Telemetry

What you'll learn in this chapter

  • Ground rules of telemetry, privacy, opt-in

  • Basics of Clear Linux OS telemetry

  • Creating a custom telemetry event

  • Backend collection concepts

Concepts

Clear Linux OS uses a lightweight telemetry solution to allow applications to avoid being concerned with transporting the data and whether a user has opted in or out. The solution can provide near real time data to improve applications.

Because software updates in Clear Linux OS are performed automatically, it is important that application developers leverage telemetry where appropriate. Traditional QA testing and functional testing are often incomplete. The Clear Linux OS telemetry solution bridges that gap and helps developers monitor their applications.

By default, telemetry isn't opt-out and the installer will ask people if telemetry should be enabled, with the default selection being "not enabled". We do encourage people to enable telemetry to help out and make Clear Linux OS higher quality.

Intel's privacy policies are applicable to the Clear Linux OS telemetry stack, and the Clear Linux OS telemetry does not collect intentionally identifiable information about the user or system owner. People who use the telemetry APIs discussed in this chapter must ensure that their use does not conflict with any Intel policies or local privacy laws.

The telemetry API revolves around the delivery of telemetry records as an individual unit to a HTTPS collection service. On the client, a spooling daemon telemd takes care of opt-in/out, throttling, and encapsulating the telemetry data. Several telemetry probes generate probe specific payload data and deliver it to the telemd service for delivery.

How to start

First, we enable telemetry on the target device. For this, we add the telemetrics bundle to our mix, and make it available to clients.

~/mix $ mixer bundle add telemetrics
Adding bundle "telemetrics" from upstream bundles
~/mix $ sudo mixer build all

We can modify the image to add telemetry by default as a bundle, but we would lose our existing system. We add it on our target device manually for now:

~ # swupd update
~ # swupd bundle-add telemetrics

Essentially, we now have everything to create telemetry events, even from C programs or Python* if needed, because the telemetry bundle provides a simple pipe-based CLI program that can be called trivially:

~ # telem-record-gen --help
Usage:
  telem-record-gen [OPTIONS] - create and send a custom telemetry record

Help Options:
  -h, --help            Show help options

Application Options:
  -f, --config-file     Path to configuration file (not implemented yet)
  -V, --version         Print the program version
  -s, --severity        Severity level (1-4) - (default 1)
  -c, --class           Classification level_1/level_2/level_3
  -p, --payload         Record body (max size = 8k)
  -P, --payload-file    File to read payload from
  -R, --record-version  Version number for format of payload (default 1)
  -e, --event-id        Event id to use in the record

Using the C library (libtelemetry.so - man 3 telemetry) uses the exact same API parameters and yields the same effect.

Let's try generating a simple heartbeat event, similar to the hprobe heartbeat probe that Clear Linux OS includes by default.

~ # telem-record-gen -c org.clearlinux/hello/world -p "hello"

We won't see anything happen, but we can track existing and previous telemetry events with telemctl:

~ # telemctl journal

A full example of the heartbeat probe in C is documented in the source code here:

Pointing telemetry to a custom backend

If you have a functional custom collector, you can modify where your telemetry records get sent by modifying /etc/telemetrics/telemetrics.conf and changing the server value to point to the new telemetry collection URL. Setting up a custom collector is not covered in this training.

If you are deploying a custom backend for many Clear Linux OS installations, you may want to patch the system wide default /usr/share/defaults/telemetrics/telemetrics.conf file to include a custom collection URL built into the binary.

Further reading

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