Update dependencies

16 files changed, 1732 insertions, 0 deletions

diff --git a/vendor/go.opencensus.io/plugin/ocgrpc/client.go b/vendor/go.opencensus.io/plugin/ocgrpc/client.go
new file mode 100644
index 0000000..a6c466a
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ocgrpc/client.go
@@ -0,0 +1,56 @@
+// Copyright 2018, OpenCensus 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 ocgrpc
+
+import (
+	"go.opencensus.io/trace"
+	"golang.org/x/net/context"
+
+	"google.golang.org/grpc/stats"
+)
+
+// ClientHandler implements a gRPC stats.Handler for recording OpenCensus stats and
+// traces. Use with gRPC clients only.
+type ClientHandler struct {
+	// StartOptions allows configuring the StartOptions used to create new spans.
+	//
+	// StartOptions.SpanKind will always be set to trace.SpanKindClient
+	// for spans started by this handler.
+	StartOptions trace.StartOptions
+}
+
+// HandleConn exists to satisfy gRPC stats.Handler.
+func (c *ClientHandler) HandleConn(ctx context.Context, cs stats.ConnStats) {
+	// no-op
+}
+
+// TagConn exists to satisfy gRPC stats.Handler.
+func (c *ClientHandler) TagConn(ctx context.Context, cti *stats.ConnTagInfo) context.Context {
+	// no-op
+	return ctx
+}
+
+// HandleRPC implements per-RPC tracing and stats instrumentation.
+func (c *ClientHandler) HandleRPC(ctx context.Context, rs stats.RPCStats) {
+	traceHandleRPC(ctx, rs)
+	statsHandleRPC(ctx, rs)
+}
+
+// TagRPC implements per-RPC context management.
+func (c *ClientHandler) TagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	ctx = c.traceTagRPC(ctx, rti)
+	ctx = c.statsTagRPC(ctx, rti)
+	return ctx
+}
diff --git a/vendor/go.opencensus.io/plugin/ocgrpc/client_metrics.go b/vendor/go.opencensus.io/plugin/ocgrpc/client_metrics.go
new file mode 100644
index 0000000..b8efacf
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ocgrpc/client_metrics.go
@@ -0,0 +1,116 @@
+// Copyright 2017, OpenCensus 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 ocgrpc
+
+import (
+	"go.opencensus.io/stats"
+	"go.opencensus.io/stats/view"
+	"go.opencensus.io/tag"
+)
+
+// The following variables are measures are recorded by ClientHandler:
+var (
+	ClientSentMessagesPerRPC     = stats.Int64("grpc.io/client/sent_messages_per_rpc", "Number of messages sent in the RPC (always 1 for non-streaming RPCs).", stats.UnitDimensionless)
+	ClientSentBytesPerRPC        = stats.Int64("grpc.io/client/sent_bytes_per_rpc", "Total bytes sent across all request messages per RPC.", stats.UnitBytes)
+	ClientReceivedMessagesPerRPC = stats.Int64("grpc.io/client/received_messages_per_rpc", "Number of response messages received per RPC (always 1 for non-streaming RPCs).", stats.UnitDimensionless)
+	ClientReceivedBytesPerRPC    = stats.Int64("grpc.io/client/received_bytes_per_rpc", "Total bytes received across all response messages per RPC.", stats.UnitBytes)
+	ClientRoundtripLatency       = stats.Float64("grpc.io/client/roundtrip_latency", "Time between first byte of request sent to last byte of response received, or terminal error.", stats.UnitMilliseconds)
+	ClientServerLatency          = stats.Float64("grpc.io/client/server_latency", `Propagated from the server and should have the same value as "grpc.io/server/latency".`, stats.UnitMilliseconds)
+)
+
+// Predefined views may be subscribed to collect data for the above measures.
+// As always, you may also define your own custom views over measures collected by this
+// package. These are declared as a convenience only; none are subscribed by
+// default.
+var (
+	ClientSentBytesPerRPCView = &view.View{
+		Measure:     ClientSentBytesPerRPC,
+		Name:        "grpc.io/client/sent_bytes_per_rpc",
+		Description: "Distribution of bytes sent per RPC, by method.",
+		TagKeys:     []tag.Key{KeyClientMethod},
+		Aggregation: DefaultBytesDistribution,
+	}
+
+	ClientReceivedBytesPerRPCView = &view.View{
+		Measure:     ClientReceivedBytesPerRPC,
+		Name:        "grpc.io/client/received_bytes_per_rpc",
+		Description: "Distribution of bytes received per RPC, by method.",
+		TagKeys:     []tag.Key{KeyClientMethod},
+		Aggregation: DefaultBytesDistribution,
+	}
+
+	ClientRoundtripLatencyView = &view.View{
+		Measure:     ClientRoundtripLatency,
+		Name:        "grpc.io/client/roundtrip_latency",
+		Description: "Distribution of round-trip latency, by method.",
+		TagKeys:     []tag.Key{KeyClientMethod},
+		Aggregation: DefaultMillisecondsDistribution,
+	}
+
+	ClientCompletedRPCsView = &view.View{
+		Measure:     ClientRoundtripLatency,
+		Name:        "grpc.io/client/completed_rpcs",
+		Description: "Count of RPCs by method and status.",
+		TagKeys:     []tag.Key{KeyClientMethod, KeyClientStatus},
+		Aggregation: view.Count(),
+	}
+
+	ClientSentMessagesPerRPCView = &view.View{
+		Measure:     ClientSentMessagesPerRPC,
+		Name:        "grpc.io/client/sent_messages_per_rpc",
+		Description: "Distribution of sent messages count per RPC, by method.",
+		TagKeys:     []tag.Key{KeyClientMethod},
+		Aggregation: DefaultMessageCountDistribution,
+	}
+
+	ClientReceivedMessagesPerRPCView = &view.View{
+		Measure:     ClientReceivedMessagesPerRPC,
+		Name:        "grpc.io/client/received_messages_per_rpc",
+		Description: "Distribution of received messages count per RPC, by method.",
+		TagKeys:     []tag.Key{KeyClientMethod},
+		Aggregation: DefaultMessageCountDistribution,
+	}
+
+	ClientServerLatencyView = &view.View{
+		Measure:     ClientServerLatency,
+		Name:        "grpc.io/client/server_latency",
+		Description: "Distribution of server latency as viewed by client, by method.",
+		TagKeys:     []tag.Key{KeyClientMethod},
+		Aggregation: DefaultMillisecondsDistribution,
+	}
+
+	// Deprecated: This view is going to be removed, if you need it please define it
+	// yourself.
+	ClientRequestCountView = &view.View{
+		Name:        "Count of request messages per client RPC",
+		TagKeys:     []tag.Key{KeyClientMethod},
+		Measure:     ClientRoundtripLatency,
+		Aggregation: view.Count(),
+	}
+)
+
+// DefaultClientViews are the default client views provided by this package.
+var DefaultClientViews = []*view.View{
+	ClientSentBytesPerRPCView,
+	ClientReceivedBytesPerRPCView,
+	ClientRoundtripLatencyView,
+	ClientCompletedRPCsView,
+}
+
+// TODO(jbd): Add roundtrip_latency, uncompressed_request_bytes, uncompressed_response_bytes, request_count, response_count.
+// TODO(acetechnologist): This is temporary and will need to be replaced by a
+// mechanism to load these defaults from a common repository/config shared by
+// all supported languages. Likely a serialized protobuf of these defaults.
diff --git a/vendor/go.opencensus.io/plugin/ocgrpc/client_stats_handler.go b/vendor/go.opencensus.io/plugin/ocgrpc/client_stats_handler.go
new file mode 100644
index 0000000..303c607
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ocgrpc/client_stats_handler.go
@@ -0,0 +1,49 @@
+// Copyright 2017, OpenCensus 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 ocgrpc
+
+import (
+	"time"
+
+	"go.opencensus.io/tag"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/stats"
+)
+
+// statsTagRPC gets the tag.Map populated by the application code, serializes
+// its tags into the GRPC metadata in order to be sent to the server.
