Thursday, April 29, 2010

Adventures with chef-server and Gentoo, part 2

Followup to part 1

Once I had a chef-server and webui all set up on my dev box, the next part is to create a "stem cell" image that has chef loaded up on there. Chef 0.8 uses SSL for its new validation mechanism, and so the server creates public/private keypairs for the validation. These are encapsulated in a Chef concept called a client. It took me a while to figure out that client was not a good choice of words. It might have been better renamed as access or credentials.

To begin, I needed to set up knife in the environment I intended to do chef development on. In this case, I appropriated the VM running chef-server but this is not necessary. In fact, I intend to have a dedicated chef-dev VM running in the near future. However, I don't want to run the script I had setup to provision another Gentoo image from storage. I'd still have to change the hostname, run emerge --sync, get the packages up to date, clone my vim setup ... many of the things I intend for chef to handle. Ideally, I'd add a node with roles[dev] and it would just eventually give me back a VM with my dev environment set up.

Setting up knife works like this:

$ sudo knife configure --initial
Your chef server URL? http://chef-server:4000
Your client user name? hosh
Your validation client user name? chef-validator
Path to a chef repository (or leave blank)? .
WARN: *****
WARN: You must place your client key in:
WARN: /home/hhh/.chef/hosh.pem
WARN: Before running commands with Knife!
WARN: *****
WARN: You must place your validation key in:
WARN: /home/hhh/.chef/chef-validator.pem
WARN: Before generating instance data with Knife!
WARN: *****
WARN: Configuration file written to /hosh/hhh/.chef/knife.rb

I have chef-server added in my /etc/hosts file using the private IP address. With that, I can get knife cookbooks list. They were mostly empty, which is what I expected. The weird thing was seeing how I had to copy over validation.pem over. I mean, that's a private key. I don't want it floating around, even if this was all on my private VM cloud on my box. The process I'm working through now will eventually make its way to production. I wasn't so sure about this idea with dropping that validation.pem private key, but for now, I took it on faith until I know this system better and I can re-examine the assumptions again.

Now, I provisioned another vm, did the emerge --sync, pulled down the chef-overlay, unmasked the chef-client packages, installed chef-client, started it up ... and nothing. It was not appearing in my node list.

The reason was because the node did not have the authentication key. I flailed around on several online documentation. I came across the documentation that says that, clients are how you create the access, and that while they are conventionally tied to a node, it is not necessary. Since I was making a template image that, ideally, on the first boot, it would phone home and register itself, I figured I can make a special access key. Call it stemcell.pem, then have it register itself, then delete it later.

It turns out that the smart people at OpsCode were already n number of steps ahead of me. This was what validation.pem was supposed to be. They even provided a handy :delete_validation_key recipe to take care of the cleanup. Doh!

I copied validation.pem over, re-ran chef-client on the client machine, and what do you know? It works.

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