Class: CfnGuardian::Stacks::Resources

Inherits:
Object
  • Object
show all
Includes:
CfnDsl::CloudFormation
Defined in:
lib/cfnguardian/stacks/resources.rb

Instance Method Summary collapse

Constructor Details

#initialize(template) ⇒ Resources

Returns a new instance of Resources.



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# File 'lib/cfnguardian/stacks/resources.rb', line 10

def initialize(template)
  @template = template
end

Instance Method Details

#add_alarm(alarm) ⇒ Object 



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# File 'lib/cfnguardian/stacks/resources.rb', line 33

def add_alarm(alarm)
  actions = alarm.alarm_action.kind_of?(Array) ? alarm.alarm_action.map{|action| Ref(action)} : [Ref(alarm.alarm_action)]
  actions.concat alarm.maintenance_groups.map {|mg| Ref(mg)} if alarm.maintenance_groups.any?
  use_search = alarm.search_expression.is_a?(String) && !alarm.search_expression.strip.empty?
  use_anomaly_detection = alarm.anomaly_detection == true

  @template.declare do
    CloudWatch_Alarm("#{alarm.resource_hash}#{alarm.group}#{alarm.name.gsub(/[^0-9a-zA-Z]/i, '')}#{alarm.type}"[0..255]) do
      ActionsEnabled true
      AlarmDescription "Guardian alarm #{alarm.name} for the resource #{alarm.resource_id} in alarm group #{alarm.group}"
      AlarmName CfnGuardian::CloudWatch.get_alarm_name(alarm)
      ComparisonOperator alarm.comparison_operator
      EvaluationPeriods alarm.evaluation_periods
      # Threshold and ThresholdMetricId are mutually exclusive on AWS::CloudWatch::Alarm -
      # an anomaly detection alarm uses ThresholdMetricId (set below) instead of a static Threshold.
      Threshold alarm.threshold unless use_anomaly_detection
      AlarmActions actions
      OKActions actions unless alarm.ok_action_disabled
      TreatMissingData alarm.treat_missing_data unless alarm.treat_missing_data.nil?
      DatapointsToAlarm alarm.datapoints_to_alarm unless alarm.datapoints_to_alarm.nil?

      if use_search
        aggregation = alarm.search_aggregation || 'MAX'
        Metrics [
          {
            Id: 'search_expression',
            Expression: alarm.search_expression,
            Period: alarm.period,
            ReturnData: false
          },
          {
            Id: 'aggregate',
            Expression: "#{aggregation}(search_expression)",
            ReturnData: true
          }
        ]
      elsif use_anomaly_detection
        band_width = alarm.standard_deviation || 2
        metric_stat = {
          Metric: {
            Namespace: alarm.namespace,
            MetricName: alarm.metric_name
          },
          Period: alarm.period,
          Stat: alarm.extended_statistic.nil? ? alarm.statistic : alarm.extended_statistic
        }
        metric_stat[:Metric][:Dimensions] = alarm.dimensions.map {|k,v| {Name: k, Value: v}} unless alarm.dimensions.nil?
        metric_stat[:Unit] = alarm.unit unless alarm.unit.nil?

        Metrics [
          {
            Id: 'm1',
            MetricStat: metric_stat,
            ReturnData: true
          },
          {
            Id: 'ad1',
            Expression: "ANOMALY_DETECTION_BAND(m1, #{band_width})",
            Label: "#{alarm.metric_name} (expected)",
            ReturnData: true
          }
        ]
        ThresholdMetricId 'ad1'
        EvaluateLowSampleCountPercentile alarm.evaluate_low_sample_count_percentile unless alarm.evaluate_low_sample_count_percentile.nil?
      else
        Dimensions alarm.dimensions.map {|k,v| {Name: k, Value: v}} unless alarm.dimensions.nil?
        Statistic alarm.statistic if alarm.extended_statistic.nil?
        Period alarm.period
        MetricName alarm.metric_name
        Namespace alarm.namespace
        ExtendedStatistic alarm.extended_statistic unless alarm.extended_statistic.nil?
        EvaluateLowSampleCountPercentile alarm.evaluate_low_sample_count_percentile unless alarm.evaluate_low_sample_count_percentile.nil?
        Unit alarm.unit unless alarm.unit.nil?
      end
    end
  end
end