+func (h *ClientHandler) statsTagRPC(ctx context.Context, info *stats.RPCTagInfo) context.Context {
+	startTime := time.Now()
+	if info == nil {
+		if grpclog.V(2) {
+			grpclog.Infof("clientHandler.TagRPC called with nil info.", info.FullMethodName)
+		}
+		return ctx
+	}
+
+	d := &rpcData{
+		startTime: startTime,
+		method:    info.FullMethodName,
+	}
+	ts := tag.FromContext(ctx)
+	if ts != nil {
+		encoded := tag.Encode(ts)
+		ctx = stats.SetTags(ctx, encoded)
+	}
+
+	return context.WithValue(ctx, rpcDataKey, d)
+}
diff --git a/vendor/go.opencensus.io/plugin/ocgrpc/doc.go b/vendor/go.opencensus.io/plugin/ocgrpc/doc.go
new file mode 100644
index 0000000..1370323
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ocgrpc/doc.go
@@ -0,0 +1,19 @@
+// Copyright 2017, OpenCensus 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 ocgrpc contains OpenCensus stats and trace
+// integrations for gRPC.
+//
+// Use ServerHandler for servers and ClientHandler for clients.
+package ocgrpc // import "go.opencensus.io/plugin/ocgrpc"
diff --git a/vendor/go.opencensus.io/plugin/ocgrpc/server.go b/vendor/go.opencensus.io/plugin/ocgrpc/server.go
new file mode 100644
index 0000000..b67b3e2
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ocgrpc/server.go
@@ -0,0 +1,80 @@
+// Copyright 2018, OpenCensus 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 ocgrpc
+
+import (
+	"go.opencensus.io/trace"
+	"golang.org/x/net/context"
+
+	"google.golang.org/grpc/stats"
+)
+
+// ServerHandler implements gRPC stats.Handler recording OpenCensus stats and
+// traces. Use with gRPC servers.
+//
+// When installed (see Example), tracing metadata is read from inbound RPCs
+// by default. If no tracing metadata is present, or if the tracing metadata is
+// present but the SpanContext isn't sampled, then a new trace may be started
+// (as determined by Sampler).
+type ServerHandler struct {
+	// IsPublicEndpoint may be set to true to always start a new trace around
+	// each RPC. Any SpanContext in the RPC metadata will be added as a linked
+	// span instead of making it the parent of the span created around the
+	// server RPC.
+	//
+	// Be aware that if you leave this false (the default) on a public-facing
+	// server, callers will be able to send tracing metadata in gRPC headers
+	// and trigger traces in your backend.
+	IsPublicEndpoint bool
+
+	// StartOptions to use for to spans started around RPCs handled by this server.
+	//
+	// These will apply even if there is tracing metadata already
+	// present on the inbound RPC but the SpanContext is not sampled. This
+	// ensures that each service has some opportunity to be traced. If you would
+	// like to not add any additional traces for this gRPC service, set:
+	//
+	//   StartOptions.Sampler = trace.ProbabilitySampler(0.0)
+	//
+	// StartOptions.SpanKind will always be set to trace.SpanKindServer
+	// for spans started by this handler.
+	StartOptions trace.StartOptions
+}
+
+var _ stats.Handler = (*ServerHandler)(nil)
+
+// HandleConn exists to satisfy gRPC stats.Handler.
+func (s *ServerHandler) HandleConn(ctx context.Context, cs stats.ConnStats) {
+	// no-op
+}
+
+// TagConn exists to satisfy gRPC stats.Handler.
+func (s *ServerHandler) TagConn(ctx context.Context, cti *stats.ConnTagInfo) context.Context {
+	// no-op
+	return ctx
+}
+
+// HandleRPC implements per-RPC tracing and stats instrumentation.
+func (s *ServerHandler) HandleRPC(ctx context.Context, rs stats.RPCStats) {
+	traceHandleRPC(ctx, rs)
+	statsHandleRPC(ctx, rs)
+}
+
+// TagRPC implements per-RPC context management.
+func (s *ServerHandler) TagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	ctx = s.traceTagRPC(ctx, rti)
+	ctx = s.statsTagRPC(ctx, rti)
+	return ctx
+}
diff --git a/vendor/go.opencensus.io/plugin/ocgrpc/server_metrics.go b/vendor/go.opencensus.io/plugin/ocgrpc/server_metrics.go
new file mode 100644
index 0000000..02323f8
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ocgrpc/server_metrics.go
@@ -0,0 +1,97 @@
+// Copyright 2017, OpenCensus 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 ocgrpc
+
+import (
+	"go.opencensus.io/stats"
+	"go.opencensus.io/stats/view"
+	"go.opencensus.io/tag"
+)
+
+// The following variables are measures are recorded by ServerHandler:
+var (
+	ServerReceivedMessagesPerRPC = stats.Int64("grpc.io/server/received_messages_per_rpc", "Number of messages received in each RPC. Has value 1 for non-streaming RPCs.", stats.UnitDimensionless)
+	ServerReceivedBytesPerRPC    = stats.Int64("grpc.io/server/received_bytes_per_rpc", "Total bytes received across all messages per RPC.", stats.UnitBytes)
+	ServerSentMessagesPerRPC     = stats.Int64("grpc.io/server/sent_messages_per_rpc", "Number of messages sent in each RPC. Has value 1 for non-streaming RPCs.", stats.UnitDimensionless)
+	ServerSentBytesPerRPC        = stats.Int64("grpc.io/server/sent_bytes_per_rpc", "Total bytes sent in across all response messages per RPC.", stats.UnitBytes)
+	ServerLatency                = stats.Float64("grpc.io/server/server_latency", "Time between first byte of request received to last byte of response sent, or terminal error.", stats.UnitMilliseconds)
+)
+
+// TODO(acetechnologist): This is temporary and will need to be replaced by a
+// mechanism to load these defaults from a common repository/config shared by
+// all supported languages. Likely a serialized protobuf of these defaults.
+
+// Predefined views may be subscribed to collect data for the above measures.
+// As always, you may also define your own custom views over measures collected by this
+// package. These are declared as a convenience only; none are subscribed by
+// default.
+var (
+	ServerReceivedBytesPerRPCView = &view.View{
+		Name:        "grpc.io/server/received_bytes_per_rpc",
+		Description: "Distribution of received bytes per RPC, by method.",
+		Measure:     ServerReceivedBytesPerRPC,
+		TagKeys:     []tag.Key{KeyServerMethod},
+		Aggregation: DefaultBytesDistribution,
+	}
+
+	ServerSentBytesPerRPCView = &view.View{
+		Name:        "grpc.io/server/sent_bytes_per_rpc",
+		Description: "Distribution of total sent bytes per RPC, by method.",
+		Measure:     ServerSentBytesPerRPC,
+		TagKeys:     []tag.Key{KeyServerMethod},
+		Aggregation: DefaultBytesDistribution,
+	}
+
+	ServerLatencyView = &view.View{
+		Name:        "grpc.io/server/server_latency",
+		Description: "Distribution of server latency in milliseconds, by method.",
+		TagKeys:     []tag.Key{KeyServerMethod},
+		Measure:     ServerLatency,
+		Aggregation: DefaultMillisecondsDistribution,
+	}
+
+	ServerCompletedRPCsView = &view.View{
+		Name:        "grpc.io/server/completed_rpcs",
+		Description: "Count of RPCs by method and status.",
+		TagKeys:     []tag.Key{KeyServerMethod, KeyServerStatus},
+		Measure:     ServerLatency,
+		Aggregation: view.Count(),
+	}
+
+	ServerReceivedMessagesPerRPCView = &view.View{
+		Name:        "grpc.io/server/received_messages_per_rpc",
+		Description: "Distribution of messages received count per RPC, by method.",
+		TagKeys:     []tag.Key{KeyServerMethod},
+		Measure:     ServerReceivedMessagesPerRPC,
+		Aggregation: DefaultMessageCountDistribution,
+	}
+
+	ServerSentMessagesPerRPCView = &view.View{
+		Name:        "grpc.io/server/sent_messages_per_rpc",
+		Description: "Distribution of messages sent count per RPC, by method.",
+		TagKeys:     []tag.Key{KeyServerMethod},
+		Measure:     ServerSentMessagesPerRPC,
+		Aggregation: DefaultMessageCountDistribution,
+	}
+)
+
+// DefaultServerViews are the default server views provided by this package.
