diff --git a/vendor/google.golang.org/grpc/resolver/resolver.go b/vendor/google.golang.org/grpc/resolver/resolver.go
new file mode 100644
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+++ b/vendor/google.golang.org/grpc/resolver/resolver.go
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+/*
+ *
+ * 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 resolver defines APIs for name resolution in gRPC.
+// All APIs in this package are experimental.
+package resolver
+
+import (
+	"google.golang.org/grpc/serviceconfig"
+)
+
+var (
+	// m is a map from scheme to resolver builder.
+	m = make(map[string]Builder)
+	// defaultScheme is the default scheme to use.
+	defaultScheme = "passthrough"
+)
+
+// TODO(bar) install dns resolver in init(){}.
+
+// Register registers the resolver builder to the resolver map. b.Scheme will be
+// used as the scheme registered with this builder.
+//
+// NOTE: this function must only be called during initialization time (i.e. in
+// an init() function), and is not thread-safe. If multiple Resolvers are
+// registered with the same name, the one registered last will take effect.
+func Register(b Builder) {
+	m[b.Scheme()] = b
+}
+
+// Get returns the resolver builder registered with the given scheme.
+//
+// If no builder is register with the scheme, nil will be returned.
+func Get(scheme string) Builder {
+	if b, ok := m[scheme]; ok {
+		return b
+	}
+	return nil
+}
+
+// SetDefaultScheme sets the default scheme that will be used. The default
+// default scheme is "passthrough".
+//
+// NOTE: this function must only be called during initialization time (i.e. in
+// an init() function), and is not thread-safe. The scheme set last overrides
+// previously set values.
+func SetDefaultScheme(scheme string) {
+	defaultScheme = scheme
+}
+
+// GetDefaultScheme gets the default scheme that will be used.
+func GetDefaultScheme() string {
+	return defaultScheme
+}
+
+// AddressType indicates the address type returned by name resolution.
+type AddressType uint8
+
+const (
+	// Backend indicates the address is for a backend server.
+	Backend AddressType = iota
+	// GRPCLB indicates the address is for a grpclb load balancer.
+	GRPCLB
+)
+
+// Address represents a server the client connects to.
+// This is the EXPERIMENTAL API and may be changed or extended in the future.
+type Address struct {
+	// Addr is the server address on which a connection will be established.
+	Addr string
+	// Type is the type of this address.
+	Type AddressType
+	// ServerName is the name of this address.
+	//
+	// e.g. if Type is GRPCLB, ServerName should be the name of the remote load
+	// balancer, not the name of the backend.
+	ServerName string
+	// Metadata is the information associated with Addr, which may be used
+	// to make load balancing decision.
+	Metadata interface{}
+}
+
+// BuildOption includes additional information for the builder to create
+// the resolver.
+type BuildOption struct {
+	// DisableServiceConfig indicates whether resolver should fetch service config data.
+	DisableServiceConfig bool
+}
+
+// State contains the current Resolver state relevant to the ClientConn.
+type State struct {
+	Addresses []Address // Resolved addresses for the target
+	// ServiceConfig is the parsed service config; obtained from
+	// serviceconfig.Parse.
+	ServiceConfig serviceconfig.Config
+
+	// TODO: add Err error
+}
+
+// ClientConn contains the callbacks for resolver to notify any updates
+// to the gRPC ClientConn.
+//
+// This interface is to be implemented by gRPC. Users should not need a
+// brand new implementation of this interface. For the situations like
+// testing, the new implementation should embed this interface. This allows
+// gRPC to add new methods to this interface.
+type ClientConn interface {
+	// UpdateState updates the state of the ClientConn appropriately.
+	UpdateState(State)
+	// NewAddress is called by resolver to notify ClientConn a new list
+	// of resolved addresses.
+	// The address list should be the complete list of resolved addresses.
+	//
+	// Deprecated: Use UpdateState instead.
+	NewAddress(addresses []Address)
+	// NewServiceConfig is called by resolver to notify ClientConn a new
+	// service config. The service config should be provided as a json string.
+	//
+	// Deprecated: Use UpdateState instead.
+	NewServiceConfig(serviceConfig string)
+}
+
+// Target represents a target for gRPC, as specified in:
+// https://github.com/grpc/grpc/blob/master/doc/naming.md.
+// It is parsed from the target string that gets passed into Dial or DialContext by the user. And
+// grpc passes it to the resolver and the balancer.
+//
+// If the target follows the naming spec, and the parsed scheme is registered with grpc, we will
+// parse the target string according to the spec. e.g. "dns://some_authority/foo.bar" will be parsed
+// into &Target{Scheme: "dns", Authority: "some_authority", Endpoint: "foo.bar"}
+//
+// If the target does not contain a scheme, we will apply the default scheme, and set the Target to
+// be the full target string. e.g. "foo.bar" will be parsed into
+// &Target{Scheme: resolver.GetDefaultScheme(), Endpoint: "foo.bar"}.
+//
+// If the parsed scheme is not registered (i.e. no corresponding resolver available to resolve the
+// endpoint), we set the Scheme to be the default scheme, and set the Endpoint to be the full target
+// string. e.g. target string "unknown_scheme://authority/endpoint" will be parsed into
+// &Target{Scheme: resolver.GetDefaultScheme(), Endpoint: "unknown_scheme://authority/endpoint"}.
+type Target struct {
+	Scheme    string
+	Authority string
+	Endpoint  string
+}
+
+// Builder creates a resolver that will be used to watch name resolution updates.
+type Builder interface {
+	// Build creates a new resolver for the given target.
+	//
+	// gRPC dial calls Build synchronously, and fails if the returned error is
+	// not nil.
+	Build(target Target, cc ClientConn, opts BuildOption) (Resolver, error)
+	// Scheme returns the scheme supported by this resolver.
+	// Scheme is defined at https://github.com/grpc/grpc/blob/master/doc/naming.md.
+	Scheme() string
+}
+
+// ResolveNowOption includes additional information for ResolveNow.
+type ResolveNowOption struct{}
+
+// Resolver watches for the updates on the specified target.
+// Updates include address updates and service config updates.
+type Resolver interface {
+	// ResolveNow will be called by gRPC to try to resolve the target name
+	// again. It's just a hint, resolver can ignore this if it's not necessary.
+	//
+	// It could be called multiple times concurrently.
+	ResolveNow(ResolveNowOption)
+	// Close closes the resolver.
+	Close()
+}
+
+// UnregisterForTesting removes the resolver builder with the given scheme from the
+// resolver map.
+// This function is for testing only.
+func UnregisterForTesting(scheme string) {
+	delete(m, scheme)
+}