diff --git a/google-cloud-spanner/acceptance/spanner/client_test.rb b/google-cloud-spanner/acceptance/spanner/client_test.rb
new file mode 100644
index 000000000000..111388db6175
--- /dev/null
+++ b/google-cloud-spanner/acceptance/spanner/client_test.rb
@@ -0,0 +1,36 @@
+# Copyright 2020 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.
+
+require "spanner_helper"
+require "concurrent"
+
+describe "Spanner Client", :spanner do
+  let(:spanner) { $spanner }
+  let(:instance_id) { $spanner_instance_id }
+  let(:database_id) { $spanner_database_id }
+
+  it "create client connection without resource based routing" do
+    client = spanner.client instance_id, database_id
+    client.service.host.must_equal Google::Cloud::Spanner::V1::SpannerClient::SERVICE_ADDRESS
+  end
+
+  it "create client connection with resource based routing" do
+    client = spanner.client instance_id, database_id, enable_resource_based_routing: true
+    client.resource_based_routing_enabled?.must_equal true
+    instance = spanner.instance instance_id, fields: ["endpoint_uris"]
+    # Set to default if no endpoint uri present.
+    host = instance.endpoint_uris.first || Google::Cloud::Spanner::V1::SpannerClient::SERVICE_ADDRESS
+    client.service.host.must_equal host
+  end
+end
diff --git a/google-cloud-spanner/acceptance/spanner/instance_test.rb b/google-cloud-spanner/acceptance/spanner/instance_test.rb
index 4a12f9e8f715..838b657ca0db 100644
--- a/google-cloud-spanner/acceptance/spanner/instance_test.rb
+++ b/google-cloud-spanner/acceptance/spanner/instance_test.rb
@@ -15,6 +15,8 @@
 require "spanner_helper"
 
 describe "Spanner Instances", :spanner do
+  let(:instance_id) { $spanner_instance_id }
+
   it "lists and gets instances" do
     all_instances = spanner.instances.all.to_a
     all_instances.wont_be :empty?
@@ -26,6 +28,28 @@
     first_instance.must_be_kind_of Google::Cloud::Spanner::Instance
   end
 
+  describe "get instance" do
+    it "get all instance fields" do
+      instance = spanner.instance instance_id
+
+      instance.instance_id.must_equal instance_id
+      instance.path.wont_be_empty
+      instance.display_name.wont_be_empty
+      instance.nodes.must_be :>, 0
+      instance.state.must_equal :READY
+    end
+
+    it "get specified instance fields" do
+      instance = spanner.instance instance_id, fields: ["name"]
+
+      instance.instance_id.must_equal instance_id
+      instance.path.wont_be_empty
+      instance.display_name.must_be_empty
+      instance.nodes.must_equal 0
+      instance.state.must_equal :STATE_UNSPECIFIED
+    end
+  end
+
   describe "IAM Policies and Permissions" do
     let(:service_account) { spanner.service.credentials.client.issuer }
 
diff --git a/google-cloud-spanner/acceptance/spanner_helper.rb b/google-cloud-spanner/acceptance/spanner_helper.rb
index 409fa19e926b..72b6c44deac1 100644
--- a/google-cloud-spanner/acceptance/spanner_helper.rb
+++ b/google-cloud-spanner/acceptance/spanner_helper.rb
@@ -254,9 +254,9 @@ def default_item_rows
 fixture = Object.new
 fixture.extend Acceptance::SpannerTest::Fixtures
 
-instance = $spanner.instance "google-cloud-ruby-tests"
+instance = $spanner.instance $spanner_instance_id
 instance ||= begin
-  inst_job = $spanner.create_instance "google-cloud-ruby-tests", name: "google-cloud-ruby-tests", config: "regional-us-central1", nodes: 1
+  inst_job = $spanner.create_instance $spanner_instance_id, name: $spanner_instance_id, config: "regional-us-central1", nodes: 1
   inst_job.wait_until_done!
   fail GRPC::BadStatus.new(inst_job.error.code, inst_job.error.message) if inst_job.error?
   inst_job.instance
diff --git a/google-cloud-spanner/lib/google/cloud/spanner/batch_client.rb b/google-cloud-spanner/lib/google/cloud/spanner/batch_client.rb
index c36d538f07e9..c5682f44d4f5 100644
--- a/google-cloud-spanner/lib/google/cloud/spanner/batch_client.rb
+++ b/google-cloud-spanner/lib/google/cloud/spanner/batch_client.rb
@@ -17,6 +17,7 @@
 require "google/cloud/spanner/project"
 require "google/cloud/spanner/session"
 require "google/cloud/spanner/batch_snapshot"
+require "google/cloud/spanner/resource_based_routing"
 
 module Google
   module Cloud
@@ -63,13 +64,32 @@ module Spanner
       #     new_partition
       #
       class BatchClient
+        # @!parse extend ResourceBasedRouting
+        include ResourceBasedRouting
+
+        ## @private Service wrapper for batch data client api.
+        # @return [ClientServiceProxy]
+        attr_reader :service
+
         ##
         # @private Creates a new Spanner BatchClient instance.
-        def initialize project, instance_id, database_id, session_labels: nil
+        def initialize \
+            project,
+            instance_id,
+            database_id,
+            session_labels: nil,
+            enable_resource_based_routing: false
           @project = project
           @instance_id = instance_id
           @database_id = database_id
           @session_labels = session_labels
+          @enable_resource_based_routing = enable_resource_based_routing
+
+          if resource_based_routing_enabled?
+            @service = resource_based_routing_service
+          end
+
+          @service ||= @project.service
         end
 
         # The unique identifier for the project.
@@ -184,7 +204,7 @@ def batch_snapshot strong: nil, timestamp: nil, read_timestamp: nil,
 
           ensure_service!
           snp_session = session
-          snp_grpc = @project.service.create_snapshot \
+          snp_grpc = @service.create_snapshot \
             snp_session.path, strong: strong,
                               timestamp: (timestamp || read_timestamp),
                               staleness: (staleness || exact_staleness)
@@ -231,7 +251,7 @@ def batch_snapshot strong: nil, timestamp: nil, read_timestamp: nil,
         def load_batch_snapshot serialized_snapshot
           ensure_service!
 