+var DefaultServerViews = []*view.View{
+	ServerReceivedBytesPerRPCView,
+	ServerSentBytesPerRPCView,
+	ServerLatencyView,
+	ServerCompletedRPCsView,
+}
diff --git a/vendor/go.opencensus.io/plugin/ocgrpc/server_stats_handler.go b/vendor/go.opencensus.io/plugin/ocgrpc/server_stats_handler.go
new file mode 100644
index 0000000..7847c1a
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ocgrpc/server_stats_handler.go
@@ -0,0 +1,63 @@
+// Copyright 2017, OpenCensus 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 ocgrpc
+
+import (
+	"time"
+
+	"golang.org/x/net/context"
+
+	"go.opencensus.io/tag"
+	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/stats"
+)
+
+// statsTagRPC gets the metadata from gRPC context, extracts the encoded tags from
+// it and creates a new tag.Map and puts them into the returned context.
+func (h *ServerHandler) statsTagRPC(ctx context.Context, info *stats.RPCTagInfo) context.Context {
+	startTime := time.Now()
+	if info == nil {
+		if grpclog.V(2) {
+			grpclog.Infof("opencensus: TagRPC called with nil info.")
+		}
+		return ctx
+	}
+	d := &rpcData{
+		startTime: startTime,
+		method:    info.FullMethodName,
+	}
+	propagated := h.extractPropagatedTags(ctx)
+	ctx = tag.NewContext(ctx, propagated)
+	ctx, _ = tag.New(ctx, tag.Upsert(KeyServerMethod, methodName(info.FullMethodName)))
+	return context.WithValue(ctx, rpcDataKey, d)
+}
+
+// extractPropagatedTags creates a new tag map containing the tags extracted from the
+// gRPC metadata.
+func (h *ServerHandler) extractPropagatedTags(ctx context.Context) *tag.Map {
+	buf := stats.Tags(ctx)
+	if buf == nil {
+		return nil
+	}
+	propagated, err := tag.Decode(buf)
+	if err != nil {
+		if grpclog.V(2) {
+			grpclog.Warningf("opencensus: Failed to decode tags from gRPC metadata failed to decode: %v", err)
+		}
+		return nil
+	}
+	return propagated
+}
diff --git a/vendor/go.opencensus.io/plugin/ocgrpc/stats_common.go b/vendor/go.opencensus.io/plugin/ocgrpc/stats_common.go
new file mode 100644
index 0000000..119bbda
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ocgrpc/stats_common.go
@@ -0,0 +1,205 @@
+// Copyright 2017, OpenCensus 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 ocgrpc
+
+import (
+	"context"
+	"strconv"
+	"strings"
+	"sync/atomic"
+	"time"
+
+	ocstats "go.opencensus.io/stats"
+	"go.opencensus.io/stats/view"
+	"go.opencensus.io/tag"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+)
+
+type grpcInstrumentationKey string
+
+// rpcData holds the instrumentation RPC data that is needed between the start
+// and end of an call. It holds the info that this package needs to keep track
+// of between the various GRPC events.
+type rpcData struct {
+	// reqCount and respCount has to be the first words
+	// in order to be 64-aligned on 32-bit architectures.
+	sentCount, sentBytes, recvCount, recvBytes int64 // access atomically
+
+	// startTime represents the time at which TagRPC was invoked at the
+	// beginning of an RPC. It is an appoximation of the time when the
+	// application code invoked GRPC code.
+	startTime time.Time
+	method    string
+}
+
+// The following variables define the default hard-coded auxiliary data used by
+// both the default GRPC client and GRPC server metrics.
+var (
+	DefaultBytesDistribution        = view.Distribution(0, 1024, 2048, 4096, 16384, 65536, 262144, 1048576, 4194304, 16777216, 67108864, 268435456, 1073741824, 4294967296)
+	DefaultMillisecondsDistribution = view.Distribution(0, 0.01, 0.05, 0.1, 0.3, 0.6, 0.8, 1, 2, 3, 4, 5, 6, 8, 10, 13, 16, 20, 25, 30, 40, 50, 65, 80, 100, 130, 160, 200, 250, 300, 400, 500, 650, 800, 1000, 2000, 5000, 10000, 20000, 50000, 100000)
+	DefaultMessageCountDistribution = view.Distribution(0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536)
+)
+
+// Server tags are applied to the context used to process each RPC, as well as
+// the measures at the end of each RPC.
+var (
+	KeyServerMethod, _ = tag.NewKey("grpc_server_method")
+	KeyServerStatus, _ = tag.NewKey("grpc_server_status")
+)
+
+// Client tags are applied to measures at the end of each RPC.
+var (
+	KeyClientMethod, _ = tag.NewKey("grpc_client_method")
+	KeyClientStatus, _ = tag.NewKey("grpc_client_status")
+)
+
+var (
+	rpcDataKey = grpcInstrumentationKey("opencensus-rpcData")
+)
+
+func methodName(fullname string) string {
+	return strings.TrimLeft(fullname, "/")
+}
+
+// statsHandleRPC processes the RPC events.
+func statsHandleRPC(ctx context.Context, s stats.RPCStats) {
+	switch st := s.(type) {
+	case *stats.Begin, *stats.OutHeader, *stats.InHeader, *stats.InTrailer, *stats.OutTrailer:
+		// do nothing for client
+	case *stats.OutPayload:
+		handleRPCOutPayload(ctx, st)
+	case *stats.InPayload:
+		handleRPCInPayload(ctx, st)
+	case *stats.End:
+		handleRPCEnd(ctx, st)
+	default:
+		grpclog.Infof("unexpected stats: %T", st)
+	}
+}
+
+func handleRPCOutPayload(ctx context.Context, s *stats.OutPayload) {
+	d, ok := ctx.Value(rpcDataKey).(*rpcData)
+	if !ok {
+		if grpclog.V(2) {
+			grpclog.Infoln("Failed to retrieve *rpcData from context.")
+		}
+		return
+	}
+
+	atomic.AddInt64(&d.sentBytes, int64(s.Length))
+	atomic.AddInt64(&d.sentCount, 1)
+}
+
+func handleRPCInPayload(ctx context.Context, s *stats.InPayload) {
+	d, ok := ctx.Value(rpcDataKey).(*rpcData)
+	if !ok {
+		if grpclog.V(2) {
+			grpclog.Infoln("Failed to retrieve *rpcData from context.")
+		}
+		return
+	}
+
+	atomic.AddInt64(&d.recvBytes, int64(s.Length))
+	atomic.AddInt64(&d.recvCount, 1)
+}
+
+func handleRPCEnd(ctx context.Context, s *stats.End) {
+	d, ok := ctx.Value(rpcDataKey).(*rpcData)
+	if !ok {
+		if grpclog.V(2) {
+			grpclog.Infoln("Failed to retrieve *rpcData from context.")
