System Log


The system_log integration stores information about all logged errors and warnings in Home Assistant. All collected information is accessible directly in the frontend, just navigate to the Info section under Developer Tools. In order to not overload Home Assistant with log data, only the 50 last errors and warnings will be stored. Older entries are automatically discarded from the log. It is possible to change the number of stored log entries using the parameter max_entries.

Configuration

This integration is automatically loaded by the frontend (so no need to do anything if you are using the frontend). If you are not doing so, or if you wish to change a parameter, add the following section to your configuration.yaml file:

system_log:
  max_entries: MAX_ENTRIES

Configuration Variables

max_entries

(integer)(Optional)

Number of entries to store (older entries are discarded).

Default value:

50

fire_event

(string)(Optional)

Whether events are fired (required when used for triggers).

Default value:

false

Services

Service clear

To manually clear the system log, call this service.

Service write

Write a log entry

Service data attribute Optional Description
message no Message to log
level yes Log level: debug, info, warning, error, critical. Defaults to ‘error’.
logger yes Logger name under which to log the message. Defaults to ‘system_log.external’.

Events

Errors and warnings are posted as the event system_log_event, so it is possible to write automations that trigger whenever a warning or error occurs. The following information is included in each event:

| Field | Description | |—————————————————————————————––| | level | Either WARNING or ERROR depending on severity. | | source | File that triggered the error, e.g., core.py or media_player/yamaha.py. | | exception | Full stack trace if available, an empty string otherwise. | | message | Descriptive message of the error, e.g., “Error handling request”. | | timestamp | Unix timestamp with as a double, e.g., 1517241010.237416. |

Live examples of these events can be found in the Home Assistant log file (home-assistant.log) or by just looking in the system log. An example could, for instance, look like this:

2019-02-14 16:20:35 ERROR (MainThread) [homeassistant.loader] Unable to find integration system_healt
2019-02-14 16:20:36 ERROR (MainThread) [homeassistant.components.device_tracker] Error setting up platform google_maps
Traceback (most recent call last):
  File "/home/fab/Documents/repos/ha/home-assistant/homeassistant/integrations/device_tracker/__init__.py", line 184, in
[...]

The message (“Unable to find integration system_healt”), source (homeassistant.loader) and level (ERROR) can easily be extracted from the log. The exact timestamp and if there is a stack trace that’s shown as well. Here is another error caused by the google_map integration with additional output present.

Examples

Here are some examples using the events posted by system_log. fire_event must be set to true for these to work.

Counting Number of Warnings

This will create a counter that increases every time a warning is logged:

counter:
  warning_counter:
    name: Warnings
    icon: mdi:alert

automation:
  - alias: Count warnings
    trigger:
      platform: event
      event_type: system_log_event
      event_data:
        level: WARNING
    action:
      service: counter.increment
      entity_id: counter.warning_counter

Conditional Messages

This automation will create a persistent notification whenever an error or warning is logged that has the word “service” in the message:

automation:
  - alias: Create notifications for "service" errors
    trigger:
      platform: event
      event_type: system_log_event
    condition:
      condition: template
      value_template: '{{ "service" in trigger.event.data.message }}'
    action:
      service: persistent_notification.create
      data_template:
        title: Something bad happened
        message: '{{ trigger.event.data.message }}'

Writing to log

This automation will create a new log entry when the door is opened:

automation:
  - alias: Log door opened
    trigger:
      platform: state
      entity_id: binary_sensor.door
      from: 'off'
      to: 'on'
    action:
      service: system_log.write
      data_template:
        message: 'Door opened!'
        level: info