Add WithResolverUserOptions for custom resolver build options (#1711)

clientconn.go

@@ -99,6 +99,8 @@ type dialOptions struct {
 	balancerBuilder balancer.Builder
 	// This is to support grpclb.
 	resolverBuilder resolver.Builder
+	// Custom user options for resolver.Build.
+	resolverBuildUserOptions interface{}
 	waitForHandshake         bool
 }
 
@@ -223,6 +225,14 @@ func withResolverBuilder(b resolver.Builder) DialOption {
 	}
 }
 
+// WithResolverUserOptions returns a DialOption which sets the UserOptions
+// field of resolver's BuildOption.
+func WithResolverUserOptions(userOpt interface{}) DialOption {
+	return func(o *dialOptions) {
+		o.resolverBuildUserOptions = userOpt
+	}
+}
+
 // WithServiceConfig returns a DialOption which has a channel to read the service configuration.
 // DEPRECATED: service config should be received through name resolver, as specified here.
 // https://github.com/grpc/grpc/blob/master/doc/service_config.md

clientconn_test.go

@@ -583,41 +583,6 @@ func TestNonblockingDialWithEmptyBalancer(t *testing.T) {
 	}
 }
 
-func TestResolverServiceConfigBeforeAddressNotPanic(t *testing.T) {
-	defer leakcheck.Check(t)
-	r, rcleanup := manual.GenerateAndRegisterManualResolver()
-	defer rcleanup()
-
-	cc, err := Dial(r.Scheme()+":///test.server", WithInsecure())
-	if err != nil {
-		t.Fatalf("failed to dial: %v", err)
-	}
-	defer cc.Close()
-
-	// SwitchBalancer before NewAddress. There was no balancer created, this
-	// makes sure we don't call close on nil balancerWrapper.
-	r.NewServiceConfig(`{"loadBalancingPolicy": "round_robin"}`) // This should not panic.
-
-	time.Sleep(time.Second) // Sleep to make sure the service config is handled by ClientConn.
-}
-
-func TestResolverEmptyUpdateNotPanic(t *testing.T) {
-	defer leakcheck.Check(t)
-	r, rcleanup := manual.GenerateAndRegisterManualResolver()
-	defer rcleanup()
-
-	cc, err := Dial(r.Scheme()+":///test.server", WithInsecure())
-	if err != nil {
-		t.Fatalf("failed to dial: %v", err)
-	}
-	defer cc.Close()
-
-	// This make sure we don't create addrConn with empty address list.
-	r.NewAddress([]resolver.Address{}) // This should not panic.
-
-	time.Sleep(time.Second) // Sleep to make sure the service config is handled by ClientConn.
-}
-
 func TestClientUpdatesParamsAfterGoAway(t *testing.T) {
 	defer leakcheck.Check(t)
 	lis, err := net.Listen("tcp", "localhost:0")

resolver/resolver.go

@@ -90,6 +90,9 @@ type Address struct {
 // BuildOption includes additional information for the builder to create
 // the resolver.
 type BuildOption struct {
+	// UserOptions can be used to pass configuration between DialOptions and the
+	// resolver.
+	UserOptions interface{}
 }
 
 // ClientConn contains the callbacks for resolver to notify any updates

resolver_conn_wrapper.go

@@ -83,7 +83,9 @@ func newCCResolverWrapper(cc *ClientConn) (*ccResolverWrapper, error) {
 	}
 
 	var err error
-	ccr.resolver, err = rb.Build(cc.parsedTarget, ccr, resolver.BuildOption{})
+	ccr.resolver, err = rb.Build(cc.parsedTarget, ccr, resolver.BuildOption{
+		UserOptions: cc.dopts.resolverBuildUserOptions,
+	})
 	if err != nil {
 		return nil, err
 	}

resolver_test.go

@@ -0,0 +1,99 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * 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.
+ *
+ */
+
+package grpc
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"google.golang.org/grpc/resolver"
+	"google.golang.org/grpc/resolver/manual"
+	"google.golang.org/grpc/test/leakcheck"
+)
+
+func TestResolverServiceConfigBeforeAddressNotPanic(t *testing.T) {
+	defer leakcheck.Check(t)
+	r, rcleanup := manual.GenerateAndRegisterManualResolver()
+	defer rcleanup()
+
+	cc, err := Dial(r.Scheme()+":///test.server", WithInsecure())
+	if err != nil {
+		t.Fatalf("failed to dial: %v", err)
+	}
+	defer cc.Close()
+
+	// SwitchBalancer before NewAddress. There was no balancer created, this
+	// makes sure we don't call close on nil balancerWrapper.
+	r.NewServiceConfig(`{"loadBalancingPolicy": "round_robin"}`) // This should not panic.
+
+	time.Sleep(time.Second) // Sleep to make sure the service config is handled by ClientConn.
+}
+
+func TestResolverEmptyUpdateNotPanic(t *testing.T) {
+	defer leakcheck.Check(t)
+	r, rcleanup := manual.GenerateAndRegisterManualResolver()
+	defer rcleanup()
+
+	cc, err := Dial(r.Scheme()+":///test.server", WithInsecure())
+	if err != nil {
+		t.Fatalf("failed to dial: %v", err)
+	}
+	defer cc.Close()
+
+	// This make sure we don't create addrConn with empty address list.
+	r.NewAddress([]resolver.Address{}) // This should not panic.
+
+	time.Sleep(time.Second) // Sleep to make sure the service config is handled by ClientConn.
+}
+
+var (
+	errTestResolverFailBuild = fmt.Errorf("test resolver build error")
+)
+
+type testResolverFailBuilder struct {
+	buildOpt resolver.BuildOption
+}
+
+func (r *testResolverFailBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOption) (resolver.Resolver, error) {
+	r.buildOpt = opts
+	return nil, errTestResolverFailBuild
+}
+func (r *testResolverFailBuilder) Scheme() string {
+	return "testResolverFailBuilderScheme"
+}
+
+// Tests that options in WithResolverUserOptions are passed to resolver.Build().
+func TestResolverUserOptions(t *testing.T) {
+	r := &testResolverFailBuilder{}
+
+	userOpt := "testUserOpt"
+	_, err := Dial("scheme:///test.server", WithInsecure(),
+		withResolverBuilder(r),
+		WithResolverUserOptions(userOpt),
+	)
+	if err == nil || !strings.Contains(err.Error(), errTestResolverFailBuild.Error()) {
+		t.Fatalf("Dial with testResolverFailBuilder returns err: %v, want: %v", err, errTestResolverFailBuild)
+	}
+
+	if r.buildOpt.UserOptions != userOpt {
+		t.Fatalf("buildOpt.UserOptions = %T %+v, want %v", r.buildOpt.UserOptions, r.buildOpt.UserOptions, userOpt)
+	}
+}