+		}
+		return
+	}
+
+	elapsedTime := time.Since(d.startTime)
+
+	var st string
+	if s.Error != nil {
+		s, ok := status.FromError(s.Error)
+		if ok {
+			st = statusCodeToString(s)
+		}
+	} else {
+		st = "OK"
+	}
+
+	latencyMillis := float64(elapsedTime) / float64(time.Millisecond)
+	if s.Client {
+		ctx, _ = tag.New(ctx,
+			tag.Upsert(KeyClientMethod, methodName(d.method)),
+			tag.Upsert(KeyClientStatus, st))
+		ocstats.Record(ctx,
+			ClientSentBytesPerRPC.M(atomic.LoadInt64(&d.sentBytes)),
+			ClientSentMessagesPerRPC.M(atomic.LoadInt64(&d.sentCount)),
+			ClientReceivedMessagesPerRPC.M(atomic.LoadInt64(&d.recvCount)),
+			ClientReceivedBytesPerRPC.M(atomic.LoadInt64(&d.recvBytes)),
+			ClientRoundtripLatency.M(latencyMillis))
+	} else {
+		ctx, _ = tag.New(ctx, tag.Upsert(KeyServerStatus, st))
+		ocstats.Record(ctx,
+			ServerSentBytesPerRPC.M(atomic.LoadInt64(&d.sentBytes)),
+			ServerSentMessagesPerRPC.M(atomic.LoadInt64(&d.sentCount)),
+			ServerReceivedMessagesPerRPC.M(atomic.LoadInt64(&d.recvCount)),
+			ServerReceivedBytesPerRPC.M(atomic.LoadInt64(&d.recvBytes)),
+			ServerLatency.M(latencyMillis))
+	}
+}
+
+func statusCodeToString(s *status.Status) string {
+	// see https://github.com/grpc/grpc/blob/master/doc/statuscodes.md
+	switch c := s.Code(); c {
+	case codes.OK:
+		return "OK"
+	case codes.Canceled:
+		return "CANCELLED"
+	case codes.Unknown:
+		return "UNKNOWN"
+	case codes.InvalidArgument:
+		return "INVALID_ARGUMENT"
+	case codes.DeadlineExceeded:
+		return "DEADLINE_EXCEEDED"
+	case codes.NotFound:
+		return "NOT_FOUND"
+	case codes.AlreadyExists:
+		return "ALREADY_EXISTS"
+	case codes.PermissionDenied:
+		return "PERMISSION_DENIED"
+	case codes.ResourceExhausted:
+		return "RESOURCE_EXHAUSTED"
+	case codes.FailedPrecondition:
+		return "FAILED_PRECONDITION"
+	case codes.Aborted:
+		return "ABORTED"
+	case codes.OutOfRange:
+		return "OUT_OF_RANGE"
+	case codes.Unimplemented:
+		return "UNIMPLEMENTED"
+	case codes.Internal:
+		return "INTERNAL"
+	case codes.Unavailable:
+		return "UNAVAILABLE"
+	case codes.DataLoss:
+		return "DATA_LOSS"
+	case codes.Unauthenticated:
+		return "UNAUTHENTICATED"
+	default:
+		return "CODE_" + strconv.FormatInt(int64(c), 10)
+	}
+}
diff --git a/vendor/go.opencensus.io/plugin/ocgrpc/trace_common.go b/vendor/go.opencensus.io/plugin/ocgrpc/trace_common.go
new file mode 100644
index 0000000..720f381
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ocgrpc/trace_common.go
@@ -0,0 +1,107 @@
+// Copyright 2017, OpenCensus 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 ocgrpc
+
+import (
+	"strings"
+
+	"google.golang.org/grpc/codes"
+
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/propagation"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+)
+
+const traceContextKey = "grpc-trace-bin"
+
+// TagRPC creates a new trace span for the client side of the RPC.
+//
+// It returns ctx with the new trace span added and a serialization of the
+// SpanContext added to the outgoing gRPC metadata.
+func (c *ClientHandler) traceTagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	name := strings.TrimPrefix(rti.FullMethodName, "/")
+	name = strings.Replace(name, "/", ".", -1)
+	ctx, span := trace.StartSpan(ctx, name,
+		trace.WithSampler(c.StartOptions.Sampler),
+		trace.WithSpanKind(trace.SpanKindClient)) // span is ended by traceHandleRPC
+	traceContextBinary := propagation.Binary(span.SpanContext())
+	return metadata.AppendToOutgoingContext(ctx, traceContextKey, string(traceContextBinary))
+}
+
+// TagRPC creates a new trace span for the server side of the RPC.
+//
+// It checks the incoming gRPC metadata in ctx for a SpanContext, and if
+// it finds one, uses that SpanContext as the parent context of the new span.
+//
+// It returns ctx, with the new trace span added.
+func (s *ServerHandler) traceTagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	md, _ := metadata.FromIncomingContext(ctx)
+	name := strings.TrimPrefix(rti.FullMethodName, "/")
+	name = strings.Replace(name, "/", ".", -1)
+	traceContext := md[traceContextKey]
+	var (
+		parent     trace.SpanContext
+		haveParent bool
+	)
+	if len(traceContext) > 0 {
+		// Metadata with keys ending in -bin are actually binary. They are base64
+		// encoded before being put on the wire, see:
+		// https://github.com/grpc/grpc-go/blob/08d6261/Documentation/grpc-metadata.md#storing-binary-data-in-metadata
+		traceContextBinary := []byte(traceContext[0])
+		parent, haveParent = propagation.FromBinary(traceContextBinary)
+		if haveParent && !s.IsPublicEndpoint {
+			ctx, _ := trace.StartSpanWithRemoteParent(ctx, name, parent,
+				trace.WithSpanKind(trace.SpanKindServer),
+				trace.WithSampler(s.StartOptions.Sampler),
+			)
+			return ctx
+		}
+	}
+	ctx, span := trace.StartSpan(ctx, name,
+		trace.WithSpanKind(trace.SpanKindServer),
+		trace.WithSampler(s.StartOptions.Sampler))
+	if haveParent {
+		span.AddLink(trace.Link{TraceID: parent.TraceID, SpanID: parent.SpanID, Type: trace.LinkTypeChild})
+	}
+	return ctx
+}
+
+func traceHandleRPC(ctx context.Context, rs stats.RPCStats) {
+	span := trace.FromContext(ctx)
+	// TODO: compressed and uncompressed sizes are not populated in every message.
+	switch rs := rs.(type) {
+	case *stats.Begin:
+		span.AddAttributes(
+			trace.BoolAttribute("Client", rs.Client),
+			trace.BoolAttribute("FailFast", rs.FailFast))
+	case *stats.InPayload:
+		span.AddMessageReceiveEvent(0 /* TODO: messageID */, int64(rs.Length), int64(rs.WireLength))
+	case *stats.OutPayload:
+		span.AddMessageSendEvent(0, int64(rs.Length), int64(rs.WireLength))
+	case *stats.End:
+		if rs.Error != nil {
+			s, ok := status.FromError(rs.Error)
+			if ok {
+				span.SetStatus(trace.Status{Code: int32(s.Code()), Message: s.Message()})
+			} else {
+				span.SetStatus(trace.Status{Code: int32(codes.Internal), Message: rs.Error.Error()})
+			}
+		}
+		span.End()
+	}
+}
diff --git a/vendor/go.opencensus.io/plugin/ochttp/client.go b/vendor/go.opencensus.io/plugin/ochttp/client.go
new file mode 100644
index 0000000..37f42b3
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ochttp/client.go
@@ -0,0 +1,84 @@
+// Copyright 2018, OpenCensus 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 ochttp
+
+import (
+	"net/http"
+
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/propagation"
+)
+
+// Transport is an http.RoundTripper that instruments all outgoing requests with
+// stats and tracing. The zero value is intended to be a useful default, but for
+// now it's recommended that you explicitly set Propagation.
+type Transport struct {
+	// Base may be set to wrap another http.RoundTripper that does the actual
+	// requests. By default http.DefaultTransport is used.
+	//
+	// If base HTTP roundtripper implements CancelRequest,
+	// the returned round tripper will be cancelable.
+	Base http.RoundTripper
+
+	// Propagation defines how traces are propagated. If unspecified, a default
+	// (currently B3 format) will be used.
