Glean is a modern approach for recording and sending Telemetry data.
It's in use at Mozilla.
All documentation can be found online:
A module containing glean-core code for supporting data migration (i.e. sequence numbers) from glean-ac. This is a temporary module planned to be removed in 2020, after the transition from glean-ac is complete.
The different metric types supported by the Glean SDK to handle data.
Ping collection, assembly & submission.
The common set of data shared across all different metric types.
The Glean configuration.
The object holding meta information about a Glean instance.
The possible error types for metric recording.
The supported metrics' lifetimes.
Get the number of recorded errors for the given metric and error type.