delete the snapshot if its volume is deleted

I need to delete the snapshot of my Elastic Block Store volume whose EBS volumes are deleted. I would like to do this using a Lambda function. I wrote a script which will give me false if the EBS volume does not exist. How can I modify it to delete any related snapshots?

def get_snapshots():
    account_ids = list()
    account_ids.append( boto3.client('sts').get_caller_identity().get('Account'))
    return ec2.describe_snapshots(OwnerIds=account_ids)
 
def volume_exists(volume_id):
    if not volume_id: return ''
    try:
        ec2.describe_volumes(VolumeIds=[volume_id])
        return True
    except ClientError:
        return False
 

 
def lambda_handler(event, context):

    with open('/tmp/report.csv', 'w') as csvfile:
        writer = csv.writer(csvfile)
        writer.writerow([
        'volume exists'
        ])
        snaps = get_snapshots()
        
        for snap in snaps.get('Snapshots'):
            writer.writerow([
            
            str(volume_exists(snap['VolumeId']))
            ])

Any suggestion?

Here's some code that will delete snapshots that don't have an existing volume:

import boto3

ec2_client = boto3.client('ec2')

# Make a list of existing volumes
volume_response = ec2_client.describe_volumes()
volumes = [volume['VolumeId'] for volume in volume_response['Volumes']]

# Find snapshots without existing volume
snapshot_response = ec2_client.describe_snapshots(OwnerIds=['self'])

for snapshot in snapshot_response['Snapshots']:
    if snapshot['VolumeId'] not in volumes:
        delete_response = ec2_client.delete_snapshot(SnapshotId=snapshot['SnapshotId'])

Or, here's a version that uses resource instead of client:

import boto3

ec2_resource = boto3.resource('ec2')

# Make a list of existing volumes
all_volumes = ec2_resource.volumes.all()
volumes = [volume.volume_id for volume in all_volumes]

# Find snapshots without existing volume
snapshots = ec2_resource.snapshots.filter(OwnerIds=['self'])

for snapshot in snapshots:
    if snapshot.volume_id not in volumes:
        snapshot.delete()

If they work as you wish, you'll need to incorporate it into a Lambda function.

(In addition to the license granted under the terms of service of this site the contents of this post are licensed under MIT-0.)