Lambda Warmer Stack
CloudFormation: EventBridge rules pinging configured Lambda functions every 5 minutes to eliminate cold starts. Configurable function list via parameter.
Lambda Warmer Stack — Kill Cold Starts
Cold starts hurt user experience. This CloudFormation stack deploys a dedicated warmer Lambda that pings your functions every 5 minutes via EventBridge, keeping them hot and ready for real traffic.
What's Included
- Warmer Lambda function (Node.js 22) invoking all target functions in parallel
- EventBridge schedule rule firing every 5 minutes
- Support for up to 10 Lambda function ARNs via a comma-separated parameter
- Warm-up event marker so target functions can short-circuit instantly
- IAM role scoped to the configured function ARNs
Developer Experience
Pass your function ARNs as a CloudFormation parameter and deploy. Target functions receive an event with __warmupEvent: true — add a two-line check to return immediately. Code examples for Node.js, Python, and Go in the README.
What You Get
Measurable cold start reduction for any Lambda runtime. Costs roughly $1–2/month for up to 10 functions. Works across regions.
Requirements
AWS CLI v2 with CloudFormation, Lambda, EventBridge, and IAM permissions. Target function ARNs must be in the same account and region.