diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/.gitignore b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/.gitignore
new file mode 100644
index 0000000..826caa3
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/.gitignore
@@ -0,0 +1,204 @@
+# Created by .ignore support plugin (hsz.mobi)
+### Go template
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test
+*.prof
+### Windows template
+# Windows image file caches
+Thumbs.db
+ehthumbs.db
+
+# Folder config file
+Desktop.ini
+
+# Recycle Bin used on file shares
+$RECYCLE.BIN/
+
+# Windows Installer files
+*.cab
+*.msi
+*.msm
+*.msp
+
+# Windows shortcuts
+*.lnk
+### Kate template
+# Swap Files #
+.*.kate-swp
+.swp.*
+### SublimeText template
+# cache files for sublime text
+*.tmlanguage.cache
+*.tmPreferences.cache
+*.stTheme.cache
+
+# workspace files are user-specific
+*.sublime-workspace
+
+# project files should be checked into the repository, unless a significant
+# proportion of contributors will probably not be using SublimeText
+# *.sublime-project
+
+# sftp configuration file
+sftp-config.json
+### Linux template
+*~
+
+# temporary files which can be created if a process still has a handle open of a deleted file
+.fuse_hidden*
+
+# KDE directory preferences
+.directory
+
+# Linux trash folder which might appear on any partition or disk
+.Trash-*
+### JetBrains template
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio and Webstorm
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff:
+.idea
+.idea/tasks.xml
+.idea/dictionaries
+.idea/vcs.xml
+.idea/jsLibraryMappings.xml
+
+# Sensitive or high-churn files:
+.idea/dataSources.ids
+.idea/dataSources.xml
+.idea/dataSources.local.xml
+.idea/sqlDataSources.xml
+.idea/dynamic.xml
+.idea/uiDesigner.xml
+
+# Gradle:
+.idea/gradle.xml
+.idea/libraries
+
+# Mongo Explorer plugin:
+.idea/mongoSettings.xml
+
+## File-based project format:
+*.iws
+
+## Plugin-specific files:
+
+# IntelliJ
+/out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+### Xcode template
+# Xcode
+#
+# gitignore contributors: remember to update Global/Xcode.gitignore, Objective-C.gitignore & Swift.gitignore
+
+## Build generated
+build/
+DerivedData/
+
+## Various settings
+*.pbxuser
+!default.pbxuser
+*.mode1v3
+!default.mode1v3
+*.mode2v3
+!default.mode2v3
+*.perspectivev3
+!default.perspectivev3
+xcuserdata/
+
+## Other
+*.moved-aside
+*.xccheckout
+*.xcscmblueprint
+### Eclipse template
+
+.metadata
+bin/
+tmp/
+*.tmp
+*.bak
+*.swp
+*~.nib
+local.properties
+.settings/
+.loadpath
+.recommenders
+
+# Eclipse Core
+.project
+
+# External tool builders
+.externalToolBuilders/
+
+# Locally stored "Eclipse launch configurations"
+*.launch
+
+# PyDev specific (Python IDE for Eclipse)
+*.pydevproject
+
+# CDT-specific (C/C++ Development Tooling)
+.cproject
+
+# JDT-specific (Eclipse Java Development Tools)
+.classpath
+
+# Java annotation processor (APT)
+.factorypath
+
+# PDT-specific (PHP Development Tools)
+.buildpath
+
+# sbteclipse plugin
+.target
+
+# Tern plugin
+.tern-project
+
+# TeXlipse plugin
+.texlipse
+
+# STS (Spring Tool Suite)
+.springBeans
+
+# Code Recommenders
+.recommenders/
+
+
+coverage.txt
+
+#vendor
+vendor/
+
+.envrc
\ No newline at end of file
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/CONTRIBUTING.md b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/CONTRIBUTING.md
new file mode 100644
index 0000000..dd52ab8
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/CONTRIBUTING.md
@@ -0,0 +1,20 @@
+# Contributing
+
+We would love to have people submit pull requests and help make `grpc-ecosystem/go-grpc-middleware` even better 👍.
