New CloudWatch Cold Start Metrics

[metaskills]

Optional and defaults to being turned off. Use config.cold_start_metrics = true to enable.

https://docs.aws.amazon.com/lambda/latest/dg/troubleshooting-invocation.html#

For functions using unreserved (on-demand) concurrency, Lambda may proactively initialize a function instance, even if there's no invocation. When this happens, you can observe an unexpected time gap between your function's initialization and invocation phases. This gap can appear similar to what you would observe using provisioned concurrency.