-          BatchSnapshot.load serialized_snapshot, service: @project.service
+          BatchSnapshot.load serialized_snapshot, service: @service
         end
 
         ##
@@ -404,12 +424,12 @@ def ensure_service!
         # New session for each use.
         def session
           ensure_service!
-          grpc = @project.service.create_session \
+          grpc = @service.create_session \
             Admin::Database::V1::DatabaseAdminClient.database_path(
               project_id, instance_id, database_id
             ),
             labels: @session_labels
-          Session.from_grpc grpc, @project.service
+          Session.from_grpc grpc, @service
         end
 
         ##
diff --git a/google-cloud-spanner/lib/google/cloud/spanner/client.rb b/google-cloud-spanner/lib/google/cloud/spanner/client.rb
index 5cc3550bd73f..aa6e383de8f5 100644
--- a/google-cloud-spanner/lib/google/cloud/spanner/client.rb
+++ b/google-cloud-spanner/lib/google/cloud/spanner/client.rb
@@ -23,6 +23,7 @@
 require "google/cloud/spanner/range"
 require "google/cloud/spanner/column_value"
 require "google/cloud/spanner/convert"
+require "google/cloud/spanner/resource_based_routing"
 
 module Google
   module Cloud
@@ -49,22 +50,57 @@ module Spanner
       #     end
       #   end
       #
+      # @example Enable resource based routing.
+      #
+      #   require "google/cloud"
+      #
+      #   spanner = Google::Cloud::Spanner.new
+      #
+      #   db = spanner.client(
+      #     "my-instance",
+      #     "my-database",
+      #     enable_resource_based_routing: true
+      #   )
+      #
+      #   db.transaction do |tx|
+      #     results = tx.execute_query "SELECT * FROM users"
+      #
+      #     results.rows.each do |row|
+      #       puts "User #{row[:id]} is #{row[:name]}"
+      #     end
+      #   end
+      #
       class Client
+        # @!parse extend ResourceBasedRouting
+        include ResourceBasedRouting
+
+        ##
+        # @private The Service object.
+        # @return [Spanner::Service]
+        attr_reader :service
+
         ##
         # @private Creates a new Spanner Client instance.
         def initialize project, instance_id, database_id, session_labels: nil,
-                       pool_opts: {}
+                       pool_opts: {}, enable_resource_based_routing: false
           @project = project
           @instance_id = instance_id
           @database_id = database_id
           @session_labels = session_labels
+          @enable_resource_based_routing = enable_resource_based_routing
+
+          if resource_based_routing_enabled?
+            @service = resource_based_routing_service
+          end
+
+          @service ||= @project.service
           @pool = Pool.new self, pool_opts
         end
 
         # The unique identifier for the project.
         # @return [String]
         def project_id
-          @project.service.project
+          @service.project
         end
 
         # The unique identifier for the instance.
@@ -920,8 +956,7 @@ def commit &block
           end
         end
 
-        # rubocop:disable Metrics/AbcSize
-        # rubocop:disable Metrics/MethodLength
+        # rubocop:disable Metrics/AbcSize,Metrics/MethodLength
 
         ##
         # Creates a transaction for reads and writes that execute atomically at
@@ -994,7 +1029,7 @@ def transaction deadline: 120
             begin
               Thread.current[:transaction_id] = tx.transaction_id
               yield tx
-              commit_resp = @project.service.commit \
+              commit_resp = @service.commit \
                 tx.session.path, tx.mutations, transaction_id: tx.transaction_id
               return Convert.timestamp_to_time commit_resp.commit_timestamp
             rescue GRPC::Aborted, Google::Cloud::AbortedError => err
@@ -1022,9 +1057,7 @@ def transaction deadline: 120
             end
           end
         end
-
-        # rubocop:enable Metrics/AbcSize
-        # rubocop:enable Metrics/MethodLength
+        # rubocop:enable Metrics/AbcSize,Metrics/MethodLength
 
         ##
         # Creates a snapshot read-only transaction for reads that execute
@@ -1093,7 +1126,7 @@ def snapshot strong: nil, timestamp: nil, read_timestamp: nil,
 
           @pool.with_session do |session|
             begin
-              snp_grpc = @project.service.create_snapshot \
+              snp_grpc = @service.create_snapshot \
                 session.path, strong: strong,
                               timestamp: (timestamp || read_timestamp),
                               staleness: (staleness || exact_staleness)
@@ -1286,12 +1319,12 @@ def reset
         # Creates a new session object every time.
         def create_new_session
           ensure_service!
-          grpc = @project.service.create_session \
+          grpc = @service.create_session \
             Admin::Database::V1::DatabaseAdminClient.database_path(
               project_id, instance_id, database_id
             ),
             labels: @session_labels
-          Session.from_grpc grpc, @project.service
+          Session.from_grpc grpc, @service
         end
 
