Telemetry, in error monitoring, is the ordered trail of events an SDK records in the seconds before an error and ships attached to it, so you can see what the application was doing when it failed. The individual events are usually called breadcrumbs.
A stack trace tells you which line threw. Telemetry tells you that the request behind that line returned a 500 four hundred milliseconds earlier.
Example
A browser telemetry timeline leading into an error:
14:22:07.113 navigation /invoices -> /invoices/8821
14:22:07.480 network GET /api/invoices/8821 500
14:22:07.484 console warn: "invoice payload missing amount"
14:22:07.491 dom click button#retry
14:22:07.502 error TypeError: Cannot read properties of null
What Rollbar does with telemetry
Rollbar captures telemetry in its JavaScript, iOS and .NET SDKs and renders it as a timeline on the occurrence, with the occurrence itself as the final entry. In the browser Rollbar instruments five event types by default: network requests including method, URL and response code; console calls; DOM clicks and inputs; route navigation; and connectivity changes. Rollbar holds the most recent 100 events in a fixed FIFO queue and sends them with the item, and you control which types are captured with autoInstrument and the queue length with maxTelemetryEvents.
Rollbar never records the value of a password input, and scrubs any input whose name matches your configured scrub fields. Set scrubTelemetryInputs: true to drop every input value, or supply a telemetryScrubber function for per-element control.
Related terms
Sources
- Rollbar Docs, Telemetry: https://docs.rollbar.com/docs/telemetry
- Rollbar Docs, JavaScript Telemetry: https://docs.rollbar.com/docs/rollbarjs-telemetry
