Earlier today^Wyesterday, Opscode previewed a new feature of the upcoming Chef 0.10, Knife Plugins. I’ve been excited about this feature since Dan DeLeo first created the ticket for it. I already created the “grep” plugin that Dan illustrates on the blog post, and it is quite useful already (and I only have a few systems!).
A few months ago, I wrote a silly library that will retrieve the list of Canonical’s released AMIs. They make this available as a text file per distribution codename (lucid, maverick, etc), and my library supports that. For even greater silliness, but perhaps usefulness, I wrote a knife plugin to retrieve the AMI data. The code is really simple.
The run method processes the name_args (see the Knife Plugin Documentation) for the distribution and optionally a type. Lets see an example of what this means.
First, usage:
% knife ec2 amis ubuntu -h
knife ec2 amis ubuntu DISTRO [TYPE]
-s, --server-url URL Chef Server URL
-k, --key KEY API Client Key
--color Use colored output
-c, --config CONFIG The configuration file to use
--defaults Accept default values for all questions
-e, --editor EDITOR Set the editor to use for interactive commands
-E, --environment ENVIRONMENT Set the Chef environment
-F, --format FORMAT Which format to use for output
--no-color Don't use colors in the output
-n, --no-editor Do not open EDITOR, just accept the data as is
-u, --user USER API Client Username
--print-after Show the data after a destructive operation
-V, --verbose More verbose output. Use twice for max verbosity
-v, --version Show chef version
-y, --yes Say yes to all prompts for confirmation
-h, --help Show this messageThe name_args we can pass are DISTRO and TYPE, TYPE being optional. The rest of the options are built into knife and available to every sub-command. Let’s pick a distro. My favorite these days is lucid:
% knife ec2 amis ubuntu lucid ap_northeast_large: ami-580fa459 ap_northeast_large_ebs: ami-5e0fa45f ap_northeast_small: ami-4c0fa44d ap_northeast_small_ebs: ami-5c0fa45d ap_southeast_large: ami-c692ec94 ap_southeast_large_ebs: ami-f092eca2 ap_southeast_small: ami-2492ec76 ap_southeast_small_ebs: ami-f292eca0 eu_west_large: ami-631f2b17 eu_west_large_ebs: ami-3d1f2b49 eu_west_small: ami-a11e2ad5 eu_west_small_ebs: ami-311f2b45 us_east_large: ami-fa01f193 us_east_large_ebs: ami-3202f25b us_east_small: ami-7000f019 us_east_small_ebs: ami-3e02f257 us_west_large: ami-e1bfefa4 us_west_large_ebs: ami-f5bfefb0 us_west_small: ami-19bfef5c us_west_small_ebs: ami-ebbfefae
For the DISTRO, I can use any of the codenames that Canonical makes available, including karmic, lucid, maverick and even natty at the time of this writing. The value on the left is the TYPE. Lets see what happens when I pass one of those:
% knife ec2 amis ubuntu lucid us_west_small ami-19bfef5c
This returns just the AMI. We can feed this into an environment variable or just copy and paste it into a “knife ec2 server create” command for the “-I ami” option.
A note about the naming, I classed it under the ec2 sub-command space since it is most relevant there. Further, I used “amis ubuntu” rather than “ubuntu amis” because theoretically other plugins could be written to retrieve other platforms. There’s a couple bugs I know about already and will fix them later. Enjoy!