Req plugin to instrument requests with :telemetry events.

Usage

Preferably, ReqTelemetry should be the last plugin attached to your %Req.Request{}. This allows ReqTelemetry to emit events both at the very start and very end of the request and response pipelines. In this way, you can observe both the total time spent issuing and processing the request and response, as well as the time spent only with the request adapter.

req = Req.new() |> ReqTelemetry.attach()

req =
  Req.new(adapter: &my_adapter/1)
  |> ReqSomeOtherThing.attach()
  |> ReqTelemetry.attach()

Events

ReqTelemetry produces the following events (in order of event dispatch):

• [:req, :request, :pipeline, :start]
• [:req, :request, :adapter, :start]
• [:req, :request, :adapter, :stop]
• [:req, :request, :adapter, :error]
• [:req, :request, :pipeline, :stop]
• [:req, :request, :pipeline, :error]

You can configure ReqTelemetry to produce only :pipeline or :adapter events; see ReqTelemetry.attach/2 for options.

Logging

ReqTelemetry defines a a simple, default logger that logs basic request information and timing.

Here's how a successful request might be logged:

Req:479128347 - GET https://example.org (pipeline)
Req:479128347 - GET https://example.org (adapter)
Req:479128347 - 200 in 403ms (adapter)
Req:479128347 - 200 in 413ms (pipeline)

For usage and configuration, see ReqTelemetry.attach_default_logger/1.

Installation

req_telemetry is available through hex.pm, and can be installed by adding the following to your list of dependencies:

def deps do
  [
    {:req_telemetry, "~> 0.1.0"}
  ]
end