Update x-goog-api-client metadata header to use a interceptor.

This change introduces a MetadataInterceptor to handle the addition of developer-token, login-customer-id, linked-customer-id, and x-goog-api-client modification, similar to the Python implementation.
The ServiceLookup and generated factories are updated to use this new interceptor.
Also added a test for the new interceptor.

Co-authored-by: dorasun <10905385+dorasun@users.noreply.github.com>

Author: google-labs-jules[bot]

codegen/templates/services.rb.erb

@@ -9,6 +9,7 @@ module Google
             def initialize(
               logging_interceptor:,
               error_interceptor:,
+              metadata_interceptor:,
               credentials:,
               metadata:,
               endpoint:,
@@ -17,6 +18,7 @@ module Google
               @interceptors = [
                 error_interceptor,
                 logging_interceptor,
+                metadata_interceptor
               ].compact
               @credentials = credentials
               @metadata = metadata

lib/google/ads/google_ads/interceptors/metadata_interceptor.rb

@@ -0,0 +1,73 @@
+# Encoding: utf-8
+#
+# Copyright 2022 Google LLC
+#
+# 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
+#
+#     https://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.
+#
+# Interceptor to add metadata headers to requests.
+
+require 'grpc/generic/interceptors'
+require 'google/protobuf'
+
+module Google
+  module Ads
+    module GoogleAds
+      module Interceptors
+        class MetadataInterceptor < GRPC::ClientInterceptor
+          def initialize(developer_token, login_customer_id, linked_customer_id, use_cloud_org_for_api_access)
+            super()
+            @developer_token = developer_token
+            @login_customer_id = login_customer_id
+            @linked_customer_id = linked_customer_id
+            @use_cloud_org_for_api_access = use_cloud_org_for_api_access
+          end
+
+          def request_response(request:, call:, method:, metadata: {})
+            update_metadata(metadata)
+            yield
+          end
+
+          def server_streamer(request:, call:, method:, metadata: {})
+            update_metadata(metadata)
+            yield
+          end
+
+          private
+
+          def update_metadata(metadata)
+            if !@use_cloud_org_for_api_access
+              metadata[:"developer-token"] = @developer_token
+            end
+
+            if @login_customer_id
+              metadata[:"login-customer-id"] = @login_customer_id.to_s
+            end
+
+            if @linked_customer_id
+              metadata[:"linked-customer-id"] = @linked_customer_id.to_s
+            end
+
+            # The python library iterates over metadata and modifies x-goog-api-client
+            # Here we can directly access it.
+            if metadata.key?(:"x-goog-api-client")
+              # Check if "pb" is already in the header
+              unless metadata[:"x-goog-api-client"].include?("pb")
+                metadata[:"x-goog-api-client"] += " pb/#{Gem.loaded_specs["google-protobuf"].version}"
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/google/ads/google_ads/service_lookup.rb

@@ -1,5 +1,6 @@
 require 'google/ads/google_ads/interceptors/logging_interceptor'
 require 'google/ads/google_ads/interceptors/error_interceptor'
+require 'google/ads/google_ads/interceptors/metadata_interceptor'
 
 module Google
   module Ads
@@ -26,27 +27,35 @@ def call
             logging_interceptor = GoogleAds::Interceptors::LoggingInterceptor.new(logger)
           end
           error_interceptor = GoogleAds::Interceptors::ErrorInterceptor.new
+          metadata_interceptor = GoogleAds::Interceptors::MetadataInterceptor.new(
+            config.developer_token,
+            config.login_customer_id,
+            config.linked_customer_id,
+            config.use_cloud_org_for_api_access
+          )
 
           version_alternates = {}
           Factories::VERSIONS.each do |v|
-            version_alternates[v] = factory_at_version(v, error_interceptor, logging_interceptor)
+            version_alternates[v] = factory_at_version(v, error_interceptor, logging_interceptor, metadata_interceptor)
           end
 
           highest_factory = factory_at_version(
             Factories::HIGHEST_VERSION,
             error_interceptor,
             logging_interceptor,
+            metadata_interceptor,
           )
 