+	Propagation propagation.HTTPFormat
+
+	// StartOptions are applied to the span started by this Transport around each
+	// request.
+	//
+	// StartOptions.SpanKind will always be set to trace.SpanKindClient
+	// for spans started by this transport.
+	StartOptions trace.StartOptions
+
+	// TODO: Implement tag propagation for HTTP.
+}
+
+// RoundTrip implements http.RoundTripper, delegating to Base and recording stats and traces for the request.
+func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
+	rt := t.base()
+	// TODO: remove excessive nesting of http.RoundTrippers here.
+	format := t.Propagation
+	if format == nil {
+		format = defaultFormat
+	}
+	rt = &traceTransport{
+		base:   rt,
+		format: format,
+		startOptions: trace.StartOptions{
+			Sampler:  t.StartOptions.Sampler,
+			SpanKind: trace.SpanKindClient,
+		},
+	}
+	rt = statsTransport{base: rt}
+	return rt.RoundTrip(req)
+}
+
+func (t *Transport) base() http.RoundTripper {
+	if t.Base != nil {
+		return t.Base
+	}
+	return http.DefaultTransport
+}
+
+// CancelRequest cancels an in-flight request by closing its connection.
+func (t *Transport) CancelRequest(req *http.Request) {
+	type canceler interface {
+		CancelRequest(*http.Request)
+	}
+	if cr, ok := t.base().(canceler); ok {
+		cr.CancelRequest(req)
+	}
+}
diff --git a/vendor/go.opencensus.io/plugin/ochttp/client_stats.go b/vendor/go.opencensus.io/plugin/ochttp/client_stats.go
new file mode 100644
index 0000000..9b286b9
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ochttp/client_stats.go
@@ -0,0 +1,125 @@
+// Copyright 2018, OpenCensus 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 ochttp
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"strconv"
+	"sync"
+	"time"
+
+	"go.opencensus.io/stats"
+	"go.opencensus.io/tag"
+)
+
+// statsTransport is an http.RoundTripper that collects stats for the outgoing requests.
+type statsTransport struct {
+	base http.RoundTripper
+}
+
+// RoundTrip implements http.RoundTripper, delegating to Base and recording stats for the request.
+func (t statsTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	ctx, _ := tag.New(req.Context(),
+		tag.Upsert(Host, req.URL.Host),
+		tag.Upsert(Path, req.URL.Path),
+		tag.Upsert(Method, req.Method))
+	req = req.WithContext(ctx)
+	track := &tracker{
+		start: time.Now(),
+		ctx:   ctx,
+	}
+	if req.Body == nil {
+		// TODO: Handle cases where ContentLength is not set.
+		track.reqSize = -1
+	} else if req.ContentLength > 0 {
+		track.reqSize = req.ContentLength
+	}
+	stats.Record(ctx, ClientRequestCount.M(1))
+
+	// Perform request.
+	resp, err := t.base.RoundTrip(req)
+
+	if err != nil {
+		track.statusCode = http.StatusInternalServerError
+		track.end()
+	} else {
+		track.statusCode = resp.StatusCode
+		if resp.Body == nil {
+			track.end()
+		} else {
+			track.body = resp.Body
+			resp.Body = track
+		}
+	}
+	return resp, err
+}
+
+// CancelRequest cancels an in-flight request by closing its connection.
+func (t statsTransport) CancelRequest(req *http.Request) {
+	type canceler interface {
+		CancelRequest(*http.Request)
+	}
+	if cr, ok := t.base.(canceler); ok {
+		cr.CancelRequest(req)
+	}
+}
+
+type tracker struct {
+	ctx        context.Context
+	respSize   int64
+	reqSize    int64
+	start      time.Time
+	body       io.ReadCloser
+	statusCode int
+	endOnce    sync.Once
+}
+
+var _ io.ReadCloser = (*tracker)(nil)
+
+func (t *tracker) end() {
+	t.endOnce.Do(func() {
+		m := []stats.Measurement{
+			ClientLatency.M(float64(time.Since(t.start)) / float64(time.Millisecond)),
+			ClientResponseBytes.M(t.respSize),
+		}
+		if t.reqSize >= 0 {
+			m = append(m, ClientRequestBytes.M(t.reqSize))
+		}
+		ctx, _ := tag.New(t.ctx, tag.Upsert(StatusCode, strconv.Itoa(t.statusCode)))
+		stats.Record(ctx, m...)
+	})
+}
+
+func (t *tracker) Read(b []byte) (int, error) {
+	n, err := t.body.Read(b)
+	switch err {
+	case nil:
+		t.respSize += int64(n)
+		return n, nil
+	case io.EOF:
+		t.end()
+	}
+	return n, err
+}
+
+func (t *tracker) Close() error {
+	// Invoking endSpan on Close will help catch the cases
+	// in which a read returned a non-nil error, we set the
+	// span status but didn't end the span.
+	t.end()
+	return t.body.Close()
+}
diff --git a/vendor/go.opencensus.io/plugin/ochttp/doc.go b/vendor/go.opencensus.io/plugin/ochttp/doc.go
new file mode 100644
index 0000000..10e626b
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ochttp/doc.go
@@ -0,0 +1,19 @@
+// Copyright 2018, OpenCensus 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 ochttp provides OpenCensus instrumentation for net/http package.
+//
+// For server instrumentation, see Handler. For client-side instrumentation,
+// see Transport.
+package ochttp // import "go.opencensus.io/plugin/ochttp"
diff --git a/vendor/go.opencensus.io/plugin/ochttp/propagation/b3/b3.go b/vendor/go.opencensus.io/plugin/ochttp/propagation/b3/b3.go
new file mode 100644
index 0000000..f777772
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ochttp/propagation/b3/b3.go
@@ -0,0 +1,123 @@
+// Copyright 2018, OpenCensus 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 b3 contains a propagation.HTTPFormat implementation
+// for B3 propagation. See https://github.com/openzipkin/b3-propagation
+// for more details.
+package b3 // import "go.opencensus.io/plugin/ochttp/propagation/b3"
+
+import (
+	"encoding/hex"
+	"net/http"
+
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/propagation"
+)
+
+// B3 headers that OpenCensus understands.
+const (
+	TraceIDHeader = "X-B3-TraceId"
+	SpanIDHeader  = "X-B3-SpanId"
+	SampledHeader = "X-B3-Sampled"
+)
+
+// HTTPFormat implements propagation.HTTPFormat to propagate
+// traces in HTTP headers in B3 propagation format.
+// HTTPFormat skips the X-B3-ParentId and X-B3-Flags headers
+// because there are additional fields not represented in the
+// OpenCensus span context. Spans created from the incoming
+// header will be the direct children of the client-side span.
+// Similarly, reciever of the outgoing spans should use client-side
+// span created by OpenCensus as the parent.
+type HTTPFormat struct{}
+
+var _ propagation.HTTPFormat = (*HTTPFormat)(nil)
+
+// SpanContextFromRequest extracts a B3 span context from incoming requests.
+func (f *HTTPFormat) SpanContextFromRequest(req *http.Request) (sc trace.SpanContext, ok bool) {
+	tid, ok := ParseTraceID(req.Header.Get(TraceIDHeader))
+	if !ok {
+		return trace.SpanContext{}, false
+	}
+	sid, ok := ParseSpanID(req.Header.Get(SpanIDHeader))
+	if !ok {
+		return trace.SpanContext{}, false
+	}
+	sampled, _ := ParseSampled(req.Header.Get(SampledHeader))
+	return trace.SpanContext{
+		TraceID:      tid,
+		SpanID:       sid,
+		TraceOptions: sampled,
+	}, true
+}
+
+// ParseTraceID parses the value of the X-B3-TraceId header.
