Blue Matador automatically watches SNS topics and will create an event when statistics are out of the ordinary. The number of published messages and the number of failed notifications are watched for anomalies.
SNS provides metrics on the number of messages published to a particular topic. Blue Matador continuously monitors each topic and creates an anomaly when an unexpected number of messages are published. Such anomalies could signal issues in the code that sends messages to the topic. To troubleshoot an anomaly in this metric:
SNS increments the Failed Notifications metric whenever a message fails to be sent to a subscriber. For SQS, email, SMS, or mobile push endpoints, AWS will retry failures and will only increment the metric when no further retries will be attempted. This metric does not include messages that were rejected by subscription filter policies. Failed notifications could result in parts of your system not getting the data they need from SNS.
To troubleshoot failed notifications, enable logging to CloudWatch. Checking the logs will allow you to tell which subscribers are failing, as well as the status codes they are returning.