The baseline ping


This ping is intended to provide metrics that are managed by the Glean SDKs themselves, and not explicitly set by the application or included in the application's metrics.yaml file.

Platform availability

SDKKotlinSwiftPythonRustJavaScriptFirefox Desktop
baseline ping


The baseline ping is automatically submitted with a reason: active when the application becomes active (on mobile it means getting to foreground). These baseline pings do not contain duration.

The baseline ping is automatically submitted with a reason: inactive when the application becomes inactive (on mobile it means getting to background). If no baseline ping is triggered when becoming inactive (e.g. the process is abruptly killed) a baseline ping with reason dirty_startup will be submitted on the next application startup. This only happens from the second application start onward.

See also the ping schedules and timing overview.


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

It also includes a number of metrics defined in the Glean SDKs themselves.

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": {
    "experiments": {
      "third_party_library": {
        "branch": "enabled"
    "seq": 0,
    "start_time": "2019-03-29T09:50-04:00",
    "end_time": "2019-03-29T09:53-04:00",
    "reason": "foreground"
  "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": {
    "timespan": {
      "glean.baseline.duration": {
        "value": 52,
        "time_unit": "second"