cloudwatch.rb

include Opscode::Aws::CloudWatch

use_inline_resources

def whyrun_supported?
  true
end

# Make options for cloudwatch API
def build_cwh_options
  options = {
    alarm_name: new_resource.alarm_name,
    period: new_resource.period,
    evaluation_periods: new_resource.evaluation_periods,
    threshold: new_resource.threshold.to_f,
    comparison_operator: new_resource.comparison_operator,
    metric_name: new_resource.metric_name,
    namespace: new_resource.namespace,
  }
  options[:alarm_description] = new_resource.alarm_description if new_resource.alarm_description
  if new_resource.actions_enabled
    if new_resource.ok_actions.empty? && new_resource.alarm_actions.empty? && new_resource.insufficient_data_actions.empty?
      raise 'No actions provided for any of OK/ALARM/INSUFFICIENT'
    else
      options[:actions_enabled] = true if new_resource.actions_enabled
      options[:ok_actions] = new_resource.ok_actions if new_resource.ok_actions.any?
      options[:alarm_actions] = new_resource.alarm_actions if new_resource.alarm_actions.any?
      options[:insufficient_data_actions] = new_resource.insufficient_data_actions if new_resource.insufficient_data_actions.any?
    end
  end
  options[:statistic] = new_resource.statistic if new_resource.statistic
  options[:dimensions] = new_resource.dimensions if new_resource.dimensions
  options[:extended_statistic] = new_resource.extended_statistic if new_resource.extended_statistic
  options[:unit] = new_resource.unit if new_resource.unit
  options
end

# Function to check if the alarm needs to be updated.
# Params
# type - any, alarm_action
# p - boolen option for alarm_action
def cwh_if_changed(type, *p)
  options = { alarm_names: [new_resource.alarm_name], max_records: 1 }
  resp = cwh.describe_alarms(options)
  if !resp.metric_alarms.empty?
    if type == 'any'
      new_params = build_cwh_options
      new_params.each_key do |k|
        if resp.metric_alarms[0][k].nil? || resp.metric_alarms[0][k].to_s.empty?
          return true
        elsif new_params[k].is_a?(Array) || resp.metric_alarms[0][k].is_a?(Array)
          if new_params[k].length != resp.metric_alarms[0][k].length
            return true
          else
            new_params[k].each_index do |n|
              if resp.metric_alarms[0][k][n].nil? || resp.metric_alarms[0][k][n].to_s.empty?
                return true
              elsif new_params[k][n].is_a?(Hash) || resp.metric_alarms[0][k][n].is_a?(Hash)
                if new_params[k][n].length != resp.metric_alarms[0][k][n].length
                  return true
                else
                  new_params[k][n].each_key { |m| return true unless resp.metric_alarms[0][k][n][m].nil? || resp.metric_alarms[0][k][n][m].to_s.empty? || new_params[k][n][m] == resp.metric_alarms[0][k][n][m] }
                end
              else
                return true unless resp.metric_alarms[0][k][n].nil? || resp.metric_alarms[0][k][n].to_s.empty? || new_params[k][n] == resp.metric_alarms[0][k][n]
              end
            end
          end
        else
          return true unless new_params[k] == resp.metric_alarms[0][k]
        end
      end
    elsif type == 'alarm_action'
      return true unless resp.metric_alarms[0].actions_enabled.to_s == p.join
    end
    false
  else
    true
  end
end

# Create action will fire put_metric_alarm of cloudwatch API, will update the alarm if found changes in parameters.
action :create do
  if cwh_if_changed('any')
    converge_by("create/update metric #{new_resource.alarm_name}") do
      Chef::Log.debug("create/update metric #{new_resource.alarm_name}")
      options = build_cwh_options
      cwh.put_metric_alarm(options)
      new_resource.updated_by_last_action(true)
    end
  else
    Chef::Log.debug("No action required for metric #{new_resource.alarm_name}")
  end
end

# Delete action will fire delete_alarms of cloudwatch API.
action :delete do
  converge_by("delete metric #{new_resource.alarm_name}") do
    Chef::Log.debug("delete metric #{new_resource.alarm_name}")
    options = { alarm_names: [new_resource.alarm_name] }
    cwh.delete_alarms(options)
    new_resource.updated_by_last_action(true)
  end
end

# Disable action will fire disable_alarm_actions of cloudwatch API. if not disabled already.
action :disable_action do
  if cwh_if_changed('alarm_action', 'false')
    converge_by("disable alarm action metric #{new_resource.alarm_name}") do
      Chef::Log.debug("disable alarm action metric #{new_resource.alarm_name}")
      options = { alarm_names: [new_resource.alarm_name] }
      cwh.disable_alarm_actions(options)
      new_resource.updated_by_last_action(true)
    end
  else
    Chef::Log.debug("No action required for metric #{new_resource.alarm_name}")
  end
end

# Enable action will fire disable_alarm_actions of cloudwatch API. if not enabled already.
action :enable_action do
  if cwh_if_changed('alarm_action', 'true')
    converge_by("enable alarm action metric #{new_resource.alarm_name}") do
      Chef::Log.debug("enable alarm action metric #{new_resource.alarm_name}")
      options = { alarm_names: [new_resource.alarm_name] }
      cwh.enable_alarm_actions(options)
      new_resource.updated_by_last_action(true)
    end
  else
    Chef::Log.debug("No action required for metric #{new_resource.alarm_name}")
  end
end