Parameters:
  PlaybookIAMRole:
    Type: String

Resources:
  PlaybookGatherAppResourceAlarm: 
    Type: "AWS::SSM::Document"
    Properties:
      DocumentType: Automation
      Name: Playbook-Gather-Resources
      Content: 
        schemaVersion: '0.3'
        assumeRole: "{{AutomationAssumeRole}}"
        parameters:
          AlarmARN:
            description: (Required) The Alarm ARN triggering incident.
            type: String
          AutomationAssumeRole:
            type: String
            default: !Ref PlaybookIAMRole
            description: (Optional) The ARN of the role that allows Automation to perform the actions on your behalf.
        outputs:
          - Gather_Resources_For_Alarm.Resources
        mainSteps:
        - name: Gather_Resources_For_Alarm
          action: aws:executeScript
          description: Gather AWS resources related to the Alarm, based on it's Tag
          outputs:
            - Name: Resources
              Selector: $.Payload.ApplicationStackResources
              Type: String
          inputs:
            Runtime: python3.6
            Handler: handler
            InputPayload:
              CloudWatchAlarmARN: '{{AlarmARN}}'
            Script: |-
                import json
                import re
                from datetime import datetime
                import boto3
                import os
                
                def arn_deconstruct(arn):
                  # arn:aws:cloudwatch:us-east-1:754323466686:alarm:mysecretword-canary-alarm
                  arnlist = arn.split(":")
                  service=arnlist[2]
                  region=arnlist[3]
                  accountid=arnlist[4]
                  servicetype=arnlist[5]
                  name=arnlist[6]
                  
                  return {
                    "Service": service,
                    "Region": region,
                    "AccountId": accountid,
                    "Type": servicetype,
                    "Name": name
                  }
                
                def locate_alarm_source(alarm):
                  cwclient = boto3.client('cloudwatch', region_name = alarm['Region'] )
                  alarm_source = {}
                  alarm_detail = cwclient.describe_alarms(AlarmNames=[alarm['Name']])  
                  
                  if len(alarm_detail['MetricAlarms']) > 0:
                    metric_alarm = alarm_detail['MetricAlarms'][0]
                    namespace = metric_alarm['Namespace']
                    
                    # Condition if NameSpace is CloudWatch Syntetics
                    if namespace == 'CloudWatchSynthetics':
                      if 'Dimensions' in metric_alarm:
                        dimensions = metric_alarm['Dimensions']
                        for i in dimensions:
                          if i['Name'] == 'CanaryName':
                            source_name = i['Value']
                            alarm_source['Type'] = namespace
                            alarm_source['Name'] = source_name
                            alarm_source['Region'] = alarm['Region']
                            alarm_source['AccountId'] = alarm['AccountId']
                
                    result = alarm_source
                    return result
                  
                  # #Condition for CompositeAlarms    
                  # if len(alarm_detail['CompositeAlarms']) > 0:
                
                def locate_canary_endpoint(canaryname,region):
                  result = None
                  synclient = boto3.client('synthetics', region_name = region )
                  res = synclient.get_canary(Name=canaryname)
                  canary = res['Canary']
                  if 'Tags' in canary:
                    if 'TargetEndpoint' in canary['Tags']:
                      target_endpoint = canary['Tags']['TargetEndpoint']
                      result = target_endpoint
                      
                  return result
                
                
                def locate_app_tag_value(resource):
                  result = None
                
                  if resource['Type'] == 'CloudWatchSynthetics':
                    synclient = boto3.client('synthetics', region_name = resource['Region'] )
                    res = synclient.get_canary(Name=resource['Name'])
                    canary = res['Canary']
                    if 'Tags' in canary:
                      if 'Application' in canary['Tags']:
                        apptag_val = canary['Tags']['Application']
                        result = apptag_val
                        
                  return result
                
                def locate_app_resources_by_tag(tag,region):
                  result = None
                  
                  # Search CloufFormation Stacks for tag
                  cfnclient = boto3.client('cloudformation', region_name = region )
                  list = cfnclient.list_stacks(StackStatusFilter=['CREATE_COMPLETE','ROLLBACK_COMPLETE','UPDATE_COMPLETE','UPDATE_ROLLBACK_COMPLETE','IMPORT_COMPLETE','IMPORT_ROLLBACK_COMPLETE']  )
                  for stack in list['StackSummaries']:
                    app_resources_list = []
                    stack_name = stack['StackName']
                    stack_details = cfnclient.describe_stacks(StackName=stack_name)
                    stack_info = stack_details['Stacks'][0]
                    if 'Tags' in stack_info:
                      for t in stack_info['Tags']:
                        if t['Key'] == 'Application' and t['Value'] == tag:
                          app_stack_name = stack_info['StackName']
                          app_resources = cfnclient.describe_stack_resources(StackName=app_stack_name)
                          for resource in app_resources['StackResources']:
                            app_resources_list.append(
                              { 
                                'PhysicalResourceId' : resource['PhysicalResourceId'],
                                'Type': resource['ResourceType']
                              }
                            )
                          result =  app_resources_list
                  
                  return result
                def handler(event, context):
                  result = {}
                  arn = event['CloudWatchAlarmARN']
                  alarm = arn_deconstruct(arn)
                  # Locate tag from CloudWatch Alarm
                  
                  
                  alarm_source = locate_alarm_source(alarm) # Identify Alarm Source
                  tag_value = locate_app_tag_value(alarm_source) #Identify tag from source
                  
                  if alarm_source['Type'] == 'CloudWatchSynthetics':
                    endpoint = locate_canary_endpoint(alarm_source['Name'],alarm_source['Region'])
                    result['CanaryEndpoint'] = endpoint
                    
                  # Locate cloudformation with tag
                  resources = locate_app_resources_by_tag(tag_value,alarm['Region'])
                  result['ApplicationStackResources'] = json.dumps(resources) 
                  
                  return result