Reference: memfault-device-info

Useful links:

• Reference: memfaultctl CLI.
• Integration Guide: add memfault-device-info.

Purpose of memfault-device-info

memfault-device-info is a program that memfaultd depends on to retrieve static information about the device it is running on. When memfaultd (or memfaultctl) runs, it will execute memfault-device-info and parse the output to collect this information.

As an integrator, you will need to implement this program and make it available on the PATH of the memfaultd process. (By default on Yocto for systemd units, this is /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin).

Implementing memfault-device-info

• When executed, memfault-device-info should print out the device's unique identifier (for example, its serial number) and its Hardware Version in the following format:

  MEMFAULT_DEVICE_ID=<device identifier>
  MEMFAULT_HARDWARE_VERSION=<Hardware Version>

  For example, an output might look like this:

  MEMFAULT_DEVICE_ID=1234-example-serial
  MEMFAULT_HARDWARE_VERSION=thingy-evt2

• The MEMFAULT_DEVICE_ID value should be unique to the device. It should not change over the lifetime of the device. The value must be between 1 and 128 characters long and can only contain the following characters: a-z, A-Z, 0-9, - and _. If MEMFAULT_DEVICE_ID is not set by memfault-device-info, memfaultd will default to the value in /etc/machine-id.

• The MEMFAULT_HARDWARE_VERSION value should be a string that identifies the Hardware Version of the device. It should not change over the lifetime of the device. See this page for more details and examples. If MEMFAULT_HARDWARE_VERSION is not set by memfault-device-info, memfaultd will default to the output of the command uname -n.

From Linux SDK 1.8.0 on, memfault-device-info can also override the following values that are set in memfaultd.conf:

• Software Version: can be set with MEMFAULT_SOFTWARE_VERSION
• Software Type: can be set with MEMFAULT_SOFTWARE_TYPE

Testing

To test whether you have correctly implemented memfault-device-info, you can run memfaultctl show-settings on the device. This will print out the device info that memfaultctl has parsed and collected from memfault-device-info:

$ memfaultctl show-settings

...

Device configuration from memfault-device-info:
  MEMFAULT_DEVICE_ID=1234-example-serial
  MEMFAULT_HARDWARE_VERSION=thingy-evt2

...