To use the python for auto-snapshot.

py_aws_auto_snapshot.py

import os
import datetime
from datetime import timezone
import boto3 # Import from basic library (base on aws lambda)

"""
os.environ: {
  'aws_access_key_id', <= aws's id.
  'aws_secret_access_key', <= aws's key.
  'retention_days', <= this is a retention.
  'region_names' <= this is your own region.
}
"""

def lambda_handler(event=None, context=None):
    print('AWS snapshot backups starting at {0}'.format(
            datetime.datetime.now(timezone.utc)
        )
    )
    # Get all regin names by string(ap-xxx,us-xxx).
    regions = map(lambda x: x.strip(), os.environ['region_names'].split(','))
    for region in regions:
        ec2 = boto3.resource(
            'ec2',
            aws_access_key_id=os.environ['aws_access_key_id'],
            aws_secret_access_key=os.environ['aws_secret_access_key'],
            region_name=region
        )
        instances = ec2.instances.filter(
            Filters=[{'Name': 'instance-state-name', 'Values': ['running']}]
        )
        # If this instance has a pair of '{snapshot: true}', and then to create the snapshot.
        filter_objects = [
            {
                'instance_id': instance.id,
                'instance_name': [
                    t.get('Value') for t in instance.tags if t.get('Key') == 'Name'
                ][0]
            } for instance in instances
                    if instance.tags
                        for tag in instance.tags
                            if tag.get('Key') == 'snapshot' and tag.get('Value') == 'true'
        ]

        for instance in filter_objects:
            for volume in ec2.volumes.filter(
                Filters=[{'Name': 'attachment.instance-id', 'Values': [instance['instance_id']]}]):
                description = '{0};{1};{2}'.format(
                    instance['instance_name'],
                    volume.volume_id,
                    datetime.datetime.now().strftime("%Y%m%d")
                )
                # create ebs snaphost
                try:
                    checks = [
                        snapshot.description for snapshot in volume.snapshots.all()
                            if snapshot.description
                    ]
                    if description not in checks:
                        # Create new snapshot.
                        snapshot_name = 'Auto_Backup:{0}'.format(instance['instance_name'])
                        if volume.create_snapshot(
                            TagSpecifications=[
                                {
                                    'ResourceType': 'snapshot',
                                    'Tags': [
                                        {
                                            'Key': 'Name',
                                            'Value': snapshot_name
                                        }
                                    ]
                                }
                            ],
                            VolumeId=volume.volume_id,
                            Description=description
                        ):
                            print("Snapshot created with description {0}".format(description))
                    else:
                         print('The snaphost does exist, {0}'.format(description))
                except Exception as e:
                    print("Create the snapshot error {0}:".format(e))
                    pass

                # Delete over-expired snapshots.
                try:
                    for snapshot in volume.snapshots.all():
                        # Default retention's day is 30.
                        retention_days = int(os.environ.get('retention_days', 30))
                        now_time = datetime.datetime.now(timezone.utc)
                        time_checking = (now_time - snapshot.start_time.replace(tzinfo=timezone.utc) > datetime.timedelta(days=retention_days))
                        if (
                            snapshot.tags and
                            time_checking and
                            [
                                t.get('Value') for t in snapshot.tags
                                    if t.get('Key') == 'Name' and t.get('Value').startswith('Auto_Backup')
                            ]
                        ):
                            print('Deleting snapshot [{0} - {1}]'.format(snapshot.snapshot_id, snapshot.description))
                            snapshot.delete()
                except Exception as e:
                    print("Delete the snapshot error {0}:".format(e))
                    pass

        print(
            'AWS snapshot backups completed at region:{0}; {1}'.format(
                region, datetime.datetime.now()
            )
        )
    return True