Phoenix instrumenter generator for Prometheus. Implemented as Phoenix instrumenter.

Usage

1. Define your instrumenter:

defmodule MyApp.Endpoint.Instrumenter do
  use Prometheus.PhoenixInstrumenter
end

2. Call MyApp.Endpoint.Instrumenter.setup/0 when application starts (e.g. supervisor setup):

MyApp.Endpoint.Instrumenter.setup()

3. Add MyApp.Endpoint.Instrumenter to Phoenix endpoint instrumenters list:

config :myapp, MyApp.Endpoint,
  ...
  instrumenters: [MyApp.Endpoint.Instrumenter]
  ...

Metrics

Metrics implemented for the following built-in events:

• phoenix_controller_call

  • phoenix_controller_call_duration_<duration_unit>;

• phoenix_controller_render

  • phoenix_controller_render_duration_<duration_unit>;

• phoenix_channel_join

  • phoenix_channel_join_duration_<duration_unit>;

• phoenix_channel_receive

  • phoenix_channel_receive_duration_<duration_unit>.

Predefined controller call labels:

• action - action name (default);
• controller - controller module name (default).

Predefined controller render labels:

• format - name of the format of the template (default);
• template - name of the template (default);
• view - name of the view (default).

Predefined channel join/receive labels:

• channel - current channel module (default);
• endpoint - endpoint module where this socket originated;
• handler - socket module where this socket originated;
• pubsub_server - registered name of the socket’s pubsub server;
• serializer - serializer for socket messages;
• topic - string topic (default);
• transport - socket’s transport;
• transport_name - socket’s transport (default);
• vsn - protocol version of the client (default).

Predefined channel receive labels:

• event - event name (default).

Predefined common http request labels:

• host - request host;
• method - request method;
• port - request port;
• scheme - request scheme.

Predefined compile metadata labels:

• application - name of OTP application;
• file - name of file where instrumented function resides;
• function - name of the instrumented function;
• line - source line number;
• module - instrumented function’s module.

Configuration

Instrumenter configured via :prometheus application environment MyApp.Endpoint.Instrumenter key (i.e. app env key is the name of the instrumenter).

Default configuration:

config :prometheus, MyApp.Endpoint.Instrumenter,
  controller_call_labels: [:controller, :action],
  duration_buckets: :prometheus_http.microseconds_duration_buckets(),
  registry: :default,
  duration_unit: :microseconds

Available duration units:

• microseconds;
• milliseconds;
• seconds;
• minutes;
• hours;
• days.

Bear in mind that buckets are so if you are not using default unit you also have to override buckets.

Custom Labels

Custom labels can be defined by implementing label_value/2 function in instrumenter directly or by calling exported function from other module.

  controller_call_labels: [:controller,
                           :my_private_label,
                           {:label_from_other_module, Module}, # eqv to {Module, label_value}
                           {:non_default_label_value, {Module, custom_fun}}]

defmodule MyApp.Endpoint.Instrumenter do
  use Prometheus.PhoenixInstrumenter

  label_value(:my_private_label, conn) do
    ...
  end
end