diff --git a/vendor/google.golang.org/grpc/dialoptions.go b/vendor/google.golang.org/grpc/dialoptions.go
new file mode 100644
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+++ b/vendor/google.golang.org/grpc/dialoptions.go
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+/*
+ *
+ * Copyright 2018 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 (
+	"context"
+	"fmt"
+	"net"
+	"time"
+
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/backoff"
+	"google.golang.org/grpc/internal/envconfig"
+	"google.golang.org/grpc/internal/transport"
+	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/resolver"
+	"google.golang.org/grpc/stats"
+)
+
+// dialOptions configure a Dial call. dialOptions are set by the DialOption
+// values passed to Dial.
+type dialOptions struct {
+	unaryInt    UnaryClientInterceptor
+	streamInt   StreamClientInterceptor
+	cp          Compressor
+	dc          Decompressor
+	bs          backoff.Strategy
+	block       bool
+	insecure    bool
+	timeout     time.Duration
+	scChan      <-chan ServiceConfig
+	authority   string
+	copts       transport.ConnectOptions
+	callOptions []CallOption
+	// This is used by v1 balancer dial option WithBalancer to support v1
+	// balancer, and also by WithBalancerName dial option.
+	balancerBuilder balancer.Builder
+	// This is to support grpclb.
+	resolverBuilder      resolver.Builder
+	reqHandshake         envconfig.RequireHandshakeSetting
+	channelzParentID     int64
+	disableServiceConfig bool
+	disableRetry         bool
+	disableHealthCheck   bool
+}
+
+// DialOption configures how we set up the connection.
+type DialOption interface {
+	apply(*dialOptions)
+}
+
+// EmptyDialOption does not alter the dial configuration. It can be embedded in
+// another structure to build custom dial options.
+//
+// This API is EXPERIMENTAL.
+type EmptyDialOption struct{}
+
+func (EmptyDialOption) apply(*dialOptions) {}
+
+// funcDialOption wraps a function that modifies dialOptions into an
+// implementation of the DialOption interface.
+type funcDialOption struct {
+	f func(*dialOptions)
+}
+
+func (fdo *funcDialOption) apply(do *dialOptions) {
+	fdo.f(do)
+}
+
+func newFuncDialOption(f func(*dialOptions)) *funcDialOption {
+	return &funcDialOption{
+		f: f,
+	}
+}
+
+// WithWaitForHandshake blocks until the initial settings frame is received from
+// the server before assigning RPCs to the connection.
+//
+// Deprecated: this will become the default behavior in the 1.17 release, and
+// will be removed after the 1.18 release.  To override the default behavior in
+// the 1.17 release, either use this dial option or set the environment
+// variable GRPC_GO_READY_BEFORE_HANDSHAKE=on.
+func WithWaitForHandshake() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.reqHandshake = envconfig.RequireHandshakeOn
+	})
+}
+
+// WithWriteBufferSize determines how much data can be batched before doing a
+// write on the wire. The corresponding memory allocation for this buffer will
+// be twice the size to keep syscalls low. The default value for this buffer is
+// 32KB.
+//
+// Zero will disable the write buffer such that each write will be on underlying
+// connection. Note: A Send call may not directly translate to a write.
+func WithWriteBufferSize(s int) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.WriteBufferSize = s
+	})
+}
+
+// WithReadBufferSize lets you set the size of read buffer, this determines how
+// much data can be read at most for each read syscall.
+//
+// The default value for this buffer is 32KB. Zero will disable read buffer for
+// a connection so data framer can access the underlying conn directly.
+func WithReadBufferSize(s int) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.ReadBufferSize = s
+	})
+}
+
+// WithInitialWindowSize returns a DialOption which sets the value for initial
+// window size on a stream. The lower bound for window size is 64K and any value
+// smaller than that will be ignored.
+func WithInitialWindowSize(s int32) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.InitialWindowSize = s
+	})
+}
+
+// WithInitialConnWindowSize returns a DialOption which sets the value for
+// initial window size on a connection. The lower bound for window size is 64K
+// and any value smaller than that will be ignored.
+func WithInitialConnWindowSize(s int32) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.InitialConnWindowSize = s
+	})
+}
+
+// WithMaxMsgSize returns a DialOption which sets the maximum message size the
+// client can receive.
+//
+// Deprecated: use WithDefaultCallOptions(MaxCallRecvMsgSize(s)) instead.
+func WithMaxMsgSize(s int) DialOption {
+	return WithDefaultCallOptions(MaxCallRecvMsgSize(s))
+}
+
+// WithDefaultCallOptions returns a DialOption which sets the default
+// CallOptions for calls over the connection.
+func WithDefaultCallOptions(cos ...CallOption) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.callOptions = append(o.callOptions, cos...)
+	})
+}
+
+// WithCodec returns a DialOption which sets a codec for message marshaling and
+// unmarshaling.