           VersionAlternate.new(highest_factory, version_alternates)
         end
 
         private
 
-        def factory_at_version(version, error_interceptor, logging_interceptor)
+        def factory_at_version(version, error_interceptor, logging_interceptor, metadata_interceptor)
           factory = Factories.at_version(version).services.new(**{
             logging_interceptor: logging_interceptor,
             error_interceptor: error_interceptor,
+            metadata_interceptor: metadata_interceptor,
             deprecation: deprecator
           }.merge(gax_service_params))
 
@@ -62,27 +71,15 @@ def gax_service_params
         end
 
         def headers
-          headers = {}
-
-          # If config.use_cloud_org_for_api_access is not True, add the developer
-          # token to the request's metadata
-          if !config.use_cloud_org_for_api_access
-            headers[:"developer-token"] = config.developer_token
-          end
-
           if config.login_customer_id
             validate_customer_id(:login_customer_id)
-            # header values must be strings
-            headers[:"login-customer-id"] = config.login_customer_id.to_s
           end
 
           if config.linked_customer_id
             validate_customer_id(:linked_customer_id)
-            # header values must be strings
-            headers[:"linked-customer-id"] = config.linked_customer_id.to_s
           end
 
-          headers
+          {}
         end
 
         def validate_customer_id(field)

test/test_metadata_interceptor.rb

@@ -0,0 +1,86 @@
+#!/usr/bin/env ruby
+# Encoding: utf-8
+
+require 'minitest/autorun'
+require 'google/ads/google_ads/interceptors/metadata_interceptor'
+require 'google/protobuf'
+
+class TestMetadataInterceptor < Minitest::Test
+  attr_reader :mi
+
+  def setup
+    @mi = Google::Ads::GoogleAds::Interceptors::MetadataInterceptor.new(
+      "dev_token",
+      "login_id",
+      "linked_id",
+      false
+    )
+  end
+
+  def test_adds_developer_token_if_not_cloud_org
+    metadata = {}
+    mi.request_response(
+      request: nil,
+      call: nil,
+      method: nil,
+      metadata: metadata
+    ) do
+    end
+    assert_equal "dev_token", metadata[:"developer-token"]
+  end
+
+  def test_adds_login_and_linked_customer_id
+    metadata = {}
+    mi.request_response(
+      request: nil,
+      call: nil,
+      method: nil,
+      metadata: metadata
+    ) do
+    end
+    assert_equal "login_id", metadata[:"login-customer-id"]
+    assert_equal "linked_id", metadata[:"linked-customer-id"]
+  end
+
+  def test_appends_pb_version_to_x_goog_api_client
+    metadata = { :"x-goog-api-client" => "gl-ruby/1.2.3" }
+    mi.request_response(
+      request: nil,
+      call: nil,
+      method: nil,
+      metadata: metadata
+    ) do
+    end
+    assert_includes metadata[:"x-goog-api-client"], "pb/#{Gem.loaded_specs["google-protobuf"].version}"
+  end
+
+  def test_does_not_duplicate_pb_version
+    metadata = { :"x-goog-api-client" => "gl-ruby/1.2.3 pb/1.2.3" }
+    mi.request_response(
+      request: nil,
+      call: nil,
+      method: nil,
+      metadata: metadata
+    ) do
+    end
+    assert_equal "gl-ruby/1.2.3 pb/1.2.3", metadata[:"x-goog-api-client"]
+  end
+
+  def test_skips_developer_token_if_cloud_org
+    mi_cloud = Google::Ads::GoogleAds::Interceptors::MetadataInterceptor.new(
+      "dev_token",
+      "login_id",
+      "linked_id",
+      true
+    )
+    metadata = {}
+    mi_cloud.request_response(
+      request: nil,
+      call: nil,
+      method: nil,
+      metadata: metadata
+    ) do
+    end
+    assert_nil metadata[:"developer-token"]
+  end
+end