Function observability
Inspect function invocations, cold starts, duration, and billing fields.
Function observability explains how Easel executes server-side code for a deployment.
Use Observability charts for trends, Logs for per-request compute fields, and Invocations when one function wake served multiple HTTP requests.
Invocations
One function invocation (wake) can serve more than one HTTP request when the runtime keeps the isolate warm and multiplexes traffic.
Invocations lists those wakes with columns such as:
- Route
- Request count (Reqs)
- Cold start
- Duration
- Compute
- AWS duration and AWS billed
- Init
- Memory
- Instance
Select an invocation to open:
- Overview: summary metrics and a waterfall of requests served on that wake
- Trace: an invocation-level Trace focused on lifecycle and per-request summary bars
Use Open in Logs to jump to the request list for the same invocation ID.
Duration fields
Different duration values measure different things:
| Field | Meaning |
|---|---|
| Duration (Invocations) | Wall time for the wake |
| Compute duration | Customer function work through response body completion |
| Post-response | Work after the response finishes (waitUntil, flush) |
| AWS duration | Duration reported by the Lambda Telemetry API for the wake |
| AWS billed | Billed duration reported for the wake |
| AWS init / Init | Initialization time when the wake was cold |
Do not use “duration” without checking which field you mean. Request Trace spans show where time went inside one HTTP request; AWS billed and cold start remain on request detail and Invocations.
Cold and warm starts
- Cold: the wake initialized a new runtime process.
- Warm: the wake reused an existing process.
Observability Function Starts charts break volume into cold and warm. Easel does not use a separate “hot” product term.
Memory and instance
Invocations can show configured memory and maximum memory used for the wake, plus an Instance identifier for the underlying compute process.
Function region for compute is typically iad (US East). See
Function regions.
Errors and timeouts
Failed requests appear with 5xx statuses in Logs and error series on Observability charts. Investigate with request detail, function log lines, and Trace spans.
Application timeouts follow your route maxDuration and platform limits. See
Function limits.