deployment options as well. See the bootstrap page for more options.

Data storage for nodes is done thru data bags – JSON-formatted data with support for encryption, similar to Hiera and hiera-eyaml for Puppet. I haven’t had much of a chance to look yet, but it looks like the features to not only automate this process and have encrypted and unencrypted data co-exist within the same data bag is a lot more automated and developer-friendly, probably better than Puppet and much better than Ansible.

Finally, there are the premium features. Check the Chef server page for more details. These features include a web interface, extra support for push jobs, analytics, and high availability. It should be noted that these features are free for up to 25 nodes.

Execution Model

Some more time needs to be taken by myself to evaluate all of these methods, but generally, chef-client is your go-to for all execution. Take a look at the run model here. This can be run as a daemon, periodically thru cron, direct on the server, or via knife ssh.

Speaking of which, there is also knife, where most of your Chef management needs will be taken care of thru.

There is also chef-solo – basically, a standalone Chef that does not require a server to be run. This kind of supplies an agentless push-execution model for Chef that can be useful for orchestration.

Programmability

Chef really is a developer’s dream come true.

The Chef DK installation model encourages a developer-centric development and deployment cycle, allowing all management and development to be done from a single developer’s workstation, with changes checked into central source control.

The DSL is pretty much pure Ruby. When Chef first started to become a thing, this was yet another excuse thrown out to not use it – ie: you would need to learn Ruby to learn Chef. But really, nearly all configuration management systems these days use some sort of language for their DSL, be it Ruby, YAML, JSON, or whatever. I would even submit that one can begin teaching themselves a specific language by taking up a configuration management system – learning Puppet actually helped me understand Ruby and ERB a bit. In addition to that, Chef has a great doc that can help you out – Just Enough Ruby for Chef.

Templating is done in ERB, just like in Puppet. See the template documentation for more details.

Terminology and actual concepts are more in line with Puppet. Cookbooks are pretty much the analog to modules or classes in Puppet, with recipes translating to individual manifests (the run data). You can use knife cookbook to create, verify, and upload cookbooks.

Speaking of development – this is actually a functional recipe:

file '/etc/motd' do
  content 'hello world!'
end

Set up within a cookbook – this would write “hello world!” to /etc/motd. Pretty simple!

I think the killer app for development for me here though has to be the testing support that Chef has built in:

  • kitchen is Chef’s built-in test suite that allows you to orchestrate a test scenario from scratch using a wide range or virtualization technologies (including Vagrant – so you don’t even need to have code leave your workstation)!
  • learn.chef.io is a great resource for learning Chef, versus testing Chef. It is a hosted training platform that will set up temporary instances for you to use, along with a guided tutorial.

For me, when people say that Chef is more developer-friendly – it’s not necessarily what you can do or what you can use, but the fact that the toolset enables developers to get code out all that faster.

Conclusion

Great for developers

Chef is awesome for developers, and it shows. The Ruby DSL is extremely easy to work with – that fact that they have made it more programmatic than other configuration management systems would seem to allow it to do more without having to extend it too much or look to third parties for extensions. Also, the Chef DK and Kitchen provide for a very pleasant development experience.

A little tough to get ramped up on

If you are in a pinch and don’t have a lot of time to set up and do not know Chef, you might want to figure something else out until you can block a bit of time to teach yourself. There are a lot of options for you to use Chef, which can make it overwhelming. Setting up the Chef server as well is a bit of a commitment of resources that you may want to consider carefully before you undertake it.

Next up in the series – an oldie but a goodie, the tool that got me started down the configuration management rabbit hole – Puppet.

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