LambdaSnapshotDelete.yaml

AWSTemplateFormatVersion: '2010-09-09'
Description: 'CFN template to create a lambda and a event to trigger lambda at a certain frequency'

Parameters:
    EnvName:
        Type: String
        Description: 'Name of an environment. ''dev'', ''staging'', ''prod'' and any name.'
        Default: dev
    LambdaServiceRole:
        Type: String
        Description: 'role of lambda for snapshotting'
        Default: 'arn:aws:iam::952408268520:role/service-role/abs-snapshot-role-xznsj5je'
    VolumeID:
        Type: String
        Description: 'Volume to be snapshotted'
        Default: vol-06ce286891e0e83a4
        
    numberOfSnapshotsToRetain:
       Type: Number
       Description: 'How many snapshots do you want to retain as backup'
       Default: 5
       
    SnapshotRegion:
       Type: String
       Description: ' Region in which your EBS snapshot is stored'
       Default: 'ca-central-1'
       
    applicationName: 
      Type: String
      Description: 'Name of the application to tag the volume snapshot with'
      Default: 'JenkinsMasterVolumeSnapshotBackup'  
      
    rateOfDeletingSnapshot:
       Type: String
       Description: 'what is the frequency of checking for older snapshot'
       Default: 'rate(10 minutes)'           
        
Resources: 
            
    ScheduledRuleForSnapshotDeletion: 
      DependsOn: LambdaFunctionToDeleteSnapshot 
      Type: AWS::Events::Rule
      Properties: 
        Description: "ScheduledRule for LambdaFunctionToDeleteSnapshot trigger"
        ScheduleExpression: !Ref rateOfDeletingSnapshot
        State: "ENABLED"
        Targets: 
            - Arn: !GetAtt 
                - LambdaFunctionToDeleteSnapshot
                - Arn
              Id: LambdaFunctionToDeleteSnapshot

            
    PermissionForEventsToInvokeSnapshotDeletionLambda: 
      DependsOn: ScheduledRuleForSnapshotDeletion
      Type: AWS::Lambda::Permission
      Properties: 
        FunctionName: !Ref LambdaFunctionToDeleteSnapshot
        Action: "lambda:InvokeFunction"
        Principal: "events.amazonaws.com"
        SourceArn: 
          Fn::GetAtt: 
            - "ScheduledRuleForSnapshotDeletion"
            - "Arn"            
                    
    LambdaFunctionToDeleteSnapshot:
       Type: AWS::Lambda::Function
       Properties: 
         FunctionName:
           Fn::Sub: EBS-snapshotDeleter-lambda-function-${EnvName}
         Runtime: python2.7
         Code:
           ZipFile: |
               import boto3;
               import datetime;
               import os;
               import operator;
               
               def delete_snapshot(snapshot_id, reg):
                   print "Deleting snapshot %s " % (snapshot_id)
                   try:  
                       ec2resource = boto3.resource('ec2', region_name=reg)
                       snapshot = ec2resource.Snapshot(snapshot_id)
                       snapshot.delete()
                   except ClientError as e:
                       print "Caught exception: %s" % e
                   return
               
               def lambda_handler(event, context):
                   ec2 = boto3.client('ec2')
                   ts = datetime.datetime.now()
                   volumeID = os.environ['volumeID']
                   applicationName = os.environ['applicationName']
                   SnapshopTagKey = 'JenkinsMasterVolumeSnapshotBackup'
                   reg = os.environ['SnapshotRegion']
                   numberOfSnapshotsToRetain = os.environ['numberOfSnapshotsToRetain']
                   print "Deleting older snapshots from %s at %s" % ( volumeID , datetime.datetime.now())
                   # do snapshot
                   result = ec2.describe_snapshots( Filters=[
                      {
                           'Name': 'tag:Application',
                           'Values': [applicationName]
                       },
                   ] )
                   for snapshot in result['Snapshots']:
                       print "Checking snapshot %s which was created on %s" % (snapshot['SnapshotId'],snapshot['StartTime'])
                   length = len(result['Snapshots'])
                   print length
                   # Sort snapshots by creation time and delete the oldest x numbers
                   for snapshot in (sorted(result['Snapshots'], key=lambda k: k['StartTime'])):
                       print "Checking age of snapshot %s which was created on %s" % (snapshot['SnapshotId'],snapshot['StartTime'])
                       if (length >numberOfSnapshotsToRetain):
                           print " snapshot %s is  OLD which was created on %s. DELETING !" % (snapshot['SnapshotId'],snapshot['StartTime'])
                           delete_snapshot(snapshot['SnapshotId'], reg)
                           length = length -1
                       else:
                           print ("Not an OLD snapshots. Number of snapshot to retian set to "+ str(numberOfSnapshotsToRetain))
                
         Handler: index.lambda_handler
         MemorySize: 128
         Timeout: 10
         Role: !Ref LambdaServiceRole
         Environment:
            Variables:
               volumeID: !Ref VolumeID
               numberOfSnapshotsToRetain: !Ref numberOfSnapshotsToRetain
               SnapshotRegion: !Ref SnapshotRegion
               applicationName: !Ref applicationName