matrix/roles/synapse/docs/logging.md

synapse logging configuration

Synapse uses a buffer handler per default, which flushes periodically, but flushes logs immediately for log events with a level greater or equal to WARNING.

To set your desired log level, specify it in synapse_log_config_root_level.

Formatters

By default, the upstream precise formatter is availabe. To define and use more formatters, extend synapse_log_config_formatters like this:

synapse_log_config_formatters_custom_json:
  custom_json:
    format: >-
      {"lineno": %(lineno)d, "level": "%(levelname)s", "req_id": "%(request)s", "msg": "%(message)s"}      
synapse_log_config_formatters: >-2
  {{
    ({ synapse_log_config_formatters_precise_name: synapse_log_config_formatters_precise })
    | combine(synapse_log_config_formatters_custom_json)
  }}

# Set handlers to use your formatter like this
synapse_log_config_handlers_file_formatter: custom_json
synapse_log_config_handlers_console_formatter: custom_json

Handlers

For modifying the built-in file/buffer/console handlers, see the defaults in ../defaults/main/log.config.yml.

Containers

For typical container setups, it is often recommended to log all logs to stdout/stderr. This can be easily archieved by setting synapse_log_config_root_handlers: [ synapse_log_config_handlers_console_name ].

Child loggers

To set a different configuration / log level for child loggers of the root logger (currently, this is only synapse.storage.SQL), override synapse_log_config_loggers directly or for the SQL loggers, set the level in synapse_log_config_loggers_synapse_storage_sql_level (which defaults to synapse_log_config_root_level).