tree: 9335f703888cbed894bb1eac37ff2a1abf7ce200 [path history] [tgz]
  1. app/
  2. meta/
  3. system-metrics/
  4. testapp/
  5. testing/
  6. utils/



Cobalt is a system for collecting metrics from Fuchsia devices, sending metric observations to servers running in the cloud, aggregating and analyzing the collected observations and generating useful reports and visualizations. Cobalt emphasizes the preservation of user privacy while collecting high-quality, useful analytics.


  • Customer and Project. Cobalt is a multi-tenant system. We partition the system using the notions of customer and project. For example Fuchsia is a customer and Ledger is a project.
  • Metric: A variable to be measured, e.g. the number of times that a Fuchsia device was booted.
  • Observation: A single measurement of a metric, e.g. “This Fuchsia device has booted.” Observations are the units of data transmitted from the client running Fuchsia to the Cobalt servers.
  • Encoding: A built-in algorithm for encoding Observations. Some of Cobalt's encodings implement special privacy-preserving algorithms.

FIDL Protocol

Fuchsia code uses Cobalt through its FIDL protocol. See //sdk/fidl/fuchsia.cobalt/cobalt.fidl.

Cobalt Test App

The Cobalt test app serves as an example usage of the Cobalt FIDL service.

Building the test app:

For example:

$ fx set x64
$ fx full-build

Running the test app:

Start Fuchsia. For example:

$ fx emu -N

From within Fuchsia:

$ system/test/cobalt_testapp

or try

$ system/test/cobalt_testapp --verbose=3