Telemetry integration for the railsr client.

Every HTTP call emits three events:

Event Measurements

:start

%{system_time: integer()}

:stop

%{duration: integer(), status: integer()}

:exception

%{duration: integer()}

Event Metadata

All events carry:

%{
  method: atom(),          # :get | :post | :put | :patch | :delete
  path: String.t(),        # "/v1/customer/ledgers"
  attempt: non_neg_integer(),
  library: :railsr
}

Attaching Metrics (Telemetry.Metrics)

# In your application's telemetry setup:
import Telemetry.Metrics

def metrics do
  [
    counter("railsr.request.stop.count", tags: [:method, :path]),
    summary("railsr.request.stop.duration",
      unit: {:native, :millisecond},
      tags: [:method, :path]
    ),
    counter("railsr.request.stop.error_count",
      keep: &match?(%{status: s} when s >= 400, &1),
      tags: [:method, :path]
    )
  ]
end