         ##
@@ -1314,13 +1347,13 @@ def batch_create_new_sessions total
         #
         def batch_create_sessions session_count
           ensure_service!
-          resp = @project.service.batch_create_sessions \
+          resp = @service.batch_create_sessions \
             Admin::Database::V1::DatabaseAdminClient.database_path(
               project_id, instance_id, database_id
             ),
             session_count,
             labels: @session_labels
-          resp.session.map { |grpc| Session.from_grpc grpc, @project.service }
+          resp.session.map { |grpc| Session.from_grpc grpc, @service }
         end
 
         # @private
@@ -1340,7 +1373,7 @@ def inspect
         # @private Raise an error unless an active connection to the service is
         # available.
         def ensure_service!
-          raise "Must have active connection to service" unless @project.service
+          raise "Must have active connection to service" unless @service
         end
 
         ##
@@ -1385,7 +1418,7 @@ def single_use_transaction opts
         end
 
         def pdml_transaction session
-          pdml_tx_grpc = @project.service.create_pdml session.path
+          pdml_tx_grpc = @service.create_pdml session.path
           Google::Spanner::V1::TransactionSelector.new id: pdml_tx_grpc.id
         end
 
diff --git a/google-cloud-spanner/lib/google/cloud/spanner/instance.rb b/google-cloud-spanner/lib/google/cloud/spanner/instance.rb
index 551abc01537a..92d1be7bc060 100644
--- a/google-cloud-spanner/lib/google/cloud/spanner/instance.rb
+++ b/google-cloud-spanner/lib/google/cloud/spanner/instance.rb
@@ -188,6 +188,20 @@ def labels= labels
           )
         end
 
+        ##
+        # The endpoint URIs based on the instance config.
+        # For example, instances located in a specific cloud region
+        # (or multi region) such as nam3, would have a nam3 specific
+        # endpoint URI. These endpoints are intended to optimize the network
+        # routing between the client and the instance's serving resources.
+        # If multiple endpoints are present, client may establish connections
+        # using any of the given URLs.
+        #
+        # @return [Array<String>] The list of URIs.
+        def endpoint_uris
+          @grpc.endpoint_uris
+        end
+
         def save
           job_grpc = service.update_instance @grpc
           Instance::Job.from_grpc job_grpc, service
diff --git a/google-cloud-spanner/lib/google/cloud/spanner/project.rb b/google-cloud-spanner/lib/google/cloud/spanner/project.rb
index 229702bac7f4..e1ff181792ec 100644
--- a/google-cloud-spanner/lib/google/cloud/spanner/project.rb
+++ b/google-cloud-spanner/lib/google/cloud/spanner/project.rb
@@ -135,7 +135,9 @@ def instances token: nil, max: nil
         # Retrieves a Cloud Spanner instance by unique identifier.
         #
         # @param [String] instance_id The unique identifier for the instance.
-        #
+        # @param [Array<String>] fields Specifies the subset of fields that
+        #   should be returned. If fields are not provided then all fields will
+        #   be returned. Optional.
         # @return [Google::Cloud::Spanner::Instance, nil] The instance, or `nil`
         #   if the instance does not exist.
         #
@@ -151,9 +153,16 @@ def instances token: nil, max: nil
         #   spanner = Google::Cloud::Spanner.new
         #   instance = spanner.instance "non-existing" # nil
         #
-        def instance instance_id
+        # @example Get instance details with specified fields.
+        #   require "google/cloud/spanner"
+        #
+        #   spanner = Google::Cloud::Spanner.new
+        #   instance = spanner.instance "my-instance", fields: ["name"]
+        #
+        def instance instance_id, fields: nil
           ensure_service!
-          grpc = service.get_instance instance_id
+
+          grpc = service.get_instance instance_id, fields: fields
           Instance.from_grpc grpc, service
         rescue Google::Cloud::NotFoundError
           nil
@@ -452,7 +461,11 @@ def create_database instance_id, database_id, statements: []
         #   * Label values must be between 0 and 63 characters long and must
         #     conform to the regular expression `([a-z]([-a-z0-9]*[a-z0-9])?)?`.
         #   * No more than 64 labels can be associated with a given resource.
-        #
+        # @param [Boolean] enable_resource_based_routing Enable/Disable
+        #   resource-based routing for data operation, by default it is
+        #   disabled. Resource based routing can be enabled using the
+        #   environment `GOOGLE_CLOUD_SPANNER_ENABLE_RESOURCE_BASED_ROUTING` to
+        #   `TRUE` or `true`.
         # @return [Client] The newly created client.
         #
         # @example
@@ -470,12 +483,37 @@ def create_database instance_id, database_id, statements: []
         #     end
         #   end
         #
-        def client instance_id, database_id, pool: {}, labels: nil
+        # @example Enable resource based routing.
+        #   require "google/cloud/spanner"
+        #
+        #   spanner = Google::Cloud::Spanner.new
+        #
+        #   db = spanner.client \
+        #     "my-instance", "my-database", enable_resource_based_routing: true
+        #
+        #   db.transaction do |tx|
+        #     results = tx.execute_query "SELECT * FROM users"
+        #
+        #     results.rows.each do |row|
+        #       puts "User #{row[:id]} is #{row[:name]}"
+        #     end
+        #   end
+        #
+        def client \
+            instance_id,
+            database_id,
+            pool: {},
+            labels: nil,
+            enable_resource_based_routing: false
           # Convert from possible Google::Protobuf::Map
           labels = Hash[labels.map { |k, v| [String(k), String(v)] }] if labels
-          Client.new self, instance_id, database_id,
-                     session_labels: labels,
-                     pool_opts: valid_session_pool_options(pool)
+          Client.new \
+            self,
+            instance_id,
+            database_id,
+            session_labels: labels,
+            pool_opts: valid_session_pool_options(pool),
+            enable_resource_based_routing: enable_resource_based_routing
         end
 