+
+Fork, then clone the repo:
+
+```bash
+git clone git@github.com:your-username/go-grpc-middleware.git
+```    
+
+Before checking in please run the following:
+
+```bash
+make all
+```
+
+This will `vet`, `fmt`, regenerate documentation and run all tests.
+
+
+Push to your fork and open a pull request.
\ No newline at end of file
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/LICENSE b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/LICENSE
new file mode 100644
index 0000000..b2b0650
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/LICENSE
@@ -0,0 +1,201 @@
+                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
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+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
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+      negligent acts) or agreed to in writing, shall any Contributor be
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+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
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+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
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+
+   Copyright [yyyy] [name of copyright owner]
+
+   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.
\ No newline at end of file
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/README.md b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/README.md
new file mode 100644
index 0000000..a12b409
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/README.md
@@ -0,0 +1,93 @@
+# Go gRPC Middleware
+
+[![Travis Build](https://travis-ci.org/grpc-ecosystem/go-grpc-middleware.svg?branch=master)](https://travis-ci.org/grpc-ecosystem/go-grpc-middleware)
+[![Go Report Card](https://goreportcard.com/badge/github.com/grpc-ecosystem/go-grpc-middleware)](https://goreportcard.com/report/github.com/grpc-ecosystem/go-grpc-middleware)
+[![GoDoc](http://img.shields.io/badge/GoDoc-Reference-blue.svg)](https://godoc.org/github.com/grpc-ecosystem/go-grpc-middleware)
+[![SourceGraph](https://sourcegraph.com/github.com/grpc-ecosystem/go-grpc-middleware/-/badge.svg)](https://sourcegraph.com/github.com/grpc-ecosystem/go-grpc-middleware/?badge)
+[![codecov](https://codecov.io/gh/grpc-ecosystem/go-grpc-middleware/branch/master/graph/badge.svg)](https://codecov.io/gh/grpc-ecosystem/go-grpc-middleware)
+[![Apache 2.0 License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](LICENSE)
+[![quality: production](https://img.shields.io/badge/quality-production-orange.svg)](#status)
+[![Slack](https://img.shields.io/badge/slack-%23grpc--middleware-brightgreen)](https://gophers.slack.com/archives/CNJL30P4P)
+
+[gRPC Go](https://github.com/grpc/grpc-go) Middleware: interceptors, helpers, utilities.
+
+## ⚠️  Status
+
+Version [v2](https://github.com/grpc-ecosystem/go-grpc-middleware/tree/v2) is about to be released, with migration guide, which will replace v1. Try v2 and give us feedback! 
+
+Version v1 is currently in deprecation mode, which means only critical and safety bug fixes will be merged.
+
+
+## Middleware
+
+[gRPC Go](https://github.com/grpc/grpc-go) recently acquired support for
+Interceptors, i.e. [middleware](https://medium.com/@matryer/writing-middleware-in-golang-and-how-go-makes-it-so-much-fun-4375c1246e81#.gv7tdlghs)
+that is executed either on the gRPC Server before the request is passed onto the user's application logic, or on the gRPC client around the user call. It is a perfect way to implement
+common patterns: auth, logging, message, validation, retries, or monitoring.
+
+These are generic building blocks that make it easy to build multiple microservices easily.
+The purpose of this repository is to act as a go-to point for such reusable functionality. It contains
+some of them itself, but also will link to useful external repos.
+
+`grpc_middleware` itself provides support for chaining interceptors, here's an example:
+
+```go
+import "github.com/grpc-ecosystem/go-grpc-middleware"
+
+myServer := grpc.NewServer(
+    grpc.StreamInterceptor(grpc_middleware.ChainStreamServer(
+        grpc_ctxtags.StreamServerInterceptor(),
+        grpc_opentracing.StreamServerInterceptor(),
+        grpc_prometheus.StreamServerInterceptor,
+        grpc_zap.StreamServerInterceptor(zapLogger),
+        grpc_auth.StreamServerInterceptor(myAuthFunction),
+        grpc_recovery.StreamServerInterceptor(),
+    )),
+    grpc.UnaryInterceptor(grpc_middleware.ChainUnaryServer(
+        grpc_ctxtags.UnaryServerInterceptor(),
+        grpc_opentracing.UnaryServerInterceptor(),
+        grpc_prometheus.UnaryServerInterceptor,
+        grpc_zap.UnaryServerInterceptor(zapLogger),
+        grpc_auth.UnaryServerInterceptor(myAuthFunction),
+        grpc_recovery.UnaryServerInterceptor(),
+    )),
+)
+```
+
+## Interceptors
+
+_Please send a PR to add new interceptors or middleware to this list_
+
+#### Auth
+
+- [`grpc_auth`](auth) - a customizable (via `AuthFunc`) piece of auth middleware
+
+#### Logging
+
+- [`grpc_ctxtags`](tags/) - a library that adds a `Tag` map to context, with data populated from request body
+- [`grpc_zap`](logging/zap/) - integration of [zap](https://github.com/uber-go/zap) logging library into gRPC handlers.
