feat: add new metadata to Datadog traces (attempt 2)

apps/omg_watcher_rpc/lib/application.ex

@@ -29,7 +29,8 @@ defmodule OMG.WatcherRPC.Application do
     _ =
       SpandexPhoenix.Telemetry.install(
         endpoint_telemetry_prefix: [:watcher_rpc, :endpoint],
-        tracer: OMG.WatcherRPC.Tracer
+        tracer: OMG.WatcherRPC.Tracer,
+        customize_metadata: &OMG.WatcherRPC.Tracer.add_trace_metadata/1
       )
 
     children = [

apps/omg_watcher_rpc/lib/configuration.ex

@@ -0,0 +1,30 @@
+# Copyright 2019-2020 OmiseGO Pte Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+defmodule OMG.WatcherRPC.Configuration do
+  @moduledoc """
+  Provides access to applications configuration
+  """
+  @app :omg_watcher_rpc
+
+  @spec version() :: String.t()
+  def version() do
+    OMG.Utils.HttpRPC.Response.version(@app)
+  end
+
+  @spec service_name() :: atom()
+  def service_name() do
+    Application.get_env(@app, :api_mode)
+  end
+end

apps/omg_watcher_rpc/lib/tracer.ex

@@ -18,4 +18,26 @@ defmodule OMG.WatcherRPC.Tracer do
   """
 
   use Spandex.Tracer, otp_app: :omg_watcher_rpc
+  alias OMG.WatcherRPC.Configuration
+
+  def add_trace_metadata(%{assigns: %{error_type: error_type, error_msg: error_msg}} = conn) do
+    service_name = Configuration.service_name()
+    version = Configuration.version()
+
+    conn
+    |> SpandexPhoenix.default_metadata()
+    |> Keyword.put(:service, service_name)
+    |> Keyword.put(:error, [{:error, true}])
+    |> Keyword.put(:tags, [{:version, version}, {:"error.type", error_type}, {:"error.msg", error_msg}])
+  end
+
+  def add_trace_metadata(conn) do
+    service_name = Configuration.service_name()
+    version = Configuration.version()
+
+    conn
+    |> SpandexPhoenix.default_metadata()
+    |> Keyword.put(:service, service_name)
+    |> Keyword.put(:tags, [{:version, version}])
+  end
 end

apps/omg_watcher_rpc/lib/web/response.ex

@@ -20,26 +20,21 @@ defmodule OMG.WatcherRPC.Web.Response do
   For the generic response, see `OMG.Utils.HttpRPC.Response`.
   """
 
-  @app :omg_watcher_rpc
+  alias OMG.WatcherRPC.Configuration
 
   @doc """
   Adds "version" and "service_name" to the response map.
   """
   @spec add_app_infos(map()) :: %{version: String.t(), service_name: String.t()}
   def add_app_infos(response) do
     response
-    |> Map.put(:version, version())
-    |> Map.put(:service_name, service_name())
-  end
-
-  defp version() do
-    OMG.Utils.HttpRPC.Response.version(@app)
-  end
-
-  defp service_name() do
-    case Application.get_env(@app, :api_mode) do
-      :watcher -> "watcher"
-      :watcher_info -> "watcher_info"
-    end
+    |> Map.put(:version, Configuration.version())
+    |> Map.put(
+      :service_name,
+      case Configuration.service_name() do
+        :watcher -> "watcher"
+        :watcher_info -> "watcher_info"
+      end
+    )
   end
 end

apps/omg_watcher_rpc/test/omg_watcher_rpc/tracer_test.exs

@@ -0,0 +1,107 @@
+# Copyright 2019-2020 OmiseGO Pte Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+defmodule OMG.WatcherRPC.TracerTest do
+  @app :omg_watcher_rpc
+
+  use ExUnit.Case
+  import Plug.Conn
+  alias OMG.WatcherRPC.Configuration
+  alias OMG.WatcherRPC.Tracer
+
+  setup do
+    original_mode = Application.get_env(:omg_watcher_rpc, :api_mode)
+    _ = on_exit(fn -> Application.put_env(:omg_watcher_rpc, :api_mode, original_mode) end)
+
+    :ok
+  end
+
+  test "api responses without errors get traced with metadata" do
+    :ok = Application.put_env(@app, :api_mode, :watcher)
+    version = Configuration.version()
+
+    resp_body = """
+    {
+      "data": [],
+      "service_name": "watcher",
+      "success": true,
+      "version": "#{version}"
+    }
+    """
+
+    conn =
+      :get
+      |> Phoenix.ConnTest.build_conn("/alerts.get")
+      |> Plug.Conn.resp(200, resp_body)
+
+    trace_metadata = Tracer.add_trace_metadata(conn)
+
+    expected =
+      Keyword.new([
+        {:tags, [version: version]},
+        {:service, :watcher},
+        {:http, [method: "GET", query_string: "", status_code: 200, url: "/alerts.get", user_agent: nil]},
+        {:resource, "GET /alerts.get"},
+        {:type, :web}
+      ])
+
+    assert trace_metadata == expected
+  end
+
+  test "if api responses with errors get traced with metadata" do
+    :ok = Application.put_env(@app, :api_mode, :watcher_info)
+    version = Configuration.version()
+
+    resp_body = """
+    {
+      "data": {
+      "code": "operation:not_found",
+      "description": "Operation cannot be found. Check request URL.",
+      "object": "error"
+      },
+      "service_name": "watcher_info",
+      "success": false,
+      "version": "#{version}"
+    }
+    """
+
+    conn =
+      :post
+      |> Phoenix.ConnTest.build_conn("/")
+      |> Plug.Conn.resp(200, resp_body)
+      |> assign(:error_type, "operation:not_found")
+      |> assign(:error_msg, "Operation cannot be found. Check request URL.")
+
+    trace_metadata = Tracer.add_trace_metadata(conn)
+
+    expected =
+      Keyword.new([
+        {
+          :tags,
+          [
+            {:version, version},
+            {:"error.type", "operation:not_found"},
+            {:"error.msg", "Operation cannot be found. Check request URL."}
+          ]
+        },
+        {:error, [error: true]},
+        {:service, :watcher_info},
+        {:http, [method: "POST", query_string: "", status_code: 200, url: "/", user_agent: nil]},
+        {:resource, "POST /"},
+        {:type, :web}
+      ])
+
+    assert trace_metadata == expected
+  end
+end