         ##
@@ -501,6 +539,11 @@ def client instance_id, database_id, pool: {}, labels: nil
         #   * Label values must be between 0 and 63 characters long and must
         #     conform to the regular expression `([a-z]([-a-z0-9]*[a-z0-9])?)?`.
         #   * No more than 64 labels can be associated with a given resource.
+        # @param [Boolean] enable_resource_based_routing Enable/Disable
+        #   resource-based routing for data operation, by default it
+        #   is disabled. Resource based routing can be enabled using the
+        #   environment `GOOGLE_CLOUD_SPANNER_ENABLE_RESOURCE_BASED_ROUTING` to
+        #   `TRUE` or `true`.
         #
         # @return [Client] The newly created client.
         #
@@ -529,10 +572,45 @@ def client instance_id, database_id, pool: {}, labels: nil
         #   results = new_batch_snapshot.execute_partition \
         #     new_partition
         #
-        def batch_client instance_id, database_id, labels: nil
+        # @example Enable resource based routing.
+        #   require "google/cloud/spanner"
+        #
+        #   spanner = Google::Cloud::Spanner.new
+        #
+        #   batch_client = spanner.batch_client \
+        #     "my-instance", "my-database", enable_resource_based_routing: true
+        #
+        #   batch_snapshot = batch_client.batch_snapshot
+        #   serialized_snapshot = batch_snapshot.dump
+        #
+        #   partitions = batch_snapshot.partition_read "users", [:id, :name]
+        #
+        #   partition = partitions.first
+        #   serialized_partition = partition.dump
+        #
+        #   # In a separate process
+        #   new_batch_snapshot = batch_client.load_batch_snapshot \
+        #     serialized_snapshot
+        #
+        #   new_partition = batch_client.load_partition \
+        #     serialized_partition
+        #
+        #   results = new_batch_snapshot.execute_partition \
+        #     new_partition
+        #
+        def batch_client \
+            instance_id,
+            database_id,
+            labels: nil,
+            enable_resource_based_routing: false
           # Convert from possible Google::Protobuf::Map
           labels = Hash[labels.map { |k, v| [String(k), String(v)] }] if labels
-          BatchClient.new self, instance_id, database_id, session_labels: labels
+          BatchClient.new \
+            self,
+            instance_id,
+            database_id,
+            session_labels: labels,
+            enable_resource_based_routing: enable_resource_based_routing
         end
 
         protected
diff --git a/google-cloud-spanner/lib/google/cloud/spanner/resource_based_routing.rb b/google-cloud-spanner/lib/google/cloud/spanner/resource_based_routing.rb
new file mode 100644
index 000000000000..2f09f8a5d4f3
--- /dev/null
+++ b/google-cloud-spanner/lib/google/cloud/spanner/resource_based_routing.rb
@@ -0,0 +1,63 @@
+# Copyright 2020 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.
+
+
+module Google
+  module Cloud
+    module Spanner
+      ##
+      # @private Helper module for resource based routing client.
+      module ResourceBasedRouting
+        # Check resource based routing is enabled or not.
+        #
+        # @return [Boolean]
+        def resource_based_routing_enabled?
+          return true if @enable_resource_based_routing
+
+          ["TRUE", "true"].include? \
+            ENV["GOOGLE_CLOUD_SPANNER_ENABLE_RESOURCE_BASED_ROUTING"]
+        end
+
+        protected
+
+        # Returns a Service that uses the first endpoint uri for the instance.
+        #
+        # @return [Spanner::Service, nil] Returns service instance if instance
+        #   endpoint uris present.
+        def resource_based_routing_service
+          instance = @project.instance @instance_id, fields: ["endpoint_uris"]
+          return if instance.nil? || instance.endpoint_uris.empty?
+
+          Spanner::Service.new \
+            @project.project_id,
+            @project.service.credentials,
+            host: instance.endpoint_uris.first,
+            timeout: @project.service.timeout,
+            client_config: @project.service.client_config
+        rescue Google::Cloud::PermissionDeniedError
+          warn <<~WARN
+            The client library attempted to connect to an endpoint
+            closer to your Cloud Spanner data but was unable to do so.
+            The client library will fallback and route requests to the
+            endpoint given in the client options, which may result in
+            increased latency. We recommend including the scope
+            https://www.googleapis.com/auth/spanner.admin so that
+            the client library can get an instance-specific endpoint
+            and efficiently route requests.
+          WARN
+        end
+      end
+    end
+  end
+end
diff --git a/google-cloud-spanner/lib/google/cloud/spanner/service.rb b/google-cloud-spanner/lib/google/cloud/spanner/service.rb
index 1f758e370b3d..acb69f76aee5 100644
--- a/google-cloud-spanner/lib/google/cloud/spanner/service.rb
+++ b/google-cloud-spanner/lib/google/cloud/spanner/service.rb
@@ -120,9 +120,11 @@ def list_instances token: nil, max: nil
           end
         end
 
-        def get_instance name
+        def get_instance name, fields: nil
+          field_mask = Google::Protobuf::FieldMask.new(paths: fields || [])
+
           execute do
-            instances.get_instance instance_path(name)
+            instances.get_instance instance_path(name), field_mask: field_mask
           end
         end
 
