View Source Nerves.Runtime.Heart (nerves_runtime v0.13.1)
Functions for querying Nerves Heart and the device's watchdog
Nerves Heart integrates Erlang's
heart process with a hardware
watchdog. This makes it possible for a device to recover from a hang. The
way it works is that the Erlang runtime regularly checks that it's ok. If so,
it sends a message to heart. Nerves heart then pets the hardware watchdog.
If messages ever stop being sent to heart, the hardware watchdog will trip
and reboot the device. You can add additional health checks for your
application by providing a callback to :heart.set_callback/2.
Link to this section Summary
Functions
Return whether Nerves heart is running
Raising version of status/0
Return the current Nerves Heart status
Link to this section Types
@type info() :: %{ program_name: String.t(), program_version: Version.t(), identity: String.t(), firmware_version: non_neg_integer(), options: non_neg_integer() | [atom()], time_left: non_neg_integer(), pre_timeout: non_neg_integer(), timeout: non_neg_integer(), last_boot: :power_on | :watchdog, heartbeat_timeout: non_neg_integer() }
Nerves Heart's current status
:program_name-"nerves_heart":program_version- Nerves heart's version number:identity- The hardware watchdog that's being used:firmware_version- An integer that represents the hardware watchdog's firmware revision:options- Hardware watchdog options as reported by Linux:time_left- How many seconds are left before the hardware watchdog triggers a reboot:pre_timeout- How many seconds before the watchdog expires that Linux will receive a pre-timeout notification:timeout- The hardware watchdog timeout. This is only changeable in the Linux configuration:last_boot- What caused the most recent boot. Whether this is reliable depends on the watchdog.:heartbeat_timeout- Erlang's heartbeat timeout setting. Note that the hardware watchdog timeout supersedes this since it reboots.
Link to this section Functions
@spec running?() :: boolean()
Return whether Nerves heart is running
If you're using a Nerves device, this always returns true except possibly
when porting Nerves to new hardware. It is a quick sanity check.
@spec status!() :: info()
Raising version of status/0
@spec status() :: {:ok, info()} | :error
Return the current Nerves Heart status
Errors are returned when not running Nerves Heart