RDS Instance Scheduling
CostLens detects non-production RDS instances running 24/7 and recommends scheduling them to stop outside business hours.
RDS instances for development, staging, and test environments typically don't need to run on weekends or overnight. CostLens identifies single-AZ RDS instances that are running around the clock and recommends scheduling them to stop outside business hours — saving up to 70% of the instance cost.
How it works
CostLens scans for running single-AZ instances
Identifies RDS instances in the "available" state. Multi-AZ instances are excluded — AWS does not allow them to be stopped.
Filters out production instances
Instances tagged Environment=production or with "prod" in the name are automatically excluded.
Calculates potential savings
Compares the cost of running 730 hours/month (24/7) against 216 hours/month (Mon–Fri, 08:00–18:00 UTC), and estimates approximately 70% savings.
Applies schedule on fix
Creates EventBridge rules to stop and start the instance on the configured schedule.
Configuring the schedule
When you click Apply Fix, CostLens prompts you to configure the schedule:
| Setting | Default | Options |
|---|---|---|
| Weekday start | 08:00 UTC | Any time |
| Weekday stop | 18:00 UTC | Any time |
| Days | Mon–Fri | Any combination |
| Weekend behaviour | Off | Off / Same as weekday hours |
The schedule is applied by tagging the instance with AezonaCostlens:RDSSchedule and creating two EventBridge rules — one to start and one to stop the instance.
Estimated savings
| Instance class | On-Demand monthly cost | Scheduled monthly cost | Monthly saving |
|---|---|---|---|
| db.t3.micro | ~$12 | ~$4 | ~$8 |
| db.t3.medium | ~$49 | ~$15 | ~$34 |
| db.m5.large | ~$125 | ~$37 | ~$88 |
| db.r5.large | ~$175 | ~$52 | ~$123 |
Removing a schedule
To remove an existing schedule and let the instance run 24/7 again:
- Delete the two EventBridge rules created by CostLens (named
CostLens-Start-{db-id}andCostLens-Stop-{db-id}). - Remove the
AezonaCostlens:RDSScheduletag from the instance. - Start the instance manually if it is currently stopped.
Severity levels
| Severity | Estimated monthly savings |
|---|---|
| critical | >$500 |
| high | $100–$500 |
| medium | $20–$100 |
| low | <$20 |
Required IAM permissions
Included in the CostLens IAM policies from AWS Accounts:
rds:DescribeDBInstances
rds:StartDBInstance
rds:StopDBInstance
rds:AddTagsToResource
events:PutRule
events:PutTargets
Limitations
- Multi-AZ instances cannot be stopped. AWS does not support stopping Multi-AZ RDS instances — only single-AZ instances are eligible.
- AWS auto-restarts stopped instances after 7 days. The EventBridge schedule ensures the instance is restarted before this 7-day limit is reached.
- Aurora clusters are not included in this check — use AWS Aurora Auto Pause for Aurora Serverless v2.