+- [`grpc_logrus`](logging/logrus/) - integration of [logrus](https://github.com/sirupsen/logrus) logging library into gRPC handlers.
+- [`grpc_kit`](logging/kit/) - integration of [go-kit/log](https://github.com/go-kit/log) logging library into gRPC handlers.
+- [`grpc_grpc_logsettable`](logging/settable/) - a wrapper around `grpclog.LoggerV2` that allows to replace loggers in runtime (thread-safe).
+
+#### Monitoring
+
+- [`grpc_prometheus`⚡](https://github.com/grpc-ecosystem/go-grpc-prometheus) - Prometheus client-side and server-side monitoring middleware
+- [`otgrpc`⚡](https://github.com/grpc-ecosystem/grpc-opentracing/tree/master/go/otgrpc) - [OpenTracing](http://opentracing.io/) client-side and server-side interceptors
+- [`grpc_opentracing`](tracing/opentracing) - [OpenTracing](http://opentracing.io/) client-side and server-side interceptors with support for streaming and handler-returned tags
+- [`otelgrpc`](https://github.com/open-telemetry/opentelemetry-go-contrib/tree/main/instrumentation/google.golang.org/grpc/otelgrpc) - [OpenTelemetry](https://opentelemetry.io/) client-side and server-side interceptors
+
+#### Client
+
+- [`grpc_retry`](retry/) - a generic gRPC response code retry mechanism, client-side middleware
+
+#### Server
+
+- [`grpc_validator`](validator/) - codegen inbound message validation from `.proto` options
+- [`grpc_recovery`](recovery/) - turn panics into gRPC errors
+- [`ratelimit`](ratelimit/) - grpc rate limiting by your own limiter
+
+
+## License
+
+`go-grpc-middleware` is released under the Apache 2.0 license. See the [LICENSE](LICENSE) file for details.
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/chain.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/chain.go
new file mode 100644
index 0000000..407d933
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/chain.go
@@ -0,0 +1,166 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+// gRPC Server Interceptor chaining middleware.
+
+package grpc_middleware
+
+import (
+	"context"
+
+	"google.golang.org/grpc"
+)
+
+// ChainUnaryServer creates a single interceptor out of a chain of many interceptors.
+//
+// Execution is done in left-to-right order, including passing of context.
+// For example ChainUnaryServer(one, two, three) will execute one before two before three, and three
+// will see context changes of one and two.
+//
+// While this can be useful in some scenarios, it is generally advisable to use google.golang.org/grpc.ChainUnaryInterceptor directly.
+func ChainUnaryServer(interceptors ...grpc.UnaryServerInterceptor) grpc.UnaryServerInterceptor {
+	n := len(interceptors)
+
+	// Dummy interceptor maintained for backward compatibility to avoid returning nil.
+	if n == 0 {
+		return func(ctx context.Context, req interface{}, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+			return handler(ctx, req)
+		}
+	}
+
+	// The degenerate case, just return the single wrapped interceptor directly.
+	if n == 1 {
+		return interceptors[0]
+	}
+
+	// Return a function which satisfies the interceptor interface, and which is
+	// a closure over the given list of interceptors to be chained.
+	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+		currHandler := handler
+		// Iterate backwards through all interceptors except the first (outermost).
+		// Wrap each one in a function which satisfies the handler interface, but
+		// is also a closure over the `info` and `handler` parameters. Then pass
+		// each pseudo-handler to the next outer interceptor as the handler to be called.
