The baseline ping


This ping is intended to provide metrics that are managed by the library itself, and not explicitly set by the application or included in the application's metrics.yaml file. If the application crashes no baseline ping is sent, no additional ping is generated with the data from before the crash.


The baseline ping is automatically sent when the application is moved to the background.


The baseline ping includes the following fields:

Field nameTypeDescription
durationTimespanThe duration, in seconds, of the last foreground session
localeStringThe locale of the application

The baseline ping shall also include the common ping sections found in all pings.

Querying ping contents

A quick note about querying ping contents (i.e. for Each metric in the baseline ping is organized by its metric type, and uses a namespace of glean.baseline. For instance, in order to select duration you would use metrics.timespan['glean.baseline.duration']. If you were trying to select a String based metric such as os, then you would use metrics.string['glean.baseline.os']

Example baseline ping

  "ping_info": {
    "ping_type": "baseline",
    "experiments": {
      "third_party_library": {
        "branch": "enabled"
    "seq": 0,
    "start_time": "2019-03-29T09:50-04:00",
    "end_time": "2019-03-29T09:53-04:00"
  "client_info": {
    "telemetry_sdk_build": "0.49.0",
    "first_run_date": "2019-03-29-04:00",
    "os": "Android",
    "android_sdk_version": "27",
    "os_version": "8.1.0",
    "device_manufacturer": "Google",
    "device_model": "Android SDK built for x86",
    "architecture": "x86",
    "app_build": "1",
    "app_display_version": "1.0",
    "client_id": "35dab852-74db-43f4-8aa0-88884211e545"
  "metrics": {
    "string": {
      "glean.baseline.locale": "en-US"
    "timespan": {
      "glean.baseline.duration": {
        "value": 52,
        "time_unit": "second"