Knife-cloud Gem: Introduction & Knife Plugin Development Using It

Reposted from – Clogeny, An Msys Company

Chef Software, Inc. has released knife-cloud gem. This article talks about what is the knife-cloud gem and how you can use it to develop your custom knife-cloud plugin.

Knife is a CLI tool used for communication between local chef-repo and the Chef Server. There are a couple of knife subcommands supported by Chef, e.g., knife bootstrap, knife cookbook, knife node, knife client, knife ssh, etc. Knife plugin is an extension of the knife commands to support additional functionality. There are about 11 knife plugins managed by Chef and a lot more managed by the community.

The concept of knife-cloud came up as we have a growing number of cloud vendors, and therefore a number of knife plugins, to support the cloud specific operations. The knife-cloud plugins use cloud specific APIs to provision a VM and bootstrap it with Chef. These plugins perform a number of common tasks, such as connection to the node using SSH or WinRM and bootstrapping the node with Chef. The knife-cloud (gem) has been designed to integrate the common tasks of all knife cloud plugins. As a developer of a knife cloud plugin, you will not have to worry about writing the generic code in your plugin. More importantly, if there is any bug or change in the generic code of the knife plugin, the fix would be done in knife-cloud itself. Today we need to apply such changes across all the knife plugins that exist.

Knife-cloud is open source available at: https://github.com/opscode/knife-cloud.
You may refer to https://github.com/opscode/knife-cloud#writing-your-custom-plugin about the steps to write your custom knife cloud plugin.

Clogeny Technologies has written a knife-cloud scaffolder (https://github.com/ClogenyTechnologies/knife-cloud-scaffolder) to make your job even simpler. The scaffolder generates the stub code for you with appropriate TODO comments to guide you in writing your cloud specific code.

To use the knife-cloud-scaffolder:
– git clone https://github.com/ClogenyTechnologies/knife-cloud-scaffolder
– Update properties.json
– Run the command: ruby knifecloudgen.rb E.g., ruby knifecloudgen.rb ./knife-myplugin ./properties.json

Your knife-myplugin stub will be ready. Just add your cloud specific code to it and you should be ready to use your custom plugin.

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