Exporting Telemetry from a Function That Scales to Zero
AWS Lambda forwards everything you write to stdout into CloudWatch for free, and it keeps doing so even after your handler has returned. The moment you want richer signals than text logs, or you want to send them anywhere other than CloudWatch, that free path stops being enough: you have to push the data over the network yourself. On a function that freezes between invocations, every way of doing that trades off against one of two things. You either pay Lambda’s per-millisecond billing for the time spent waiting on a remote endpoint, or you risk dropping the telemetry entirely when the environment is suspended out from under you. This post walks the approaches from simplest to most reliable and names where each one bills you or loses signals. The problem is not specific to CloudWatch; it applies to any serverless environment that scales to zero. ...