@@ -284,10 +286,11 @@ def batch_create_sessions database_name, session_count, labels: nil
           session = Google::Spanner::V1::Session.new labels: labels if labels
           execute do
             # The response may have fewer sessions than requested in the RPC.
-            service.batch_create_sessions database_name,
-                                          session_count,
-                                          session_template: session,
-                                          options: opts
+            service.batch_create_sessions \
+              database_name,
+              session_count,
+              session_template: session,
+              options: opts
           end
         end
 
@@ -318,11 +321,12 @@ def execute_batch_dml session_name, transaction, statements, seqno
           opts = default_options_from_session session_name
           statements = statements.map(&:to_grpc)
           results = execute do
-            service.execute_batch_dml session_name,
-                                      transaction,
-                                      statements,
-                                      seqno,
-                                      options: opts
+            service.execute_batch_dml \
+              session_name,
+              transaction,
+              statements,
+              seqno,
+              options: opts
           end
           if results.status.code.zero?
             results.result_sets.map { |rs| rs.stats.row_count_exact }
@@ -392,7 +396,8 @@ def commit session_name, mutations = [], transaction_id: nil
           execute do
             service.commit \
               session_name, mutations,
-              transaction_id: transaction_id, single_use_transaction: tx_opts,
+              transaction_id: transaction_id,
+              single_use_transaction: tx_opts,
               options: opts
           end
         end
@@ -439,7 +444,8 @@ def create_pdml session_name
           )
           opts = default_options_from_session session_name
           execute do
-            service.begin_transaction session_name, tx_opts, options: opts
+            service.begin_transaction \
+              session_name, tx_opts, options: opts
           end
         end
 
diff --git a/google-cloud-spanner/support/doctest_helper.rb b/google-cloud-spanner/support/doctest_helper.rb
index 5e02001bb434..bd62bb0c8729 100644
--- a/google-cloud-spanner/support/doctest_helper.rb
+++ b/google-cloud-spanner/support/doctest_helper.rb
@@ -108,14 +108,14 @@ def mock_spanner
       mock_client = Minitest::Mock.new
       mock_instances.expect :create_instance, create_instance_resp(client: mock_client), ["projects/my-project", "my-new-instance", Google::Spanner::Admin::Instance::V1::Instance]
       mock_client.expect :get_operation, OpenStruct.new(done: true), ["1234567890", {:options=>nil}]
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-new-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-new-instance", Hash]
     end
   end
 
   doctest.before "Google::Cloud::Spanner::Instance#create_database" do
     mock_spanner do |mock, mock_instances, mock_databases|
       mock_client = Minitest::Mock.new
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_client.expect :get_operation, OpenStruct.new(done: true), ["1234567890", {:options=>nil}]
       mock_databases.expect :create_database, create_database_resp(client: mock_client), ["projects/my-project/instances/my-instance", "CREATE DATABASE `my-new-database`", {:extra_statements=>[]}]
     end
@@ -123,21 +123,21 @@ def mock_spanner
 
   doctest.before "Google::Cloud::Spanner::Instance#database" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_databases.expect :get_database, database_resp, ["projects/my-project/instances/my-instance/databases/my-database"]
     end
   end
 
   doctest.before "Google::Cloud::Spanner::Instance#database@Will return `nil` if instance does not exist." do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_databases.expect :get_database, nil, ["projects/my-project/instances/my-instance/databases/my-database"]
     end
   end
 
   doctest.before "Google::Cloud::Spanner::Instance#databases" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_databases.expect :list_databases, databases_resp(token: "token"), ["projects/my-project/instances/my-instance", Hash]
       mock_databases.expect :list_databases, databases_resp, ["projects/my-project/instances/my-instance", Hash]
     end
@@ -145,7 +145,7 @@ def mock_spanner
 
   doctest.before "Google::Cloud::Spanner::Instance#policy" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_instances.expect :get_iam_policy, policy_resp, ["projects/my-project/instances/my-instance"]
       mock_instances.expect :set_iam_policy, policy_resp, ["projects/my-project/instances/my-instance", Google::Iam::V1::Policy]
     end
@@ -153,7 +153,7 @@ def mock_spanner
 
   doctest.before "Google::Cloud::Spanner::Instance#update_policy" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_instances.expect :get_iam_policy, policy_resp, ["projects/my-project/instances/my-instance"]
       mock_instances.expect :set_iam_policy, policy_resp, ["projects/my-project/instances/my-instance", Google::Iam::V1::Policy]
     end
@@ -161,14 +161,14 @@ def mock_spanner
 
   doctest.before "Google::Cloud::Spanner::Instance#test_permissions" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_instances.expect :test_iam_permissions, test_permissions_res, ["projects/my-project/instances/my-instance", ["spanner.instances.get", "spanner.instances.update"]]
     end
   end
 
   doctest.before "Google::Cloud::Spanner::Instance#delete" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_instances.expect :delete_instance, nil, ["projects/my-project/instances/my-instance"]
     end
   end
@@ -310,7 +310,7 @@ def mock_spanner
 
   doctest.before "Google::Cloud::Spanner::Policy" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_instances.expect :get_iam_policy, policy_resp, ["projects/my-project/instances/my-instance"]
       mock_instances.expect :set_iam_policy, policy_resp, ["projects/my-project/instances/my-instance", Google::Iam::V1::Policy]
     end
@@ -320,7 +320,7 @@ def mock_spanner
 
   doctest.before "Google::Cloud::Spanner::Project" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_databases.expect :get_database, database_resp, ["projects/my-project/instances/my-instance/databases/my-database"]
     end
   end
@@ -347,6 +347,18 @@ def mock_spanner
     end
   end
 