+func ParseTraceID(tid string) (trace.TraceID, bool) {
+	if tid == "" {
+		return trace.TraceID{}, false
+	}
+	b, err := hex.DecodeString(tid)
+	if err != nil {
+		return trace.TraceID{}, false
+	}
+	var traceID trace.TraceID
+	if len(b) <= 8 {
+		// The lower 64-bits.
+		start := 8 + (8 - len(b))
+		copy(traceID[start:], b)
+	} else {
+		start := 16 - len(b)
+		copy(traceID[start:], b)
+	}
+
+	return traceID, true
+}
+
+// ParseSpanID parses the value of the X-B3-SpanId or X-B3-ParentSpanId headers.
+func ParseSpanID(sid string) (spanID trace.SpanID, ok bool) {
+	if sid == "" {
+		return trace.SpanID{}, false
+	}
+	b, err := hex.DecodeString(sid)
+	if err != nil {
+		return trace.SpanID{}, false
+	}
+	start := 8 - len(b)
+	copy(spanID[start:], b)
+	return spanID, true
+}
+
+// ParseSampled parses the value of the X-B3-Sampled header.
+func ParseSampled(sampled string) (trace.TraceOptions, bool) {
+	switch sampled {
+	case "true", "1":
+		return trace.TraceOptions(1), true
+	default:
+		return trace.TraceOptions(0), false
+	}
+}
+
+// SpanContextToRequest modifies the given request to include B3 headers.
+func (f *HTTPFormat) SpanContextToRequest(sc trace.SpanContext, req *http.Request) {
+	req.Header.Set(TraceIDHeader, hex.EncodeToString(sc.TraceID[:]))
+	req.Header.Set(SpanIDHeader, hex.EncodeToString(sc.SpanID[:]))
+
+	var sampled string
+	if sc.IsSampled() {
+		sampled = "1"
+	} else {
+		sampled = "0"
+	}
+	req.Header.Set(SampledHeader, sampled)
+}
diff --git a/vendor/go.opencensus.io/plugin/ochttp/server.go b/vendor/go.opencensus.io/plugin/ochttp/server.go
new file mode 100644
index 0000000..4b3c855
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ochttp/server.go
@@ -0,0 +1,217 @@
+// Copyright 2018, OpenCensus 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 ochttp
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"net"
+	"net/http"
+	"strconv"
+	"sync"
+	"time"
+
+	"go.opencensus.io/stats"
+	"go.opencensus.io/tag"
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/propagation"
+)
+
+// Handler is a http.Handler that is aware of the incoming request's span.
+//
+// The extracted span can be accessed from the incoming request's
+// context.
+//
+//    span := trace.FromContext(r.Context())
+//
+// The server span will be automatically ended at the end of ServeHTTP.
+//
+// Incoming propagation mechanism is determined by the given HTTP propagators.
+type Handler struct {
+	// Propagation defines how traces are propagated. If unspecified,
+	// B3 propagation will be used.
+	Propagation propagation.HTTPFormat
+
+	// Handler is the handler used to handle the incoming request.
+	Handler http.Handler
+
+	// StartOptions are applied to the span started by this Handler around each
+	// request.
+	//
+	// StartOptions.SpanKind will always be set to trace.SpanKindServer
+	// for spans started by this transport.
+	StartOptions trace.StartOptions
+
+	// IsPublicEndpoint should be set to true for publicly accessible HTTP(S)
+	// servers. If true, any trace metadata set on the incoming request will
+	// be added as a linked trace instead of being added as a parent of the
+	// current trace.
+	IsPublicEndpoint bool
+}
+
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	var traceEnd, statsEnd func()
+	r, traceEnd = h.startTrace(w, r)
+	defer traceEnd()
+	w, statsEnd = h.startStats(w, r)
+	defer statsEnd()
+	handler := h.Handler
+	if handler == nil {
+		handler = http.DefaultServeMux
+	}
+	handler.ServeHTTP(w, r)
+}
+
+func (h *Handler) startTrace(w http.ResponseWriter, r *http.Request) (*http.Request, func()) {
+	name := spanNameFromURL(r.URL)
+	ctx := r.Context()
+	var span *trace.Span
+	sc, ok := h.extractSpanContext(r)
+	if ok && !h.IsPublicEndpoint {
+		ctx, span = trace.StartSpanWithRemoteParent(ctx, name, sc,
+			trace.WithSampler(h.StartOptions.Sampler),
+			trace.WithSpanKind(trace.SpanKindServer))
+	} else {
+		ctx, span = trace.StartSpan(ctx, name,
+			trace.WithSampler(h.StartOptions.Sampler),
+			trace.WithSpanKind(trace.SpanKindServer),
+		)
+		if ok {
+			span.AddLink(trace.Link{
+				TraceID:    sc.TraceID,
+				SpanID:     sc.SpanID,
+				Type:       trace.LinkTypeChild,
+				Attributes: nil,
+			})
+		}
+	}
+	span.AddAttributes(requestAttrs(r)...)
+	return r.WithContext(ctx), span.End
+}
+
+func (h *Handler) extractSpanContext(r *http.Request) (trace.SpanContext, bool) {
+	if h.Propagation == nil {
+		return defaultFormat.SpanContextFromRequest(r)
+	}
+	return h.Propagation.SpanContextFromRequest(r)
+}
+
+func (h *Handler) startStats(w http.ResponseWriter, r *http.Request) (http.ResponseWriter, func()) {
+	ctx, _ := tag.New(r.Context(),
+		tag.Upsert(Host, r.URL.Host),
+		tag.Upsert(Path, r.URL.Path),
+		tag.Upsert(Method, r.Method))
+	track := &trackingResponseWriter{
+		start:  time.Now(),
+		ctx:    ctx,
+		writer: w,
+	}
+	if r.Body == nil {
+		// TODO: Handle cases where ContentLength is not set.
+		track.reqSize = -1
+	} else if r.ContentLength > 0 {
+		track.reqSize = r.ContentLength
+	}
+	stats.Record(ctx, ServerRequestCount.M(1))
+	return track, track.end
+}
+
+type trackingResponseWriter struct {
+	ctx        context.Context
+	reqSize    int64
+	respSize   int64
+	start      time.Time
+	statusCode int
+	statusLine string
+	endOnce    sync.Once
+	writer     http.ResponseWriter
+}
+
+// Compile time assertions for widely used net/http interfaces
+var _ http.CloseNotifier = (*trackingResponseWriter)(nil)
+var _ http.Flusher = (*trackingResponseWriter)(nil)
+var _ http.Hijacker = (*trackingResponseWriter)(nil)
+var _ http.Pusher = (*trackingResponseWriter)(nil)
+var _ http.ResponseWriter = (*trackingResponseWriter)(nil)
+
+var errHijackerUnimplemented = errors.New("ResponseWriter does not implement http.Hijacker")
+
+func (t *trackingResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	hj, ok := t.writer.(http.Hijacker)
+	if !ok {
+		return nil, nil, errHijackerUnimplemented
+	}
+	return hj.Hijack()
+}
+
+func (t *trackingResponseWriter) CloseNotify() <-chan bool {
+	cn, ok := t.writer.(http.CloseNotifier)
+	if !ok {
+		return nil
+	}
+	return cn.CloseNotify()
+}
+
+func (t *trackingResponseWriter) Push(target string, opts *http.PushOptions) error {
+	pusher, ok := t.writer.(http.Pusher)
+	if !ok {
+		return http.ErrNotSupported
+	}
+	return pusher.Push(target, opts)
+}
+
+func (t *trackingResponseWriter) end() {
+	t.endOnce.Do(func() {
+		if t.statusCode == 0 {
+			t.statusCode = 200
+		}
+
+		span := trace.FromContext(t.ctx)
+		span.SetStatus(TraceStatus(t.statusCode, t.statusLine))
+
+		m := []stats.Measurement{
+			ServerLatency.M(float64(time.Since(t.start)) / float64(time.Millisecond)),
+			ServerResponseBytes.M(t.respSize),
+		}
+		if t.reqSize >= 0 {
+			m = append(m, ServerRequestBytes.M(t.reqSize))
+		}
+		ctx, _ := tag.New(t.ctx, tag.Upsert(StatusCode, strconv.Itoa(t.statusCode)))
+		stats.Record(ctx, m...)
