Deletes stuff that's gone from ec2 from chef

node_dead.rb

require 'chef/knife'

module KnifeNeat
  class NodeDead < Chef::Knife

    banner "knife node dead ENVIRONMENT"

    option :id_source,
           short: '-i SOURCE',
           long: '--id-source SOURCE',
           description: 'Where to receive the instance id: [ec2.instance_id|name], default: ec2.instance_id',
           default: 'ec2.instance_id'

    option :dry_run,
           short: '-n',
           long: '--dry-run',
           description: 'Output items that would have been deleted. No action taken.',
           required: false,
           boolean: true,
           default: false

    deps do
      require 'chef/node'
      require 'chef/search/query'
    end

    def run
      config[:yes] = true
      ui.info('Dry run mode enabled, all following logs are informational only.') if dry_run?

      Chef::Node.list_by_environment(name_args[0]).keys.each do |node_name|
        node = Chef::Node.load(node_name)

        instance_id = case config[:id_source]
                        when 'ec2.instance_id'
                          node[:ec2] && node[:ec2][:instance_id]
                        when 'name'
                          node.name.scan(/(i-[0-9a-f]{8})/).flatten.last
                        else
                          ui.error("Unknown instance id source: #{config[:id_source]}")
                          exit(1)
                      end

        if !instance_id.nil? && !exists?(instance_id)
          delete(node)
        end
      end
    end

    def delete(node)
      ui.info("Deleting node #{node.name}")
      node.destroy unless dry_run?

      clients, start, total = searcher.search('client', "name:#{node.name}")
      clients.each do |client|
        ui.info("Deleting client #{client.name}")
        client.destroy unless dry_run?
      end
    end

    def searcher
      @searcher ||= Chef::Search::Query.new
    end

    def exists?(instance_id)
      instance = instances[instance_id]
      instance.exists? && instance.status.to_s != 'terminated'
    end

    def instances
      @instances ||= AWS::EC2.new.instances
    end

    def dry_run?
      config[:dry_run]
    end
  end
end