Customizing Chef for Fun and Profit
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This document discusses customizing Chef for operations. It outlines the Chef client workflow including authenticating to the server, loading the node configuration, running handlers, synchronizing cookbooks, converging resources to change the node, and finalizing the run. It encourages accessing the run status object in handlers and exploring the Chef codebase. Key aspects that can be customized include plugins, handlers, events, and the client configuration.
![@jonlives
Ohai Plugins - v6
provides ‘awesome’
!
awesome Mash.new
awesome[:sauce] = "Sricacha"
awesome[:level] = "11"](https://image.slidesharecdn.com/chefconf2014-140418021531-phpapp01/85/Customizing-Chef-for-Fun-and-Profit-22-320.jpg)
![@jonlives
Ohai Plugins - v7 (Coming soon!)
Ohai.plugin(:Awesome) do
provides "awesome"
collect_data(:darwin) do
awesome Mash.new
awesome[:sauce] = “Sriracha"
awesome[:level] = 11
end
end](https://image.slidesharecdn.com/chefconf2014-140418021531-phpapp01/85/Customizing-Chef-for-Fun-and-Profit-23-320.jpg)
![@jonlives
Ohai Plugins - client.rb / solo.rb
Ohai::Config[:plugin_path] << /<path>/plugins](https://image.slidesharecdn.com/chefconf2014-140418021531-phpapp01/85/Customizing-Chef-for-Fun-and-Profit-24-320.jpg)
Customizing Chef for Fun and Profit
- 1. Customizing Chef For Fun and Profit
- 2. @jonlives Jon Cowie Sr Operations Engineer
- 4. @jonlives
- 5. @jonlives
- 6. @jonlives Beginning of 2010 Today
- 8. @jonlives Chef at Etsy • Open Source Chef Server • ~1500 Nodes • CentOS, some Mac OS X
- 11. @jonlives Absorb what is useful. Discard what is useless.
- 12. @jonlives “I am not smart enough to build an ontology … that can encompass all the variations in infrastructure. Nobody is, the world moves too fast.”
- 13. @jonlives There is no magic pill.
- 16. @jonlives
- 19. @jonlives
- 20. @jonlives Get Config Data / Initialize • Load client.rb • Server URL • Auth Credentials • Paths • Run ohai • Collect attributes • Plugins!
- 21. @jonlives Ohai Plugins • Add attributes to your node • Executed at start of run • Single Ruby file • Highest precedence
- 22. @jonlives Ohai Plugins - v6 provides ‘awesome’ ! awesome Mash.new awesome[:sauce] = "Sricacha" awesome[:level] = "11"
- 23. @jonlives Ohai Plugins - v7 (Coming soon!) Ohai.plugin(:Awesome) do provides "awesome" collect_data(:darwin) do awesome Mash.new awesome[:sauce] = “Sriracha" awesome[:level] = 11 end end
- 24. @jonlives Ohai Plugins - client.rb / solo.rb Ohai::Config[:plugin_path] << /<path>/plugins
- 25. @jonlives Authenticate / Register • Authenticate to Server • <clientkey>.pem • Register if not already registered • <validation>.pem • If both fail, go directly to jail.
- 26. @jonlives Load / Build Node • Download node • Combine attributes • Expand run_list • Order matters! • Create RunStatus object • Run start handlers
- 27. @jonlives Handlers • Respond to specific situations • Start, Report, Exception • Common Code
- 28. @jonlives Handlers - Common Code require "chef/handler" ! class HandlerName < Chef::Handler def report # Ruby code goes here end end
- 29. @jonlives Handlers - client.rb / solo.rb require “/path_to/mystarthandler.rb" ! my_start_handler = MyStartHandler.new ! start_handlers << my_start_handler
- 30. @jonlives Synchronize Cookbooks • Get cookbook files list • Only required recipes, files & templates • Compares to local cache • Download changes
- 31. @jonlives Set up RunContext • Cookbook Collection • Definitions List • Events • Notifications • Node • Resource Collection • Empty for now…
- 32. @jonlives Events • Respond to interesting events • Pub / Sub model • EventDispatch::Base • Formatter • Custom Subscriber
- 33. @jonlives Events - Custom Subscriber require “chef/event_dispatch/base" ! class AwesomeSubscriber < Chef::EventDispatch::Base def run_started(run_status) … end # Method for each interesting event end
- 34. @jonlives Events - Register Subscriber require "chef/handler" require “/path/awesome_subscriber.rb' ! class AwesomeSubscriberStartHandler < Chef::Handler def report event_dispatcher_subscriber = AwesomeSubscriber.new @run_status.events.register(event_dispatcher_subscriber) end end
- 35. @jonlives Load Cookbook Data • Populate Resource Collection • Libraries • Attributes • Resources / Providers • Definitions • Recipes
- 36. @jonlives Converge Node • Actually changes node • Apply resource collection • Again, order matters!
- 37. @jonlives Finalize • Successful Run • Save Node • Report Handlers • Failed Run • Exception Handlers • 💩
- 38. @jonlives Report & Exception Handlers def report if @run_status.success? # Do a happy dance elsif @run_status.failed? # Sad panda. end end
- 39. @jonlives Handlers - client.rb / solo.rb require “/var/chef/handlers/mystarthandler.rb" require "/var/chef/handlers/mynewhandler.rb" ! my_start_handler = MyStartHandler.new my_new_handler = MyNewHandler.new ! start_handlers << my_start_handler report_handlers << my_new_handler exception_handlers << my_new_handler
- 40. @jonlives That RunStatus Object Again… • Accessible to handlers • Run status & timings • Exception and Backtrace • All & updated resources • RunContext • Node object
- 41. @jonlives Don’t fear the code! • https://github.com/opscode/chef • lib/chef/handler.rb • lib/chef/run_status.rb • lib/chef/run_context.rb • lib/chef/event_dispatch/base.rb
- 43. @jonlives Criteria for Customization Simplicity Modularity Visibility Maintainability Scalability
- 45. @jonlives Thanks! Questions? ! Office Hours @ 3.15, Marina Room @jonlives / http://jonliv.es / jcowie@etsy.com