[Tesla middleware] `non_error_statuses` option (#154)

* [Tesla middleware] `non_error_statuses` option

* :mark_status_ok option instead of :non_error_statuses

---------

Co-authored-by: Tristan Sloughter <t@crashfast.com>

instrumentation/opentelemetry_tesla/lib/middleware/opentelemetry_tesla_middleware.ex

@@ -12,7 +12,8 @@ defmodule Tesla.Middleware.OpenTelemetry do
 
     - `:span_name` - override span name. Can be a `String` for a static span name,
     or a function that takes the `Tesla.Env` and returns a `String`
-
+    - `:mark_status_ok` - configures spans with a list of expected HTTP error codes to be marked as `ok`,
+    not as an error-containing spans
   """
 
   alias OpenTelemetry.SemanticConventions.Trace
@@ -27,6 +28,7 @@ defmodule Tesla.Middleware.OpenTelemetry do
 
     OpenTelemetry.Tracer.with_span span_name, %{kind: :client} do
       env
+      |> maybe_put_additional_ok_statuses(opts[:mark_status_ok])
       |> Tesla.put_headers(:otel_propagator_text_map.inject([]))
       |> Tesla.run(next)
       |> set_span_attributes()
@@ -49,6 +51,15 @@ defmodule Tesla.Middleware.OpenTelemetry do
     end
   end
 
+  defp maybe_put_additional_ok_statuses(env, [_ | _] = additional_ok_statuses) do
+    case env.opts[:additional_ok_statuses] do
+      nil -> Tesla.put_opt(env, :additional_ok_statuses, additional_ok_statuses)
+      _ -> env
+    end
+  end
+
+  defp maybe_put_additional_ok_statuses(env, _additional_ok_statuses), do: env
+
   defp set_span_attributes({_, %Tesla.Env{} = env} = result) do
     OpenTelemetry.Tracer.set_attributes(build_attrs(env))
 
@@ -59,8 +70,13 @@ defmodule Tesla.Middleware.OpenTelemetry do
     result
   end
 
-  defp handle_result({:ok, %Tesla.Env{status: status} = env}) when status >= 400 do
+  defp handle_result({:ok, %Tesla.Env{status: status, opts: opts} = env}) when status >= 400 do
-    OpenTelemetry.Tracer.set_status(OpenTelemetry.status(:error, ""))
+    span_status =
+      if status in Keyword.get(opts, :additional_ok_statuses, []), do: :ok, else: :error
+
+    span_status
+    |> OpenTelemetry.status("")
+    |> OpenTelemetry.Tracer.set_status()
 
     {:ok, env}
   end

instrumentation/opentelemetry_tesla/test/middleware/opentelemetry_tesla_middleware_test.exs

@@ -289,6 +289,64 @@ defmodule Tesla.Middleware.OpenTelemetryTest do
     assert_receive {:span, span(status: {:status, :error, ""})}
   end
 
+  test "Marks Span status as :error if error status is within `mark_status_ok` opt list",
+       %{bypass: bypass} do
+    defmodule TestClient do
+      def get(client) do
+        Tesla.get(client, "/users/")
+      end
+
+      def client(url) do
+        middleware = [
+          {Tesla.Middleware.BaseUrl, url},
+          {Tesla.Middleware.OpenTelemetry, mark_status_ok: [404]}
+        ]
+
+        Tesla.client(middleware)
+      end
+    end
+
+    Bypass.expect_once(bypass, "GET", "/users", fn conn ->
+      Plug.Conn.resp(conn, 404, "")
+    end)
+
+    bypass.port
+    |> endpoint_url()
+    |> TestClient.client()
+    |> TestClient.get()
+
+    assert_receive {:span, span(status: {:status, :ok, ""})}
+  end
+
+  test "Marks Span status as :ok unless error status is within `mark_status_ok` opt list",
+       %{bypass: bypass} do
+    defmodule TestClient do
+      def get(client) do
+        Tesla.get(client, "/users/")
+      end
+
+      def client(url) do
+        middleware = [
+          {Tesla.Middleware.BaseUrl, url},
+          {Tesla.Middleware.OpenTelemetry, mark_status_ok: []}
+        ]
+
+        Tesla.client(middleware)
+      end
+    end
+
+    Bypass.expect_once(bypass, "GET", "/users", fn conn ->
+      Plug.Conn.resp(conn, 404, "")
+    end)
+
+    bypass.port
+    |> endpoint_url()
+    |> TestClient.client()
+    |> TestClient.get()
+
+    assert_receive {:span, span(status: {:status, :error, ""})}
+  end
+
   test "Appends query string parameters to http.url attribute", %{bypass: bypass} do
     defmodule TestClient do
       def get(client, id) do