Error Tracking

Gust can asynchronously report terminal task failures without interrupting DAG execution. Implement the Gust.DAG.Run.ErrorReporter behaviour and configure it as the :reporter.

capture/3 runs asynchronously in Gust.DAG.Run.ErrorReporter.Worker. Exceptions, exits, and throws from an adapter are logged and contained so they cannot interrupt DAG execution. When it returns an external reference, the worker adds that reference to the task's persisted error map.

Sentry example

With the :sentry package installed and configured, an adapter can report task errors through Sentry.capture_exception/2:

defmodule MyApp.SentryErrorReporter do
  @behaviour Gust.DAG.Run.ErrorReporter

  @impl true
  def capture(exception, stacktrace, metadata) do
    Sentry.capture_exception(exception, stacktrace: stacktrace, tags: metadata)
    :ok
  end
end

config :gust,
  error_tracking: [reporter: MyApp.SentryErrorReporter]

Custom reporter example

Implement capture/3 in an adapter module and configure it under the :error_tracking application environment:

defmodule MyApp.ErrorReporter do
  @behaviour Gust.DAG.Run.ErrorReporter

  @impl true
  def capture(exception, stacktrace, metadata) do
    response =
      Req.post!("https://errors.example.com/events",
        json: %{
          message: Exception.message(exception),
          stacktrace: Exception.format_stacktrace(stacktrace),
          metadata: metadata
        }
      )

    {:ok, response.body["url"]}
  end
end

config :gust,
  error_tracking: [reporter: MyApp.ErrorReporter]

capture/3 receives the failed task's exception, stacktrace, and metadata (task_id, task_name, run_id, dag_name). It may return :ok, or {:ok, external_url} when the provider exposes an HTTP(S) page for the captured error.

See the Gust.DAG.Run.ErrorReporter module documentation for the full behaviour reference.