+	})
+}
+
+func (t *trackingResponseWriter) Header() http.Header {
+	return t.writer.Header()
+}
+
+func (t *trackingResponseWriter) Write(data []byte) (int, error) {
+	n, err := t.writer.Write(data)
+	t.respSize += int64(n)
+	return n, err
+}
+
+func (t *trackingResponseWriter) WriteHeader(statusCode int) {
+	t.writer.WriteHeader(statusCode)
+	t.statusCode = statusCode
+	t.statusLine = http.StatusText(t.statusCode)
+}
+
+func (t *trackingResponseWriter) Flush() {
+	if flusher, ok := t.writer.(http.Flusher); ok {
+		flusher.Flush()
+	}
+}
diff --git a/vendor/go.opencensus.io/plugin/ochttp/stats.go b/vendor/go.opencensus.io/plugin/ochttp/stats.go
new file mode 100644
index 0000000..2bd11f6
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ochttp/stats.go
@@ -0,0 +1,173 @@
+// Copyright 2018, OpenCensus 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 ochttp
+
+import (
+	"go.opencensus.io/stats"
+	"go.opencensus.io/stats/view"
+	"go.opencensus.io/tag"
+)
+
+// The following client HTTP measures are supported for use in custom views.
+var (
+	ClientRequestCount  = stats.Int64("opencensus.io/http/client/request_count", "Number of HTTP requests started", stats.UnitDimensionless)
+	ClientRequestBytes  = stats.Int64("opencensus.io/http/client/request_bytes", "HTTP request body size if set as ContentLength (uncompressed)", stats.UnitBytes)
+	ClientResponseBytes = stats.Int64("opencensus.io/http/client/response_bytes", "HTTP response body size (uncompressed)", stats.UnitBytes)
+	ClientLatency       = stats.Float64("opencensus.io/http/client/latency", "End-to-end latency", stats.UnitMilliseconds)
+)
+
+// The following server HTTP measures are supported for use in custom views:
+var (
+	ServerRequestCount  = stats.Int64("opencensus.io/http/server/request_count", "Number of HTTP requests started", stats.UnitDimensionless)
+	ServerRequestBytes  = stats.Int64("opencensus.io/http/server/request_bytes", "HTTP request body size if set as ContentLength (uncompressed)", stats.UnitBytes)
+	ServerResponseBytes = stats.Int64("opencensus.io/http/server/response_bytes", "HTTP response body size (uncompressed)", stats.UnitBytes)
+	ServerLatency       = stats.Float64("opencensus.io/http/server/latency", "End-to-end latency", stats.UnitMilliseconds)
+)
+
+// The following tags are applied to stats recorded by this package. Host, Path
+// and Method are applied to all measures. StatusCode is not applied to
+// ClientRequestCount or ServerRequestCount, since it is recorded before the status is known.
+var (
+	// Host is the value of the HTTP Host header.
+	Host, _ = tag.NewKey("http.host")
+
+	// StatusCode is the numeric HTTP response status code,
+	// or "error" if a transport error occurred and no status code was read.
+	StatusCode, _ = tag.NewKey("http.status")
+
+	// Path is the URL path (not including query string) in the request.
+	Path, _ = tag.NewKey("http.path")
+
+	// Method is the HTTP method of the request, capitalized (GET, POST, etc.).
+	Method, _ = tag.NewKey("http.method")
+)
+
+// Default distributions used by views in this package.
+var (
+	DefaultSizeDistribution    = view.Distribution(0, 1024, 2048, 4096, 16384, 65536, 262144, 1048576, 4194304, 16777216, 67108864, 268435456, 1073741824, 4294967296)
+	DefaultLatencyDistribution = view.Distribution(0, 1, 2, 3, 4, 5, 6, 8, 10, 13, 16, 20, 25, 30, 40, 50, 65, 80, 100, 130, 160, 200, 250, 300, 400, 500, 650, 800, 1000, 2000, 5000, 10000, 20000, 50000, 100000)
+)
+
+// Package ochttp provides some convenience views.
+// You need to subscribe to the views for data to actually be collected.
+var (
+	ClientRequestCountView = &view.View{
+		Name:        "opencensus.io/http/client/request_count",
+		Description: "Count of HTTP requests started",
+		Measure:     ClientRequestCount,
+		Aggregation: view.Count(),
+	}
+
+	ClientRequestBytesView = &view.View{
+		Name:        "opencensus.io/http/client/request_bytes",
+		Description: "Size distribution of HTTP request body",
+		Measure:     ClientRequestBytes,
+		Aggregation: DefaultSizeDistribution,
+	}
+
+	ClientResponseBytesView = &view.View{
+		Name:        "opencensus.io/http/client/response_bytes",
+		Description: "Size distribution of HTTP response body",
+		Measure:     ClientResponseBytes,
+		Aggregation: DefaultSizeDistribution,
+	}
+
+	ClientLatencyView = &view.View{
+		Name:        "opencensus.io/http/client/latency",
+		Description: "Latency distribution of HTTP requests",
+		Measure:     ClientLatency,
+		Aggregation: DefaultLatencyDistribution,
+	}
+
+	ClientRequestCountByMethod = &view.View{
+		Name:        "opencensus.io/http/client/request_count_by_method",
+		Description: "Client request count by HTTP method",
+		TagKeys:     []tag.Key{Method},
+		Measure:     ClientRequestCount,
+		Aggregation: view.Count(),
+	}
+
+	ClientResponseCountByStatusCode = &view.View{
+		Name:        "opencensus.io/http/client/response_count_by_status_code",
+		Description: "Client response count by status code",
+		TagKeys:     []tag.Key{StatusCode},
+		Measure:     ClientLatency,
+		Aggregation: view.Count(),
+	}
+
+	ServerRequestCountView = &view.View{
+		Name:        "opencensus.io/http/server/request_count",
+		Description: "Count of HTTP requests started",
+		Measure:     ServerRequestCount,
+		Aggregation: view.Count(),
+	}
+
+	ServerRequestBytesView = &view.View{
+		Name:        "opencensus.io/http/server/request_bytes",
+		Description: "Size distribution of HTTP request body",
+		Measure:     ServerRequestBytes,
+		Aggregation: DefaultSizeDistribution,
+	}
+
+	ServerResponseBytesView = &view.View{
+		Name:        "opencensus.io/http/server/response_bytes",
+		Description: "Size distribution of HTTP response body",
+		Measure:     ServerResponseBytes,
+		Aggregation: DefaultSizeDistribution,
+	}
+
+	ServerLatencyView = &view.View{
+		Name:        "opencensus.io/http/server/latency",
+		Description: "Latency distribution of HTTP requests",
+		Measure:     ServerLatency,
+		Aggregation: DefaultLatencyDistribution,
+	}
+
+	ServerRequestCountByMethod = &view.View{
+		Name:        "opencensus.io/http/server/request_count_by_method",
+		Description: "Server request count by HTTP method",
+		TagKeys:     []tag.Key{Method},
+		Measure:     ServerRequestCount,
+		Aggregation: view.Count(),
+	}
+
+	ServerResponseCountByStatusCode = &view.View{
+		Name:        "opencensus.io/http/server/response_count_by_status_code",
+		Description: "Server response count by status code",
+		TagKeys:     []tag.Key{StatusCode},
+		Measure:     ServerLatency,
+		Aggregation: view.Count(),
+	}
+)
+
+// DefaultClientViews are the default client views provided by this package.
+var DefaultClientViews = []*view.View{
+	ClientRequestCountView,
+	ClientRequestBytesView,
+	ClientResponseBytesView,
+	ClientLatencyView,
+	ClientRequestCountByMethod,
+	ClientResponseCountByStatusCode,
+}
+
+// DefaultServerViews are the default server views provided by this package.
