Attaches the telemetry handler to the given event.

Available options

• :level - log level which is used to log requests. Defaults to :info.

Dynamic log level

In some cases you may wish to set the log level dynamically on a per-query basis. To do so, set the :level option to a tuple, {Mod, Fun, Args}. The query and map of time measures will be prepended to the provided list of arguments.

When invoked, your function must return a Logger.level() or false to disable logging for the request.

Examples

Attaching the telemetry handler to the MyApp.Repo events with the :info log level:

# in the endpoint
plug Plug.Telemetry, event_prefix: [:myapp, :plug]

# in your application.ex
LoggerJSON.Plug.attach("logger-json-requests", [:myapp, :plug, :stop], :info)

To make plug broadcast those events see Plug.Telemetry documentation.

You can also attach to the [:phoenix, :endpoint, :stop] event to log request latency from Phoenix endpoints:

LoggerJSON.Plug.attach("logger-json-phoenix-requests", [:phoenix, :endpoint, :stop], :info)

@spec telemetry_logging_handler(
  event_name :: [atom()],
  query_time :: %{duration: non_neg_integer()},
  metadata :: %{conn: Plug.Conn.t()},
  level ::
    Logger.level()
    | {module :: module(), function :: atom(), arguments :: [term()]}
    | false
) :: :ok

A telemetry handler that logs requests in a structured format.