+		for i := n - 1; i > 0; i-- {
+			// Rebind to loop-local vars so they can be closed over.
+			innerHandler, i := currHandler, i
+			currHandler = func(currentCtx context.Context, currentReq interface{}) (interface{}, error) {
+				return interceptors[i](currentCtx, currentReq, info, innerHandler)
+			}
+		}
+		// Finally return the result of calling the outermost interceptor with the
+		// outermost pseudo-handler created above as its handler.
+		return interceptors[0](ctx, req, info, currHandler)
+	}
+}
+
+// ChainStreamServer creates a single interceptor out of a chain of many interceptors.
+//
+// Execution is done in left-to-right order, including passing of context.
+// For example ChainUnaryServer(one, two, three) will execute one before two before three.
+// If you want to pass context between interceptors, use WrapServerStream.
+//
+// While this can be useful in some scenarios, it is generally advisable to use google.golang.org/grpc.ChainStreamInterceptor directly.
+func ChainStreamServer(interceptors ...grpc.StreamServerInterceptor) grpc.StreamServerInterceptor {
+	n := len(interceptors)
+
+	// Dummy interceptor maintained for backward compatibility to avoid returning nil.
+	if n == 0 {
+		return func(srv interface{}, stream grpc.ServerStream, _ *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+			return handler(srv, stream)
+		}
+	}
+
+	if n == 1 {
+		return interceptors[0]
+	}
+
+	return func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+		currHandler := handler
+		for i := n - 1; i > 0; i-- {
+			innerHandler, i := currHandler, i
+			currHandler = func(currentSrv interface{}, currentStream grpc.ServerStream) error {
+				return interceptors[i](currentSrv, currentStream, info, innerHandler)
+			}
+		}
+		return interceptors[0](srv, stream, info, currHandler)
+	}
+}
+
+// ChainUnaryClient creates a single interceptor out of a chain of many interceptors.
+//
+// Execution is done in left-to-right order, including passing of context.
+// For example ChainUnaryClient(one, two, three) will execute one before two before three.
+func ChainUnaryClient(interceptors ...grpc.UnaryClientInterceptor) grpc.UnaryClientInterceptor {
+	n := len(interceptors)
+
+	// Dummy interceptor maintained for backward compatibility to avoid returning nil.
+	if n == 0 {
+		return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+			return invoker(ctx, method, req, reply, cc, opts...)
+		}
+	}
+
+	if n == 1 {
+		return interceptors[0]
+	}
+
+	return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+		currInvoker := invoker
+		for i := n - 1; i > 0; i-- {
+			innerInvoker, i := currInvoker, i
+			currInvoker = func(currentCtx context.Context, currentMethod string, currentReq, currentRepl interface{}, currentConn *grpc.ClientConn, currentOpts ...grpc.CallOption) error {
+				return interceptors[i](currentCtx, currentMethod, currentReq, currentRepl, currentConn, innerInvoker, currentOpts...)
+			}
+		}
+		return interceptors[0](ctx, method, req, reply, cc, currInvoker, opts...)
+	}
+}
+
+// ChainStreamClient creates a single interceptor out of a chain of many interceptors.
+//
+// Execution is done in left-to-right order, including passing of context.
+// For example ChainStreamClient(one, two, three) will execute one before two before three.
+func ChainStreamClient(interceptors ...grpc.StreamClientInterceptor) grpc.StreamClientInterceptor {
+	n := len(interceptors)
+
+	// Dummy interceptor maintained for backward compatibility to avoid returning nil.
+	if n == 0 {
+		return func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
+			return streamer(ctx, desc, cc, method, opts...)
+		}
+	}
+
+	if n == 1 {
+		return interceptors[0]
+	}
+
+	return func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
+		currStreamer := streamer
+		for i := n - 1; i > 0; i-- {
+			innerStreamer, i := currStreamer, i
+			currStreamer = func(currentCtx context.Context, currentDesc *grpc.StreamDesc, currentConn *grpc.ClientConn, currentMethod string, currentOpts ...grpc.CallOption) (grpc.ClientStream, error) {
+				return interceptors[i](currentCtx, currentDesc, currentConn, currentMethod, innerStreamer, currentOpts...)
