tower_opentelemetry 🗼🔭

A Tower reporter that records captured exceptions as OpenTelemetry span events, following the OTEL semantic conventions for exceptions.

Tower is responsible for capturing errors from Plug, Phoenix, Bandit/Cowboy, Oban, LiveView and the Erlang :logger. This package is one of the reporters you can plug in — it forwards every captured event into the active OpenTelemetry trace, so you can ship your application's exceptions to any OTEL-compatible backend (Honeycomb, Datadog, Grafana Tempo, Jaeger, …) without a vendor-specific SDK. 🚀

📦 Installation

def deps do
  [
    {:tower, "~> 0.8"},
    {:tower_opentelemetry, "~> 0.1"}
  ]
end

⚙️ Configuration

# config/config.exs
config :tower, reporters: [TowerOpentelemetry]

You can combine it with other reporters during a migration:

config :tower, reporters: [Tower.Sentry, TowerOpentelemetry]

🏷️ Recorded attributes

Per the OTEL semantic conventions for exceptions, the following attributes are attached to each exception span event:

Attribute	Source
`exception.type`	exception module (or `Exit`/`Throw`/`Message`)
`exception.message`	`Exception.message/1`, otherwise `inspect/1` of `reason`
`exception.stacktrace`	`Exception.format_stacktrace/1`

The reporter also attaches event.id, event.kind and event.level so you can correlate OTEL spans with Tower's normalized event stream. 🔗

👻 Behaviour when no span is active

Tower can capture errors from contexts where there is no active OTEL span (for example, a crash in a background process). In that case, a short-lived span named tower.event is started so the event still reaches the OTEL pipeline.

🗺️ Roadmap

The current OTEL semantic conventions recommend recording exceptions as log records rather than span events. Once the Erlang OpenTelemetry SDK ships a stable logs API on Hex, this reporter will gain a mode: :logs option and follow the spec's OTEL_SEMCONV_EXCEPTION_SIGNAL_OPT_IN migration path.

📄 License

MIT — see LICENSE.