+var DefaultServerViews = []*view.View{
+	ServerRequestCountView,
+	ServerRequestBytesView,
+	ServerResponseBytesView,
+	ServerLatencyView,
+	ServerRequestCountByMethod,
+	ServerResponseCountByStatusCode,
+}
diff --git a/vendor/go.opencensus.io/plugin/ochttp/trace.go b/vendor/go.opencensus.io/plugin/ochttp/trace.go
new file mode 100644
index 0000000..79bbfd1
--- /dev/null
+++ b/vendor/go.opencensus.io/plugin/ochttp/trace.go
@@ -0,0 +1,199 @@
+// Copyright 2018, OpenCensus 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 ochttp
+
+import (
+	"io"
+	"net/http"
+	"net/url"
+
+	"go.opencensus.io/plugin/ochttp/propagation/b3"
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/propagation"
+)
+
+// TODO(jbd): Add godoc examples.
+
+var defaultFormat propagation.HTTPFormat = &b3.HTTPFormat{}
+
+// Attributes recorded on the span for the requests.
+// Only trace exporters will need them.
+const (
+	HostAttribute       = "http.host"
+	MethodAttribute     = "http.method"
+	PathAttribute       = "http.path"
+	UserAgentAttribute  = "http.user_agent"
+	StatusCodeAttribute = "http.status_code"
+)
+
+type traceTransport struct {
+	base         http.RoundTripper
+	startOptions trace.StartOptions
+	format       propagation.HTTPFormat
+}
+
+// TODO(jbd): Add message events for request and response size.
+
+// RoundTrip creates a trace.Span and inserts it into the outgoing request's headers.
+// The created span can follow a parent span, if a parent is presented in
+// the request's context.
+func (t *traceTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	name := spanNameFromURL(req.URL)
+	// TODO(jbd): Discuss whether we want to prefix
+	// outgoing requests with Sent.
+	_, span := trace.StartSpan(req.Context(), name,
+		trace.WithSampler(t.startOptions.Sampler),
+		trace.WithSpanKind(trace.SpanKindClient))
+
+	req = req.WithContext(trace.WithSpan(req.Context(), span))
+	if t.format != nil {
+		t.format.SpanContextToRequest(span.SpanContext(), req)
+	}
+
+	span.AddAttributes(requestAttrs(req)...)
+	resp, err := t.base.RoundTrip(req)
+	if err != nil {
+		span.SetStatus(trace.Status{Code: trace.StatusCodeUnknown, Message: err.Error()})
+		span.End()
+		return resp, err
+	}
+
+	span.AddAttributes(responseAttrs(resp)...)
+	span.SetStatus(TraceStatus(resp.StatusCode, resp.Status))
+
+	// span.End() will be invoked after
+	// a read from resp.Body returns io.EOF or when
+	// resp.Body.Close() is invoked.
+	resp.Body = &bodyTracker{rc: resp.Body, span: span}
+	return resp, err
+}
+
+// bodyTracker wraps a response.Body and invokes
+// trace.EndSpan on encountering io.EOF on reading
+// the body of the original response.
+type bodyTracker struct {
+	rc   io.ReadCloser
+	span *trace.Span
+}
+
+var _ io.ReadCloser = (*bodyTracker)(nil)
+
+func (bt *bodyTracker) Read(b []byte) (int, error) {
+	n, err := bt.rc.Read(b)
+
+	switch err {
+	case nil:
+		return n, nil
+	case io.EOF:
+		bt.span.End()
+	default:
+		// For all other errors, set the span status
+		bt.span.SetStatus(trace.Status{
+			// Code 2 is the error code for Internal server error.
+			Code:    2,
+			Message: err.Error(),
+		})
+	}
+	return n, err
+}
+
+func (bt *bodyTracker) Close() error {
+	// Invoking endSpan on Close will help catch the cases
+	// in which a read returned a non-nil error, we set the
+	// span status but didn't end the span.
+	bt.span.End()
+	return bt.rc.Close()
+}
+
+// CancelRequest cancels an in-flight request by closing its connection.
+func (t *traceTransport) CancelRequest(req *http.Request) {
+	type canceler interface {
+		CancelRequest(*http.Request)
+	}
+	if cr, ok := t.base.(canceler); ok {
+		cr.CancelRequest(req)
+	}
+}
+
+func spanNameFromURL(u *url.URL) string {
+	return u.Path
+}
+
+func requestAttrs(r *http.Request) []trace.Attribute {
+	return []trace.Attribute{
+		trace.StringAttribute(PathAttribute, r.URL.Path),
+		trace.StringAttribute(HostAttribute, r.URL.Host),
+		trace.StringAttribute(MethodAttribute, r.Method),
+		trace.StringAttribute(UserAgentAttribute, r.UserAgent()),
+	}
+}
+
+func responseAttrs(resp *http.Response) []trace.Attribute {
+	return []trace.Attribute{
+		trace.Int64Attribute(StatusCodeAttribute, int64(resp.StatusCode)),
+	}
+}
+
+// TraceStatus converts the HTTP status code to a trace.Status that
+// represents the outcome as closely as possible.
+func TraceStatus(httpStatusCode int, statusLine string) trace.Status {
+	var code int32
+	if httpStatusCode < 200 || httpStatusCode >= 400 {
+		code = trace.StatusCodeUnknown
+	}
+	switch httpStatusCode {
+	case 499:
+		code = trace.StatusCodeCancelled
+	case http.StatusBadRequest:
+		code = trace.StatusCodeInvalidArgument
+	case http.StatusGatewayTimeout:
+		code = trace.StatusCodeDeadlineExceeded
+	case http.StatusNotFound:
+		code = trace.StatusCodeNotFound
+	case http.StatusForbidden:
+		code = trace.StatusCodePermissionDenied
+	case http.StatusUnauthorized: // 401 is actually unauthenticated.
+		code = trace.StatusCodeUnauthenticated
+	case http.StatusTooManyRequests:
+		code = trace.StatusCodeResourceExhausted
+	case http.StatusNotImplemented:
+		code = trace.StatusCodeUnimplemented
+	case http.StatusServiceUnavailable:
+		code = trace.StatusCodeUnavailable
+	case http.StatusOK:
+		code = trace.StatusCodeOK
+	}
+	return trace.Status{Code: code, Message: codeToStr[code]}
+}
+
+var codeToStr = map[int32]string{
+	trace.StatusCodeOK:                 `"OK"`,
+	trace.StatusCodeCancelled:          `"CANCELLED"`,
+	trace.StatusCodeUnknown:            `"UNKNOWN"`,
+	trace.StatusCodeInvalidArgument:    `"INVALID_ARGUMENT"`,
+	trace.StatusCodeDeadlineExceeded:   `"DEADLINE_EXCEEDED"`,
+	trace.StatusCodeNotFound:           `"NOT_FOUND"`,
+	trace.StatusCodeAlreadyExists:      `"ALREADY_EXISTS"`,
+	trace.StatusCodePermissionDenied:   `"PERMISSION_DENIED"`,
+	trace.StatusCodeResourceExhausted:  `"RESOURCE_EXHAUSTED"`,
+	trace.StatusCodeFailedPrecondition: `"FAILED_PRECONDITION"`,
+	trace.StatusCodeAborted:            `"ABORTED"`,
+	trace.StatusCodeOutOfRange:         `"OUT_OF_RANGE"`,
+	trace.StatusCodeUnimplemented:      `"UNIMPLEMENTED"`,
+	trace.StatusCodeInternal:           `"INTERNAL"`,
+	trace.StatusCodeUnavailable:        `"UNAVAILABLE"`,
+	trace.StatusCodeDataLoss:           `"DATA_LOSS"`,
+	trace.StatusCodeUnauthenticated:    `"UNAUTHENTICATED"`,
+}