Function logs

To find the server, image optimization, and warmer log, go to the AWS CloudWatch console in the region you deployed to.

If the server function is deployed to Lambda@Edge, the logs will appear in the region you are physically close to. For example, if you deployed your app to us-east-1 and you are visiting the app from in London, the logs are likely to be in eu-west-2.

Warmer function logs

The logs from the warmer function provide insights into the results of the warming process.

{ event: 'warmer result', sent: 2, success: 2, uniqueServersWarmed: 2 }
  • sent — The number of times the warmer invoked the server function using the Lambda SDK. This value should correspond to the CONCURRENCY set in the warmer function.
  • success — The number of SDK calls that returned a 200 status code, indicating successful invocations.
  • uniqueServersWarmed — This helps track any instances that responded unusually quickly and served multiple warming requests. As all SDK calls are made concurrently using await Promise.all(), this metric is useful for monitoring the number of unique warmed instances.

Opening an issue

To help diagnose issues, it's always helpful to provide a reproducible setup when opening an issue. One easy way to do this is to create a pull request (PR) and add a new page to the benchmark app located in the example folder, which reproduces the issue. The PR will automatically deploy the app to AWS.