howdy_telemetry

OpenTelemetry for howdy apps. Howdy opens spans with howdy/trace around requests, database queries, remote calls, email and sign-in; this package is what sends them somewhere. Without it, or until telemetry.start is called, nothing is recorded or sent.

gleam add howdy_telemetry@1

Production

import howdy/telemetry

let assert Ok(Nil) =
  telemetry.new("acme-web")
  |> telemetry.otlp
  |> telemetry.sample(0.25)
  |> telemetry.start

otlp sends spans over OTLP/HTTP to OTEL_EXPORTER_OTLP_ENDPOINT (http://localhost:4318 by default) with OTEL_EXPORTER_OTLP_HEADERS, so it works with an OpenTelemetry collector, Grafana Tempo, Honeycomb, Jaeger and the rest. telemetry.from_env(service) gives a configuration only when an endpoint is set. json_logs writes logs as JSON with trace ids.

Development

let recorder = recorder.new(keep: 200)
let assert Ok(Nil) =
  telemetry.new("acme-web") |> telemetry.record(recorder) |> telemetry.start
admin.new() |> admin.telemetry(recorder)

The admin then shows each request as a timeline of its queries, calls, emails and logs, and points out statements that run once per row.

How it works

The OpenTelemetry SDK is an OTP application, so it starts when the app boots, with defaults that would export to localhost:4318. This package’s own application replaces that at boot with the API’s no-op tracer, so installing it changes nothing; start then installs a tracer provider built from the configuration. The recorder is a span processor that keeps finished spans in ETS tables.

See the docs for more.