+			}
+		}
+		return interceptors[0](ctx, desc, cc, method, currStreamer, opts...)
+	}
+}
+
+// Chain creates a single interceptor out of a chain of many interceptors.
+//
+// WithUnaryServerChain is a grpc.Server config option that accepts multiple unary interceptors.
+// Basically syntactic sugar.
+//
+// Deprecated: use google.golang.org/grpc.ChainUnaryInterceptor instead.
+func WithUnaryServerChain(interceptors ...grpc.UnaryServerInterceptor) grpc.ServerOption {
+	return grpc.ChainUnaryInterceptor(interceptors...)
+}
+
+// WithStreamServerChain is a grpc.Server config option that accepts multiple stream interceptors.
+// Basically syntactic sugar.
+//
+// Deprecated: use google.golang.org/grpc.ChainStreamInterceptor instead.
+func WithStreamServerChain(interceptors ...grpc.StreamServerInterceptor) grpc.ServerOption {
+	return grpc.ChainStreamInterceptor(interceptors...)
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/doc.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/doc.go
new file mode 100644
index 0000000..718e100
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/doc.go
@@ -0,0 +1,69 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+/*
+`grpc_middleware` is a collection of gRPC middleware packages: interceptors, helpers and tools.
+
+Middleware
+
+gRPC is a fantastic RPC middleware, which sees a lot of adoption in the Golang world. However, the
+upstream gRPC codebase is relatively bare bones.
+
+This package, and most of its child packages provides commonly needed middleware for gRPC:
+client-side interceptors for retires, server-side interceptors for input validation and auth,
+functions for chaining said interceptors, metadata convenience methods and more.
+
+Chaining
+
+By default, gRPC doesn't allow one to have more than one interceptor either on the client nor on
+the server side. `grpc_middleware` provides convenient chaining methods
+
+Simple way of turning a multiple interceptors into a single interceptor. Here's an example for
+server chaining:
+
+	myServer := grpc.NewServer(
+	    grpc.StreamInterceptor(grpc_middleware.ChainStreamServer(loggingStream, monitoringStream, authStream)),
+	    grpc.UnaryInterceptor(grpc_middleware.ChainUnaryServer(loggingUnary, monitoringUnary, authUnary)),
+	)
+
+These interceptors will be executed from left to right: logging, monitoring and auth.
+
+Here's an example for client side chaining:
+
+	clientConn, err = grpc.Dial(
+	    address,
+	        grpc.WithUnaryInterceptor(grpc_middleware.ChainUnaryClient(monitoringClientUnary, retryUnary)),
+	        grpc.WithStreamInterceptor(grpc_middleware.ChainStreamClient(monitoringClientStream, retryStream)),
+	)
+	client = pb_testproto.NewTestServiceClient(clientConn)
+	resp, err := client.PingEmpty(s.ctx, &myservice.Request{Msg: "hello"})
+
+These interceptors will be executed from left to right: monitoring and then retry logic.
+
+The retry interceptor will call every interceptor that follows it whenever when a retry happens.
+
+Writing Your Own
+
+Implementing your own interceptor is pretty trivial: there are interfaces for that. But the interesting
+bit exposing common data to handlers (and other middleware), similarly to HTTP Middleware design.
+For example, you may want to pass the identity of the caller from the auth interceptor all the way
+to the handling function.
+
+For example, a client side interceptor example for auth looks like:
+
+	func FakeAuthUnaryInterceptor(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+	   newCtx := context.WithValue(ctx, "user_id", "john@example.com")
+	   return handler(newCtx, req)
+	}
+
+Unfortunately, it's not as easy for streaming RPCs. These have the `context.Context` embedded within
+the `grpc.ServerStream` object. To pass values through context, a wrapper (`WrappedServerStream`) is
+needed. For example:
+
+	func FakeAuthStreamingInterceptor(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+	   newStream := grpc_middleware.WrapServerStream(stream)
+	   newStream.WrappedContext = context.WithValue(ctx, "user_id", "john@example.com")
+	   return handler(srv, newStream)
+	}
+*/
+package grpc_middleware
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/makefile b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/makefile
new file mode 100644
index 0000000..b18d2d2
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/makefile
@@ -0,0 +1,17 @@
+SHELL=/bin/bash
+
+GOFILES_NOVENDOR = $(shell go list ./... | grep -v /vendor/)
+
+all: vet fmt test
+
+fmt:
+	go fmt $(GOFILES_NOVENDOR)
+
+vet:
+	# do not check lostcancel, they are intentional.
