DynamoDB table backup using AWS Lambda (including cleanup of obsolete backups after a specified time)

dynamodb_backup_lambda.py

import datetime
import os

import boto3
import logging

DAYS_UNTIL_OBSOLETE = 90
BACKUP_NAME_PREFIX = 'auto_'
BACKUP_TABLE_TAG_KEY = 'backup'
BACKUP_TABLE_TAG_VALUE = 'true'

LOGGER = logging.getLogger()
LOGGER.setLevel(logging.INFO)

def lambda_handler(event, context):
    client = boto3.client('dynamodb')
    timestamp = datetime.datetime.now().strftime('%Y%m%d-%H%M%S')
    
    created_backups = 0
    tables = client.list_tables()
    for table_name in tables['TableNames']:
        table_description = client.describe_table(TableName=table_name)
        table_tags = client.list_tags_of_resource(ResourceArn=table_description['Table']['TableArn'])
        backup_enabled = False
        for tag in table_tags['Tags']:
            if tag['Key'] == BACKUP_TABLE_TAG_KEY and tag['Value'] == BACKUP_TABLE_TAG_VALUE:
                backup_enabled = True
        if not backup_enabled:
            continue
        LOGGER.info('creating backup for table ' + table_name)
        client.create_backup(TableName=table_name, BackupName=BACKUP_NAME_PREFIX + table_name + '_' + timestamp)
        created_backups += 1
    
    removed_backups = 0
    obsolete_time = datetime.datetime.now() - datetime.timedelta(days=DAYS_UNTIL_OBSOLETE)
    obsolete_backups = client.list_backups(TimeRangeUpperBound=obsolete_time)
    LOGGER.info('removing obsolete backups')
    for obsolete_backup in obsolete_backups['BackupSummaries']:
        if not obsolete_backup['BackupName'].startswith(BACKUP_NAME_PREFIX):
            continue
        LOGGER.info('removing backup ' + obsolete_backup['BackupName'])
        client.delete_backup(BackupArn=obsolete_backup['BackupArn'])
        removed_backups += 1

    return 'Created ' + str(created_backups) + ' backups, removed ' + str(removed_backups)