+//
+// Deprecated: use WithDefaultCallOptions(CallCustomCodec(c)) instead.
+func WithCodec(c Codec) DialOption {
+	return WithDefaultCallOptions(CallCustomCodec(c))
+}
+
+// WithCompressor returns a DialOption which sets a Compressor to use for
+// message compression. It has lower priority than the compressor set by the
+// UseCompressor CallOption.
+//
+// Deprecated: use UseCompressor instead.
+func WithCompressor(cp Compressor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.cp = cp
+	})
+}
+
+// WithDecompressor returns a DialOption which sets a Decompressor to use for
+// incoming message decompression.  If incoming response messages are encoded
+// using the decompressor's Type(), it will be used.  Otherwise, the message
+// encoding will be used to look up the compressor registered via
+// encoding.RegisterCompressor, which will then be used to decompress the
+// message.  If no compressor is registered for the encoding, an Unimplemented
+// status error will be returned.
+//
+// Deprecated: use encoding.RegisterCompressor instead.
+func WithDecompressor(dc Decompressor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.dc = dc
+	})
+}
+
+// WithBalancer returns a DialOption which sets a load balancer with the v1 API.
+// Name resolver will be ignored if this DialOption is specified.
+//
+// Deprecated: use the new balancer APIs in balancer package and
+// WithBalancerName.
+func WithBalancer(b Balancer) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.balancerBuilder = &balancerWrapperBuilder{
+			b: b,
+		}
+	})
+}
+
+// WithBalancerName sets the balancer that the ClientConn will be initialized
+// with. Balancer registered with balancerName will be used. This function
+// panics if no balancer was registered by balancerName.
+//
+// The balancer cannot be overridden by balancer option specified by service
+// config.
+//
+// This is an EXPERIMENTAL API.
+func WithBalancerName(balancerName string) DialOption {
+	builder := balancer.Get(balancerName)
+	if builder == nil {
+		panic(fmt.Sprintf("grpc.WithBalancerName: no balancer is registered for name %v", balancerName))
+	}
+	return newFuncDialOption(func(o *dialOptions) {
+		o.balancerBuilder = builder
+	})
+}
+
+// withResolverBuilder is only for grpclb.
+func withResolverBuilder(b resolver.Builder) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.resolverBuilder = b
+	})
+}
+
+// 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
+func WithServiceConfig(c <-chan ServiceConfig) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.scChan = c
+	})
+}
+
+// WithBackoffMaxDelay configures the dialer to use the provided maximum delay
+// when backing off after failed connection attempts.
+func WithBackoffMaxDelay(md time.Duration) DialOption {
+	return WithBackoffConfig(BackoffConfig{MaxDelay: md})
+}
+
+// WithBackoffConfig configures the dialer to use the provided backoff
+// parameters after connection failures.
+//
+// Use WithBackoffMaxDelay until more parameters on BackoffConfig are opened up
+// for use.
+func WithBackoffConfig(b BackoffConfig) DialOption {
+	return withBackoff(backoff.Exponential{
+		MaxDelay: b.MaxDelay,
+	})
+}
+
+// withBackoff sets the backoff strategy used for connectRetryNum after a failed
+// connection attempt.
+//
+// This can be exported if arbitrary backoff strategies are allowed by gRPC.
+func withBackoff(bs backoff.Strategy) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.bs = bs
+	})
+}
+
+// WithBlock returns a DialOption which makes caller of Dial blocks until the
+// underlying connection is up. Without this, Dial returns immediately and
+// connecting the server happens in background.
+func WithBlock() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.block = true
+	})
+}
+
+// WithInsecure returns a DialOption which disables transport security for this
+// ClientConn. Note that transport security is required unless WithInsecure is
+// set.
+func WithInsecure() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.insecure = true
+	})
+}
+
+// WithTransportCredentials returns a DialOption which configures a connection
+// level security credentials (e.g., TLS/SSL). This should not be used together
+// with WithCredentialsBundle.
+func WithTransportCredentials(creds credentials.TransportCredentials) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.TransportCredentials = creds
+	})
+}
+
+// WithPerRPCCredentials returns a DialOption which sets credentials and places
+// auth state on each outbound RPC.
+func WithPerRPCCredentials(creds credentials.PerRPCCredentials) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.PerRPCCredentials = append(o.copts.PerRPCCredentials, creds)
+	})
+}
+
+// WithCredentialsBundle returns a DialOption to set a credentials bundle for
+// the ClientConn.WithCreds. This should not be used together with
+// WithTransportCredentials.
+//
+// This API is experimental.
+func WithCredentialsBundle(b credentials.Bundle) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.CredsBundle = b
+	})
+}
+
+// WithTimeout returns a DialOption that configures a timeout for dialing a
+// ClientConn initially. This is valid if and only if WithBlock() is present.
