Cross-Region Replication Monitor (CRR Monitor) automatically checks the replication status of Amazon S3 objects across all AWS Regions in a customer's account, and provides near real-time metrics and failure notifications to help customers identify failures and troubleshoot problems.
The Guidance provisions the necessary AWS services to monitor and view replication status, including AWS Lambda, Amazon CloudWatch, Amazon Simple Notification Service (Amazon SNS), AWS CloudTrail, Amazon Simple Queue Service (Amazon SQS), and Amazon DynamoDB, and offers an option to use Amazon Kinesis Data Firehose to archive replication metadata in Amazon S3.
https://aws.amazon.com/solutions/implementations/cross-region-replication-monitor/