+  doctest.before "Google::Cloud::Spanner::Project#batch_client@Enable resource based routing." do
+    mock_spanner do |mock, mock_instances, mock_databases|
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
+      mock.expect :create_session, session_grpc, ["projects/my-project/instances/my-instance/databases/my-database", Hash]
+      mock.expect :begin_transaction, tx_resp, ["session-name", Google::Spanner::V1::TransactionOptions, Hash]
+      mock.expect :partition_read, OpenStruct.new(partitions: [Google::Spanner::V1::Partition.new(partition_token: "partition-token")]),
+                  ["session-name", "users", Google::Spanner::V1::KeySet, Hash]
+      mock.expect :streaming_read, results_enum, ["session-name", "users", ["id", "name"], Google::Spanner::V1::KeySet, Hash]
+      mock.expect :delete_session, session_grpc, ["session-name", Hash]
+    end
+  end
+
   doctest.before "Google::Cloud::Spanner::Project#client" do
     mock_spanner do |mock, mock_instances, mock_databases|
       mock.expect :batch_create_sessions, OpenStruct.new(session: Array.new(10) { session_grpc }), ["projects/my-project/instances/my-instance/databases/my-database", 10, Hash]
@@ -358,24 +370,36 @@ def mock_spanner
     end
   end
 
+  doctest.before "Google::Cloud::Spanner::Project#client@Enable resource based routing." do
+    mock_spanner do |mock, mock_instances, mock_databases|
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
+      mock.expect :batch_create_sessions, OpenStruct.new(session: Array.new(10) { session_grpc }), ["projects/my-project/instances/my-instance/databases/my-database", 10, Hash]
+      5.times do
+        mock.expect :begin_transaction, tx_resp, ["session-name", Google::Spanner::V1::TransactionOptions, Hash]
+      end
+      mock.expect :execute_streaming_sql, results_enum, ["session-name", "SELECT * FROM users", Hash]
+      mock.expect :commit, commit_resp, ["session-name", Array, Hash]
+    end
+  end
+
   doctest.before "Google::Cloud::Spanner::Project#create_instance" do
     mock_spanner do |mock, mock_instances, mock_databases|
       mock_client = Minitest::Mock.new
       mock_client.expect :get_operation, OpenStruct.new(done: true), ["1234567890", {:options=>nil}]
       mock_instances.expect :create_instance, create_instance_resp(client: mock_client), ["projects/my-project", "my-new-instance", Google::Spanner::Admin::Instance::V1::Instance]
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-new-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-new-instance", Hash]
     end
   end
 
   doctest.before "Google::Cloud::Spanner::Project#instance" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
     end
   end
 
   doctest.before "Google::Cloud::Spanner::Project#instance@Will return `nil` if instance does not exist." do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/non-existing"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/non-existing", Hash]
     end
   end
 
@@ -416,7 +440,7 @@ def mock_spanner
 
   doctest.before "Google::Cloud::Spanner::Project#databases" do
     mock_spanner do |mock, mock_instances, mock_databases|
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_databases.expect :list_databases, databases_resp(token: "token"), ["projects/my-project/instances/my-instance", Hash]
       mock_databases.expect :list_databases, databases_resp, ["projects/my-project/instances/my-instance", Hash]
     end
@@ -435,6 +459,18 @@ def mock_spanner
     end
   end
 
+  doctest.before "Google::Cloud::Spanner::Client@Enable resource based routing." do
+    mock_spanner do |mock, mock_instances, mock_databases|
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
+      mock.expect :batch_create_sessions, OpenStruct.new(session: Array.new(10) { session_grpc }), ["projects/my-project/instances/my-instance/databases/my-database", 10, Hash]
+      5.times do
+        mock.expect :begin_transaction, tx_resp, ["session-name", Google::Spanner::V1::TransactionOptions, Hash]
+      end
+      mock.expect :execute_streaming_sql, results_enum, ["session-name", "SELECT * FROM users", Hash]
+      mock.expect :commit, commit_resp, ["session-name", Array, Hash]
+    end
+  end
+
   doctest.before "Google::Cloud::Spanner::Client#execute" do
     mock_spanner do |mock, mock_instances, mock_databases|
       mock.expect :batch_create_sessions, OpenStruct.new(session: Array.new(10) { session_grpc }), ["projects/my-project/instances/my-instance/databases/my-database", 10, Hash]
@@ -550,7 +586,7 @@ def mock_spanner
   doctest.before "Google::Cloud::Spanner::Database" do
     mock_spanner do |mock, mock_instances, mock_databases|
       mock_client = Minitest::Mock.new
-      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance"]
+      mock_instances.expect :get_instance, OpenStruct.new(instance_hash), ["projects/my-project/instances/my-instance", Hash]
       mock_client.expect :get_operation, OpenStruct.new(done: true), ["1234567890", {:options=>nil}]
       mock_databases.expect :create_database, create_database_resp(client: mock_client), ["projects/my-project/instances/my-instance", "CREATE DATABASE `my-new-database`", {:extra_statements=>[]}]
       mock_databases.expect :get_database, database_resp, ["projects/my-project/instances/my-instance/databases/my-new-database"]
@@ -826,17 +862,6 @@ def project
   "my-project"
 end
 