+//
+// Deprecated: use DialContext and context.WithTimeout instead.
+func WithTimeout(d time.Duration) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.timeout = d
+	})
+}
+
+func withContextDialer(f func(context.Context, string) (net.Conn, error)) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.Dialer = f
+	})
+}
+
+func init() {
+	internal.WithContextDialer = withContextDialer
+	internal.WithResolverBuilder = withResolverBuilder
+}
+
+// WithDialer returns a DialOption that specifies a function to use for dialing
+// network addresses. If FailOnNonTempDialError() is set to true, and an error
+// is returned by f, gRPC checks the error's Temporary() method to decide if it
+// should try to reconnect to the network address.
+func WithDialer(f func(string, time.Duration) (net.Conn, error)) DialOption {
+	return withContextDialer(
+		func(ctx context.Context, addr string) (net.Conn, error) {
+			if deadline, ok := ctx.Deadline(); ok {
+				return f(addr, deadline.Sub(time.Now()))
+			}
+			return f(addr, 0)
+		})
+}
+
+// WithStatsHandler returns a DialOption that specifies the stats handler for
+// all the RPCs and underlying network connections in this ClientConn.
+func WithStatsHandler(h stats.Handler) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.StatsHandler = h
+	})
+}
+
+// FailOnNonTempDialError returns a DialOption that specifies if gRPC fails on
+// non-temporary dial errors. If f is true, and dialer returns a non-temporary
+// error, gRPC will fail the connection to the network address and won't try to
+// reconnect. The default value of FailOnNonTempDialError is false.
+//
+// FailOnNonTempDialError only affects the initial dial, and does not do
+// anything useful unless you are also using WithBlock().
+//
+// This is an EXPERIMENTAL API.
+func FailOnNonTempDialError(f bool) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.FailOnNonTempDialError = f
+	})
+}
+
+// WithUserAgent returns a DialOption that specifies a user agent string for all
+// the RPCs.
+func WithUserAgent(s string) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.UserAgent = s
+	})
+}
+
+// WithKeepaliveParams returns a DialOption that specifies keepalive parameters
+// for the client transport.
+func WithKeepaliveParams(kp keepalive.ClientParameters) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.KeepaliveParams = kp
+	})
+}
+
+// WithUnaryInterceptor returns a DialOption that specifies the interceptor for
+// unary RPCs.
+func WithUnaryInterceptor(f UnaryClientInterceptor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.unaryInt = f
+	})
+}
+
+// WithStreamInterceptor returns a DialOption that specifies the interceptor for
+// streaming RPCs.
+func WithStreamInterceptor(f StreamClientInterceptor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.streamInt = f
+	})
+}
+
+// WithAuthority returns a DialOption that specifies the value to be used as the
+// :authority pseudo-header. This value only works with WithInsecure and has no
+// effect if TransportCredentials are present.
+func WithAuthority(a string) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.authority = a
+	})
+}
+
+// WithChannelzParentID returns a DialOption that specifies the channelz ID of
+// current ClientConn's parent. This function is used in nested channel creation
+// (e.g. grpclb dial).
+func WithChannelzParentID(id int64) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.channelzParentID = id
+	})
+}
+
+// WithDisableServiceConfig returns a DialOption that causes grpc to ignore any
+// service config provided by the resolver and provides a hint to the resolver
+// to not fetch service configs.
+func WithDisableServiceConfig() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.disableServiceConfig = true
+	})
+}
+
+// WithDisableRetry returns a DialOption that disables retries, even if the
+// service config enables them.  This does not impact transparent retries, which
+// will happen automatically if no data is written to the wire or if the RPC is
+// unprocessed by the remote server.
+//
+// Retry support is currently disabled by default, but will be enabled by
+// default in the future.  Until then, it may be enabled by setting the
+// environment variable "GRPC_GO_RETRY" to "on".
+//
+// This API is EXPERIMENTAL.
+func WithDisableRetry() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.disableRetry = true
+	})
+}
+
+// WithMaxHeaderListSize returns a DialOption that specifies the maximum
+// (uncompressed) size of header list that the client is prepared to accept.
+func WithMaxHeaderListSize(s uint32) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.MaxHeaderListSize = &s
+	})
+}
+
+// WithDisableHealthCheck disables the LB channel health checking for all SubConns of this ClientConn.
+//
+// This API is EXPERIMENTAL.
+func WithDisableHealthCheck() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.disableHealthCheck = true
+	})
+}
+func defaultDialOptions() dialOptions {
+	return dialOptions{
+		disableRetry: !envconfig.Retry,
+		reqHandshake: envconfig.RequireHandshake,
+		copts: transport.ConnectOptions{
+			WriteBufferSize: defaultWriteBufSize,
+			ReadBufferSize:  defaultReadBufSize,
+		},
+	}
+}