+	go vet -lostcancel=false $(GOFILES_NOVENDOR)
+
+test: vet
+	./scripts/test_all.sh
+
+.PHONY: all test
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/slack.png b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/slack.png
new file mode 100644
index 0000000..cc8f9a6
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/slack.png
Binary files differ
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/wrappers.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/wrappers.go
new file mode 100644
index 0000000..05ccfb3
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/wrappers.go
@@ -0,0 +1,30 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_middleware
+
+import (
+	"context"
+
+	"google.golang.org/grpc"
+)
+
+// WrappedServerStream is a thin wrapper around grpc.ServerStream that allows modifying context.
+type WrappedServerStream struct {
+	grpc.ServerStream
+	// WrappedContext is the wrapper's own Context. You can assign it.
+	WrappedContext context.Context
+}
+
+// Context returns the wrapper's WrappedContext, overwriting the nested grpc.ServerStream.Context()
+func (w *WrappedServerStream) Context() context.Context {
+	return w.WrappedContext
+}
+
+// WrapServerStream returns a ServerStream that has the ability to overwrite context.
+func WrapServerStream(stream grpc.ServerStream) *WrappedServerStream {
+	if existing, ok := stream.(*WrappedServerStream); ok {
+		return existing
+	}
+	return &WrappedServerStream{ServerStream: stream, WrappedContext: stream.Context()}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/.gitignore b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/.gitignore
new file mode 100644
index 0000000..2233cff
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/.gitignore
@@ -0,0 +1,201 @@
+#vendor
+vendor/
+
+# Created by .ignore support plugin (hsz.mobi)
+coverage.txt
+### Go template
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test
+*.prof
+### Windows template
+# Windows image file caches
+Thumbs.db
+ehthumbs.db
+
+# Folder config file
+Desktop.ini
+
+# Recycle Bin used on file shares
+$RECYCLE.BIN/
+
+# Windows Installer files
+*.cab
+*.msi
+*.msm
+*.msp
+
+# Windows shortcuts
+*.lnk
+### Kate template
+# Swap Files #
+.*.kate-swp
+.swp.*
+### SublimeText template
+# cache files for sublime text
+*.tmlanguage.cache
+*.tmPreferences.cache
+*.stTheme.cache
+
+# workspace files are user-specific
+*.sublime-workspace
+
+# project files should be checked into the repository, unless a significant
+# proportion of contributors will probably not be using SublimeText
+# *.sublime-project
+
+# sftp configuration file
+sftp-config.json
+### Linux template
+*~
+
+# temporary files which can be created if a process still has a handle open of a deleted file
+.fuse_hidden*
+
+# KDE directory preferences
+.directory
+
+# Linux trash folder which might appear on any partition or disk
+.Trash-*
+### JetBrains template
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio and Webstorm
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff:
+.idea
+.idea/tasks.xml
+.idea/dictionaries
+.idea/vcs.xml
+.idea/jsLibraryMappings.xml
+
+# Sensitive or high-churn files:
+.idea/dataSources.ids
+.idea/dataSources.xml
+.idea/dataSources.local.xml
+.idea/sqlDataSources.xml
+.idea/dynamic.xml
+.idea/uiDesigner.xml
+
+# Gradle:
+.idea/gradle.xml
+.idea/libraries
+
+# Mongo Explorer plugin:
+.idea/mongoSettings.xml
+
+## File-based project format:
+*.iws
+
+## Plugin-specific files:
+
+# IntelliJ
+/out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+### Xcode template
+# Xcode
+#
+# gitignore contributors: remember to update Global/Xcode.gitignore, Objective-C.gitignore & Swift.gitignore
+
+## Build generated
+build/
+DerivedData/
+
+## Various settings
+*.pbxuser
+!default.pbxuser
+*.mode1v3
+!default.mode1v3
+*.mode2v3
+!default.mode2v3
+*.perspectivev3
+!default.perspectivev3
+xcuserdata/
+
+## Other
+*.moved-aside
+*.xccheckout
+*.xcscmblueprint
+### Eclipse template
+
+.metadata
+bin/
+tmp/
+*.tmp
+*.bak
+*.swp
+*~.nib
+local.properties
+.settings/
+.loadpath
+.recommenders
+
+# Eclipse Core
+.project
+
+# External tool builders
+.externalToolBuilders/
+
+# Locally stored "Eclipse launch configurations"