#add_composite_alarm(alarm) ⇒ Object 



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# File 'lib/cfnguardian/stacks/resources.rb', line 128

def add_composite_alarm(alarm)
  @template.declare do
    CloudWatch_CompositeAlarm(alarm.name.gsub(/[^0-9a-zA-Z]/i, '')) do
      
      AlarmDescription alarm.description
      AlarmName "guardian-#{alarm.name}"
      AlarmRule alarm.rule
      
      unless alarm.alarm_action.nil?
        ActionsEnabled true
        AlarmActions [Ref(alarm.alarm_action)]
        InsufficientDataActions [Ref(alarm.alarm_action)]
        OKActions [Ref(alarm.alarm_action)]
      end
      
    end
  end
end

#add_event(event) ⇒ Object 



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# File 'lib/cfnguardian/stacks/resources.rb', line 111

def add_event(event)
  @template.declare do          
    Events_Rule("#{event.group}#{event.type}#{event.hash}"[0..255]) do
      State 'ENABLED'
      Description "Guardian scheduled #{event.group} #{event.type}"
      ScheduleExpression "cron(#{event.cron})"
      Targets([
        { 
          Arn: FnGetAtt(event.target, :Arn),
          Id: event.hash,
          Input: FnSub(event.payload)
        }
      ])
    end
  end
end

#add_event_subscription(subscription) ⇒ Object 



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# File 'lib/cfnguardian/stacks/resources.rb', line 163

def add_event_subscription(subscription)
  event_pattern = {}
  event_pattern['detail-type'] = [subscription.detail_type] unless subscription.detail_type.empty?
  event_pattern['source'] = [subscription.source]
  event_pattern['resources'] = [subscription.resource_arn] unless subscription.resource_arn.empty?
  event_pattern['detail'] = subscription.detail unless subscription.detail.empty?

  @template.declare do
    Events_Rule("#{subscription.group}#{subscription.name}#{subscription.hash}"[0..255]) do
      State subscription.enabled ? 'ENABLED' : 'DISABLED'
      Description "Guardian event subscription #{subscription.group} #{subscription.name} for resource #{subscription.resource_id}"
      EventPattern FnSub(event_pattern.to_json)
      Targets [
        {
          Arn: Ref(subscription.topic),
          Id: "#{subscription.topic}Notifier"
        }
      ]
    end
  end
end

#add_metric_filter(filter) ⇒ Object 



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# File 'lib/cfnguardian/stacks/resources.rb', line 147

def add_metric_filter(filter)
  @template.declare do
    Logs_MetricFilter("#{filter.name.gsub(/[^0-9a-zA-Z]/i, '')}#{filter.type}") do
      LogGroupName filter.log_group
      FilterPattern filter.pattern
      MetricTransformations([
        {
          MetricValue: filter.metric_value,
          MetricName: filter.metric_name,
          MetricNamespace: filter.metric_namespace
        }
      ])
    end
  end
end

#build_template(resources) ⇒ Object 



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# File 'lib/cfnguardian/stacks/resources.rb', line 14

def build_template(resources)
  resources.each do |resource|
    case resource.type
    when 'Alarm'
      add_alarm(resource)
    when 'Event'
      add_event(resource)
    when 'Composite'
      add_composite_alarm(resource)
    when 'MetricFilter'
      add_metric_filter(resource)
    when 'EventSubscription'
      add_event_subscription(resource)
    else
      puts "Warn: #{resource.type} is a unsuported resource type"
    end
  end
end