Zen and the Art of Elixir Applications Monitoring

app_start.ex

# We do this at compile-time as we don't have Mix available in releases.
@version Mix.Project.config().version

def start(_type, _args) do
  #...

  with {:ok, _} = result <- Supervisor.start_link(children, options) do
    MyApp.Fluxter.write("start", version: @version)
    result
  end
end

ecto_telemetry.ex

def handle_event([:my_app, :repo, :query], measurements, metadata, %{}) do
  fields =
    []
    |> Fluxter.put_request_id()
    |> include_if_present(measurements, :queue_time)
    |> include_if_present(measurements, :query_time)
    |> include_if_present(measurements, :decode_time)

  MyApp.Fluxter.write("ecto_repo_exec", [repo: metadata.repo], fields)
end

defp include_if_present(fields, measurements, key) do
  case measurements do
    %{^key => value} ->
      microseconds = System.convert_time_unit(value, :native, :microsecond)
      [{key, microseconds} | fields]
    _ ->
      fields
  end
end

sample_event.ex

# Measurements
%{
  queue_time: 14,
  query_time: 57,
  decode_time: 4
}

# Metadata
%{
  repo: "foo"
}