-def instance_hash name: "my-instance", nodes: 1, state: "READY", labels: {}
-  {
-    name: "projects/#{project}/instances/#{name}",
-    config: "projects/#{project}/instanceConfigs/regional-us-central1",
-    display_name: name.split("-").map(&:capitalize).join(" "),
-    nodeCount: nodes,
-    state: state,
-    labels: labels
-  }
-end
-
 def job_grpc
   Google::Longrunning::Operation.new(
     name: "1234567890",
@@ -895,7 +920,8 @@ def instance_hash name: "my-instance", nodes: 1, state: "READY", labels: {}
     display_name: name.split("-").map(&:capitalize).join(" "),
     node_count: nodes,
     state: state,
-    labels: labels
+    labels: labels,
+    endpoint_uris: []
   }
 end
 
diff --git a/google-cloud-spanner/test/google/cloud/spanner/batch_client_test.rb b/google-cloud-spanner/test/google/cloud/spanner/batch_client_test.rb
index 37c636cbd971..30b25805839b 100644
--- a/google-cloud-spanner/test/google/cloud/spanner/batch_client_test.rb
+++ b/google-cloud-spanner/test/google/cloud/spanner/batch_client_test.rb
@@ -48,7 +48,7 @@
   it "retrieves the instance" do
     get_res = Google::Spanner::Admin::Instance::V1::Instance.new instance_hash(name: instance_id)
     mock = Minitest::Mock.new
-    mock.expect :get_instance, get_res, [instance_path(instance_id)]
+    mock.expect :get_instance, get_res, [instance_path(instance_id), Hash]
     spanner.service.mocked_instances = mock
 
     instance = spanner.instance instance_id
diff --git a/google-cloud-spanner/test/google/cloud/spanner/client/admin_test.rb b/google-cloud-spanner/test/google/cloud/spanner/client/admin_test.rb
index 0ca0691cf5cb..9222e71eda41 100644
--- a/google-cloud-spanner/test/google/cloud/spanner/client/admin_test.rb
+++ b/google-cloud-spanner/test/google/cloud/spanner/client/admin_test.rb
@@ -42,7 +42,7 @@
   it "retrieves the instance" do
     get_res = Google::Spanner::Admin::Instance::V1::Instance.new instance_hash(name: instance_id)
     mock = Minitest::Mock.new
-    mock.expect :get_instance, get_res, [instance_path(instance_id)]
+    mock.expect :get_instance, get_res, [instance_path(instance_id), Hash]
     spanner.service.mocked_instances = mock
 
