Template method for creating Plug to trace your Plug requests.

Usage

1. Create your own Plug module:

  defmodule MyApp.TracingPlug do
    use Opencensus.Plug.Trace
  end

2. Add it to your pipeline, ex. for Phoenix:

  defmodule MyAppWeb.Endpoint do
    use Phoenix.Endpoint, otp_app: :my_app

    plug MyApp.TracingPlug
  end

Configuration

This module creates 2 callback modules, which allows you to configure your span and also provides a way to add custom attributes assigned to span.

• c:span_name/1 - defaults to request path
• c:span_status/1 - defaults to mapping of reponse code to OpenCensus span value, see :opencensus.http_status_to_trace_status/1.

And also you can use attributes argument in use which must be either list of attributes which are names of 1-argument functions in current module that must return string value of the attribute, or map/keyword list of one of:

• atom - which is name of the called function
• {module, function} - which will call apply(module, function, [conn])
• {module, function, args} - which will prepend conn to the given arguments and call apply(module, function, [conn | args])

Example:

defmodule MyAppWeb.TraceWithCustomAttribute do
  use Opencensus.Plug.Trace, attributes: [:method]

  def method(conn), do: conn.method
end