+*.launch
+
+# PyDev specific (Python IDE for Eclipse)
+*.pydevproject
+
+# CDT-specific (C/C++ Development Tooling)
+.cproject
+
+# JDT-specific (Eclipse Java Development Tools)
+.classpath
+
+# Java annotation processor (APT)
+.factorypath
+
+# PDT-specific (PHP Development Tools)
+.buildpath
+
+# sbteclipse plugin
+.target
+
+# Tern plugin
+.tern-project
+
+# TeXlipse plugin
+.texlipse
+
+# STS (Spring Tool Suite)
+.springBeans
+
+# Code Recommenders
+.recommenders/
+
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/.travis.yml b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/.travis.yml
new file mode 100644
index 0000000..2a845b9
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/.travis.yml
@@ -0,0 +1,25 @@
+sudo: false
+language: go
+# * github.com/grpc/grpc-go still supports go1.6
+#   - When we drop support for go1.6 we can remove golang.org/x/net/context
+#     below as it is part of the Go std library since go1.7
+# * github.com/prometheus/client_golang already requires at least go1.7 since
+#   September 2017
+go:
+  - 1.6.x
+  - 1.7.x
+  - 1.8.x
+  - 1.9.x
+  - 1.10.x
+  - master
+
+install:
+  - go get github.com/prometheus/client_golang/prometheus
+  - go get google.golang.org/grpc
+  - go get golang.org/x/net/context
+  - go get github.com/stretchr/testify
+script:
+ - make test 
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/CHANGELOG.md b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/CHANGELOG.md
new file mode 100644
index 0000000..19a8059
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/CHANGELOG.md
@@ -0,0 +1,24 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [1.2.0](https://github.com/grpc-ecosystem/go-grpc-prometheus/releases/tag/v1.2.0) - 2018-06-04
+
+### Added
+
+* Provide metrics object as `prometheus.Collector`, for conventional metric registration.
+* Support non-default/global Prometheus registry.
+* Allow configuring counters with `prometheus.CounterOpts`.
+
+### Changed
+
+* Remove usage of deprecated `grpc.Code()`.
+* Remove usage of deprecated `grpc.Errorf` and replace with `status.Errorf`.
+
+---
+
+This changelog was started with version `v1.2.0`, for earlier versions refer to the respective [GitHub releases](https://github.com/grpc-ecosystem/go-grpc-prometheus/releases).
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/LICENSE b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/LICENSE
new file mode 100644
index 0000000..b2b0650
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/LICENSE
@@ -0,0 +1,201 @@
+                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
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+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
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+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   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.
\ No newline at end of file
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/README.md b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/README.md
new file mode 100644
index 0000000..499c583
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/README.md
@@ -0,0 +1,247 @@
+# Go gRPC Interceptors for Prometheus monitoring 
+
+[![Travis Build](https://travis-ci.org/grpc-ecosystem/go-grpc-prometheus.svg)](https://travis-ci.org/grpc-ecosystem/go-grpc-prometheus)
+[![Go Report Card](https://goreportcard.com/badge/github.com/grpc-ecosystem/go-grpc-prometheus)](http://goreportcard.com/report/grpc-ecosystem/go-grpc-prometheus)
+[![GoDoc](http://img.shields.io/badge/GoDoc-Reference-blue.svg)](https://godoc.org/github.com/grpc-ecosystem/go-grpc-prometheus)
+[![SourceGraph](https://sourcegraph.com/github.com/grpc-ecosystem/go-grpc-prometheus/-/badge.svg)](https://sourcegraph.com/github.com/grpc-ecosystem/go-grpc-prometheus/?badge)
+[![codecov](https://codecov.io/gh/grpc-ecosystem/go-grpc-prometheus/branch/master/graph/badge.svg)](https://codecov.io/gh/grpc-ecosystem/go-grpc-prometheus)
+[![Apache 2.0 License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](LICENSE)
+
+[Prometheus](https://prometheus.io/) monitoring for your [gRPC Go](https://github.com/grpc/grpc-go) servers and clients.
