Phoenix.Logger (Phoenix v1.7.20)

Instrumenter to handle logging of various instrumentation events.

Instrumentation

Phoenix uses the :telemetry library for instrumentation. The following events are published by Phoenix with the following measurements and metadata:

• [:phoenix, :endpoint, :init] - dispatched by Phoenix.Endpoint after your Endpoint supervision tree successfully starts

  • Measurement: %{system_time: system_time}
  • Metadata: %{pid: pid(), config: Keyword.t(), module: module(), otp_app: atom()}
  • Disable logging: This event is not logged

• [:phoenix, :endpoint, :start] - dispatched by Plug.Telemetry in your endpoint, usually after code reloading

  • Measurement: %{system_time: system_time}
  • Metadata: %{conn: Plug.Conn.t, options: Keyword.t}

  • Options: %{log: Logger.level | false}

  • Disable logging: In your endpoint plug Plug.Telemetry, ..., log: Logger.level | false

  • Configure log level dynamically: plug Plug.Telemetry, ..., log: {Mod, Fun, Args}

• [:phoenix, :endpoint, :stop] - dispatched by Plug.Telemetry in your endpoint whenever the response is sent

  • Measurement: %{duration: native_time}
  • Metadata: %{conn: Plug.Conn.t, options: Keyword.t}

  • Options: %{log: Logger.level | false}

  • Disable logging: In your endpoint plug Plug.Telemetry, ..., log: Logger.level | false

  • Configure log level dynamically: plug Plug.Telemetry, ..., log: {Mod, Fun, Args}

• [:phoenix, :router_dispatch, :start] - dispatched by Phoenix.Router before dispatching to a matched route

  • Measurement: %{system_time: System.system_time}

  • Metadata: %{conn: Plug.Conn.t, route: binary, plug: module, plug_opts: term, path_params: map, pipe_through: [atom], log: Logger.level | false}

  • Disable logging: Pass log: false to the router macro, for example: get("/page", PageController, :index, log: false)
  • Configure log level dynamically: get("/page", PageController, :index, log: {Mod, Fun, Args})

• [:phoenix, :router_dispatch, :exception] - dispatched by Phoenix.Router after exceptions on dispatching a route

  • Measurement: %{duration: native_time}

  • Metadata: %{conn: Plug.Conn.t, kind: :throw | :error | :exit, reason: term(), stacktrace: Exception.stacktrace()}

  • Disable logging: This event is not logged

• [:phoenix, :router_dispatch, :stop] - dispatched by Phoenix.Router after successfully dispatching a matched route

  • Measurement: %{duration: native_time}

  • Metadata: %{conn: Plug.Conn.t, route: binary, plug: module, plug_opts: term, path_params: map, pipe_through: [atom], log: Logger.level | false}

  • Disable logging: This event is not logged

• [:phoenix, :error_rendered] - dispatched at the end of an error view being rendered

  • Measurement: %{duration: native_time}
  • Metadata: %{conn: Plug.Conn.t, status: Plug.Conn.status, kind: Exception.kind, reason: term, stacktrace: Exception.stacktrace}
  • Disable logging: Set render_errors: [log: false] on your endpoint configuration

• [:phoenix, :socket_connected] - dispatched by Phoenix.Socket, at the end of a socket connection

  • Measurement: %{duration: native_time}

  • Metadata: %{endpoint: atom, transport: atom, params: term, connect_info: map, vsn: binary, user_socket: atom, result: :ok | :error, serializer: atom, log: Logger.level | false}

  • Disable logging: use Phoenix.Socket, log: false or socket "/foo", MySocket, websocket: [log: false] in your endpoint

• [:phoenix, :socket_drain] - dispatched by Phoenix.Socket when using the :drainer option

  • Measurement: %{count: integer, total: integer, index: integer, rounds: integer}

  • Metadata: %{endpoint: atom, socket: atom, intervasl: integer, log: Logger.level | false}

  • Disable logging: use Phoenix.Socket, log: false in your endpoint or pass :log option in the :drainer option

• [:phoenix, :channel_joined] - dispatched at the end of a channel join

  • Measurement: %{duration: native_time}

  • Metadata: %{result: :ok | :error, params: term, socket: Phoenix.Socket.t}

  • Disable logging: This event cannot be disabled

• [:phoenix, :channel_handled_in] - dispatched at the end of a channel handle in

  • Measurement: %{duration: native_time}
  • Metadata: %{event: binary, params: term, socket: Phoenix.Socket.t}
  • Disable logging: This event cannot be disabled

To see an example of how Phoenix LiveDashboard uses these events to create metrics, visit https://hexdocs.pm/phoenix_live_dashboard/metrics.html.

Parameter filtering

When logging parameters, Phoenix can filter out sensitive parameters such as passwords and tokens. Parameters to be filtered can be added via the :filter_parameters option:

config :phoenix, :filter_parameters, ["password", "secret"]

With the configuration above, Phoenix will filter any parameter that contains the terms password or secret. The match is case sensitive.

Phoenix's default is ["password"].

Phoenix can filter all parameters by default and selectively keep parameters. This can be configured like so:

config :phoenix, :filter_parameters, {:keep, ["id", "order"]}

With the configuration above, Phoenix will filter all parameters, except those that match exactly id or order. If a kept parameter matches, all parameters nested under that one will also be kept.

Dynamic log level

In some cases you may wish to set the log level dynamically on a per-request basis. To do so, set the :log option to a tuple, {Mod, Fun, Args}. The Plug.Conn.t() for the request 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.

For example, in your Endpoint you might do something like this:

  # lib/my_app_web/endpoint.ex
  plug Plug.Telemetry,
    event_prefix: [:phoenix, :endpoint],
    log: {__MODULE__, :log_level, []}

  # Disables logging for routes like /status/*
  def log_level(%{path_info: ["status" | _]}), do: false
  def log_level(_), do: :info

Disabling

When you are using custom logging system it is not always desirable to enable Phoenix.Logger by default. You can always disable this in general by:

config :phoenix, :logger, false