     instance = spanner.instance instance_id
diff --git a/google-cloud-spanner/test/google/cloud/spanner/client/resource_based_routing_test.rb b/google-cloud-spanner/test/google/cloud/spanner/client/resource_based_routing_test.rb
new file mode 100644
index 000000000000..585b8f26a243
--- /dev/null
+++ b/google-cloud-spanner/test/google/cloud/spanner/client/resource_based_routing_test.rb
@@ -0,0 +1,137 @@
+# Copyright 2020 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.
+
+require "helper"
+
+describe Google::Cloud::Spanner::Client, :resource_based_routing, :mock_spanner do
+  let(:instance_id) { "my-instance-id" }
+  let(:database_id) { "my-database-id" }
+  let(:session_id) { "session123" }
+  let(:session_grpc) { Google::Spanner::V1::Session.new name: session_path(instance_id, database_id, session_id) }
+  let(:session) { Google::Cloud::Spanner::Session.from_grpc session_grpc, spanner.service }
+  let(:pool_opts) { { min: 0, max: 4 } }
+
+  before do
+    session.instance_variable_set :@last_updated_at, Time.now
+    ENV.delete "GOOGLE_CLOUD_SPANNER_ENABLE_RESOURCE_BASED_ROUTING"
+  end
+
+  after do
+    ENV.delete "GOOGLE_CLOUD_SPANNER_ENABLE_RESOURCE_BASED_ROUTING"
+  end
+
+
+  it "sets service with default host" do
+    client = Google::Cloud::Spanner::Client.new \
+      spanner, instance_id, database_id, pool_opts: { min: 0, max: 4 }
+
+    client.service.host.must_equal \
+      Google::Cloud::Spanner::V1::SpannerClient::SERVICE_ADDRESS
+    client.resource_based_routing_enabled?.must_equal false
+  end
+
+  it "sets service host to default service uri if resource based routing disabled" do
+    client = Google::Cloud::Spanner::Client.new \
+      spanner, instance_id, database_id, pool_opts: { min: 0, max: 4 },
+      enable_resource_based_routing: false
+
+    client.service.host.must_equal \
+      Google::Cloud::Spanner::V1::SpannerClient::SERVICE_ADDRESS
+    client.resource_based_routing_enabled?.must_equal false
+  end
+
+  it "set service host to instance endpoint uri if resource based routing enabled" do
+    get_res = Google::Spanner::Admin::Instance::V1::Instance.new \
+      name: instance_path(instance_id), endpoint_uris: ["test1.host.com", "test2.host.com"]
+    mock = Minitest::Mock.new
+    mock.expect :get_instance, get_res, [
+      instance_path(instance_id),
+      field_mask: Google::Protobuf::FieldMask.new(paths: ["endpoint_uris"])
+    ]
+    spanner.service.mocked_instances = mock
+
+    Google::Cloud::Spanner::Pool.stub :new, Object.new do
+      client = Google::Cloud::Spanner::Client.new \
+        spanner, instance_id, database_id, enable_resource_based_routing: true
+      client.resource_based_routing_enabled?.must_equal true
+      client.service.host.must_equal "test1.host.com"
+    end
+
+    mock.verify
+  end
+
+  it "set service host with instance endpoint uri if resource based routing enabled using an environment variable" do
+    ENV["GOOGLE_CLOUD_SPANNER_ENABLE_RESOURCE_BASED_ROUTING"] = "TRUE"
+
+    get_res = Google::Spanner::Admin::Instance::V1::Instance.new \
+      name: instance_path(instance_id), endpoint_uris: ["test1.host.com", "test2.host.com"]
+    mock = Minitest::Mock.new
+    mock.expect :get_instance, get_res, [
+      instance_path(instance_id),
+      field_mask: Google::Protobuf::FieldMask.new(paths: ["endpoint_uris"])
+    ]
+    spanner.service.mocked_instances = mock
+
+    Google::Cloud::Spanner::Pool.stub :new, Object.new do
+      client = Google::Cloud::Spanner::Client.new \
+        spanner, instance_id, database_id, enable_resource_based_routing: true
+      client.resource_based_routing_enabled?.must_equal true
+      client.service.host.must_equal "test1.host.com"
+    end
+
+    mock.verify
+  end
+
+  it "set default endpoint uri if resource based routing enabled and instance endpoint uris not present" do
+    get_res = Google::Spanner::Admin::Instance::V1::Instance.new \
+      name: instance_path(instance_id), endpoint_uris: []
+    mock = Minitest::Mock.new
+    mock.expect :get_instance, get_res, [
+      instance_path(instance_id),
+      field_mask: Google::Protobuf::FieldMask.new(paths: ["endpoint_uris"])
+    ]
+    spanner.service.mocked_instances = mock
+
+    Google::Cloud::Spanner::Pool.stub :new, Object.new do
+      client = Google::Cloud::Spanner::Client.new \
+        spanner, instance_id, database_id, enable_resource_based_routing: true
+      client.service.host.must_equal \
+        Google::Cloud::Spanner::V1::SpannerClient::SERVICE_ADDRESS
+      client.resource_based_routing_enabled?.must_equal true
+    end
+
+    mock.verify
+  end
+
+  it "returns default endpoint uri if get instance permission denied" do
+    stub = OpenStruct.new(api_call_count: 0)
+
+    def stub.get_instance *args
+      self.api_call_count += 1
+      raise Google::Cloud::Error.from_error(
+        GRPC::PermissionDenied.new "permission denied"
+      )
+    end
+    spanner.service.mocked_instances = stub
+
+    Google::Cloud::Spanner::Pool.stub :new, Object.new do
+      client = Google::Cloud::Spanner::Client.new \
+        spanner, instance_id, database_id, enable_resource_based_routing: true
+      client.service.host.must_equal \
+        Google::Cloud::Spanner::V1::SpannerClient::SERVICE_ADDRESS
+      stub.api_call_count.must_equal 1
+      client.resource_based_routing_enabled?.must_equal true
+    end
+  end
+end
diff --git a/google-cloud-spanner/test/google/cloud/spanner/instance_test.rb b/google-cloud-spanner/test/google/cloud/spanner/instance_test.rb
index e9054a712605..c4e95b6df898 100644
--- a/google-cloud-spanner/test/google/cloud/spanner/instance_test.rb
+++ b/google-cloud-spanner/test/google/cloud/spanner/instance_test.rb
@@ -27,5 +27,6 @@
     instance.state.must_equal :READY
     instance.must_be :ready?
     instance.wont_be :creating?
+    instance.endpoint_uris.must_be_empty
   end
 end
diff --git a/google-cloud-spanner/test/google/cloud/spanner/project/instance_test.rb b/google-cloud-spanner/test/google/cloud/spanner/project/instance_test.rb
index 73bd60dda43e..39fd4790ac3d 100644
--- a/google-cloud-spanner/test/google/cloud/spanner/project/instance_test.rb
+++ b/google-cloud-spanner/test/google/cloud/spanner/project/instance_test.rb
@@ -20,7 +20,7 @@
 
     get_res = Google::Spanner::Admin::Instance::V1::Instance.new instance_hash(name: instance_id)
     mock = Minitest::Mock.new
-    mock.expect :get_instance, get_res, [instance_path(instance_id)]
+    mock.expect :get_instance, get_res, [instance_path(instance_id), Hash]
     spanner.service.mocked_instances = mock
 
     instance = spanner.instance instance_id
@@ -48,4 +48,29 @@ def stub.get_instance *args
     instance = spanner.instance not_found_instance_id
     instance.must_be :nil?
   end
+
+  it "returns instance with provided fields" do
+    instance_id = "my-instance-id"
+
+    get_res = Google::Spanner::Admin::Instance::V1::Instance.new \
+      name: instance_path(instance_id), endpoint_uris: ["test.host.com"]
+    mock = Minitest::Mock.new
+    mock.expect :get_instance, get_res, [
+      instance_path(instance_id),
+      field_mask: Google::Protobuf::FieldMask.new(paths: ["name", "endpoint_uris"])
+    ]
+    spanner.service.mocked_instances = mock
+
+    instance = spanner.instance instance_id, fields: ["name", "endpoint_uris"]
+
+    mock.verify
+
+    instance.project_id.must_equal project
+    instance.instance_id.must_equal instance_id
+    instance.path.must_equal instance_path(instance_id)
+    instance.endpoint_uris.must_equal ["test.host.com"]
+    instance.name.must_equal ""
+    instance.node_count.must_equal 0
+    instance.state.must_equal :STATE_UNSPECIFIED
+  end
 end