defmodule OpentelemetryEcto do @moduledoc """ Telemetry handler for creating OpenTelemetry Spans from Ecto query events. Any relation preloads, which are executed in parallel in separate tasks, will be linked to the span of the process that initiated the call. For example: Tracer.with_span "parent span" do Repo.all(Query.from(User, preload: [:posts, :comments])) end this will create a span called "parent span" with three child spans for each query: users, posts, and comments. > #### Note {: .neutral} > > Due to limitations with how Ecto emits its telemetry, nested preloads are not > represented as nested spans within a trace. """ require OpenTelemetry.Tracer @doc """ Attaches the OpentelemetryEcto handler to your repo events. This should be called from your application behaviour on startup. Example: OpentelemetryEcto.setup([:blog, :repo]) You may also supply the following options in the second argument: * `:time_unit` - a time unit used to convert the values of query phase timings, defaults to `:microsecond`. See `System.convert_time_unit/3` * `:span_prefix` - the first part of the span name, as a `String.t`, defaults to the concatenation of the event name with periods, e.g. `"blog.repo.query"`. This will always be followed with a colon and the source (the table name for SQL adapters). * `:additional_attributes` - additional attributes to include in the span. If there are conflits with default provided attributes, the ones provided with this config will have precedence. """ def setup(event_prefix, config \\ []) do event = event_prefix ++ [:query] :telemetry.attach({__MODULE__, event}, event, &__MODULE__.handle_event/4, config) end @doc false def handle_event( event, measurements, %{query: query, source: source, result: query_result, repo: repo, type: type}, config ) do # Doing all this even if the span isn't sampled so the sampler # could technically use the attributes to decide if it should sample or not total_time = measurements.total_time end_time = :opentelemetry.timestamp() start_time = end_time - total_time database = repo.config()[:database] url = case repo.config()[:url] do nil -> # TODO: add port URI.to_string(%URI{scheme: "ecto", host: repo.config()[:hostname]}) url -> url end span_name = case Keyword.fetch(config, :span_prefix) do {:ok, prefix} -> prefix :error -> Enum.join(event, ".") end <> if source != nil, do: ":#{source}", else: "" time_unit = Keyword.get(config, :time_unit, :microsecond) additional_attributes = Keyword.get(config, :additional_attributes, %{}) db_type = case type do :ecto_sql_query -> :sql _ -> type end # TODO: need connection information to complete the required attributes # net.peer.name or net.peer.ip and net.peer.port base_attributes = %{ "db.type": db_type, "db.statement": query, source: source, "db.instance": database, "db.name": database, "db.url": url, "total_time_#{time_unit}s": System.convert_time_unit(total_time, :native, time_unit) } attributes = measurements |> Enum.reduce(%{}, fn {k, v}, acc when not is_nil(v) and k in [:decode_time, :query_time, :queue_time, :idle_time] -> Map.put(acc, String.to_atom("#{k}_#{time_unit}s"), System.convert_time_unit(v, :native, time_unit)) _, acc -> acc end) |> Map.merge(base_attributes) |> Map.merge(additional_attributes) parent_context = case OpentelemetryProcessPropagator.fetch_ctx(self()) do :undefined -> OpentelemetryProcessPropagator.fetch_parent_ctx(1, :"$callers") ctx -> ctx end parent_token = if parent_context != :undefined do OpenTelemetry.Ctx.attach(parent_context) else :undefined end s = OpenTelemetry.Tracer.start_span(span_name, %{ start_time: start_time, attributes: attributes, kind: :client }) case query_result do {:error, error} -> OpenTelemetry.Span.set_status(s, OpenTelemetry.status(:error, format_error(error))) {:ok, _} -> :ok end OpenTelemetry.Span.end_span(s) if parent_token != :undefined do OpenTelemetry.Ctx.detach(parent_token) end end defp format_error(%{__exception__: true} = exception) do Exception.message(exception) end defp format_error(_), do: "" end