Question

A DevOps team runs several production Amazon RDS for PostgreSQL instances that do NOT have storage autoscaling enabled (a legacy requirement mandates fixed allocated storage). Nightly batch jobs occasionally cause free storage to drop dangerously low, and by the time the on-call engineer responds, the database has entered a storage-full state. The team wants a fully automated response that, when free storage crosses a low threshold, immediately increases the instance's allocated storage by a fixed increment and posts a notification to a Slack channel — without any human in the loop. Which implementation best meets these requirements?

Accepted Answer

Create a CloudWatch alarm on the FreeStorageSpace metric for each instance. Configure the alarm to trigger an EventBridge rule matching the alarm state change to ALARM, which invokes an SSM Automation runbook that calls modify-db-instance to increase AllocatedStorage and then publishes to an SNS topic subscribed by an AWS Chatbot Slack channel.

Answer

Enable RDS storage autoscaling on each instance and set the maximum storage threshold, then create an EventBridge rule on the RDS storage autoscaling event to notify Slack via SNS.

Answer

Create an EventBridge scheduled rule that runs every 5 minutes and invokes a Lambda function which describes each instance's storage and calls modify-db-instance when needed, notifying Slack through an API destination.

Answer

Configure an RDS event subscription for the 'low storage' event category routed to an SNS topic, and subscribe a Lambda function that increases allocated storage and posts to Slack.