Add AdditionalDialOptions to ConnBuilder (#3865)

Signed-off-by: Prithvi Raj <p.r@uber.com>

Signed-off-by: Prithvi Raj <p.r@uber.com>

cmd/agent/app/reporter/grpc/builder.go

@@ -47,6 +47,8 @@ type ConnBuilder struct {
 	DiscoveryMinPeers int
 	Notifier          discovery.Notifier
 	Discoverer        discovery.Discoverer
+
+	AdditionalDialOptions []grpc.DialOption
 }
 
 // NewConnBuilder creates a new grpc connection builder.
@@ -96,6 +98,8 @@ func (b *ConnBuilder) CreateConnection(logger *zap.Logger, mFactory metrics.Fact
 	}
 	dialOptions = append(dialOptions, grpc.WithDefaultServiceConfig(grpcresolver.GRPCServiceConfig))
 	dialOptions = append(dialOptions, grpc.WithUnaryInterceptor(grpc_retry.UnaryClientInterceptor(grpc_retry.WithMax(b.MaxRetry))))
+	dialOptions = append(dialOptions, b.AdditionalDialOptions...)
+
 	conn, err := grpc.Dial(dialTarget, dialOptions...)
 	if err != nil {
 		return nil, err

cmd/agent/app/reporter/grpc/builder_test.go

@@ -395,3 +395,33 @@ func assertConnectionState(t *testing.T, conn *grpc.ClientConn, expectedState st
 		}
 	}
 }
+
+type fakeInterceptor struct {
+	isCalled bool
+}
+
+func (f *fakeInterceptor) intercept(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+	f.isCalled = true
+	return invoker(ctx, method, req, reply, cc, opts...)
+}
+
+func (f *fakeInterceptor) assertCalled(t *testing.T) {
+	assert.True(t, f.isCalled)
+}
+
+func TestBuilderWithAdditionalDialOptions(t *testing.T) {
+	fi := fakeInterceptor{}
+	defer fi.assertCalled(t)
+
+	cb := ConnBuilder{
+		CollectorHostPorts:    []string{"127.0.0.1:14268"},
+		AdditionalDialOptions: []grpc.DialOption{grpc.WithUnaryInterceptor(fi.intercept)},
+	}
+
+	r, err := cb.CreateConnection(zap.NewNop(), metrics.NullFactory)
+	require.NoError(t, err)
+	assert.NotNil(t, r)
+
+	err = r.Invoke(context.Background(), "test", map[string]string{}, map[string]string{}, []grpc.CallOption{}...)
+	assert.Error(t, err, "should error because no server is running")
+}