+
+A sister implementation for [gRPC Java](https://github.com/grpc/grpc-java) (same metrics, same semantics) is in [grpc-ecosystem/java-grpc-prometheus](https://github.com/grpc-ecosystem/java-grpc-prometheus).
+
+## Interceptors
+
+[gRPC Go](https://github.com/grpc/grpc-go) recently acquired support for Interceptors, i.e. middleware that is executed
+by a gRPC Server before the request is passed onto the user's application logic. It is a perfect way to implement
+common patterns: auth, logging and... monitoring.
+
+To use Interceptors in chains, please see [`go-grpc-middleware`](https://github.com/mwitkow/go-grpc-middleware).
+
+## Usage
+
+There are two types of interceptors: client-side and server-side. This package provides monitoring Interceptors for both.
+
+### Server-side
+
+```go
+import "github.com/grpc-ecosystem/go-grpc-prometheus"
+...
+    // Initialize your gRPC server's interceptor.
+    myServer := grpc.NewServer(
+        grpc.StreamInterceptor(grpc_prometheus.StreamServerInterceptor),
+        grpc.UnaryInterceptor(grpc_prometheus.UnaryServerInterceptor),
+    )
+    // Register your gRPC service implementations.
+    myservice.RegisterMyServiceServer(s.server, &myServiceImpl{})
+    // After all your registrations, make sure all of the Prometheus metrics are initialized.
+    grpc_prometheus.Register(myServer)
+    // Register Prometheus metrics handler.    
+    http.Handle("/metrics", promhttp.Handler())
+...
+```
+
+### Client-side
+
+```go
+import "github.com/grpc-ecosystem/go-grpc-prometheus"
+...
+   clientConn, err = grpc.Dial(
+       address,
+		   grpc.WithUnaryInterceptor(grpc_prometheus.UnaryClientInterceptor),
+		   grpc.WithStreamInterceptor(grpc_prometheus.StreamClientInterceptor)
+   )
+   client = pb_testproto.NewTestServiceClient(clientConn)
+   resp, err := client.PingEmpty(s.ctx, &myservice.Request{Msg: "hello"})
+...
+```
+
+# Metrics
+
+## Labels
+
+All server-side metrics start with `grpc_server` as Prometheus subsystem name. All client-side metrics start with `grpc_client`. Both of them have mirror-concepts. Similarly all methods
+contain the same rich labels:
+  
+  * `grpc_service` - the [gRPC service](http://www.grpc.io/docs/#defining-a-service) name, which is the combination of protobuf `package` and
+    the `grpc_service` section name. E.g. for `package = mwitkow.testproto` and 
+     `service TestService` the label will be `grpc_service="mwitkow.testproto.TestService"`
+  * `grpc_method` - the name of the method called on the gRPC service. E.g.  
+    `grpc_method="Ping"`
+  * `grpc_type` - the gRPC [type of request](http://www.grpc.io/docs/guides/concepts.html#rpc-life-cycle). 
+    Differentiating between the two is important especially for latency measurements.
+
+     - `unary` is single request, single response RPC
+     - `client_stream` is a multi-request, single response RPC
+     - `server_stream` is a single request, multi-response RPC
+     - `bidi_stream` is a multi-request, multi-response RPC
+    
+
+Additionally for completed RPCs, the following labels are used:
+
+  * `grpc_code` - the human-readable [gRPC status code](https://github.com/grpc/grpc-go/blob/master/codes/codes.go).
+    The list of all statuses is to long, but here are some common ones:
+      
+      - `OK` - means the RPC was successful
+      - `IllegalArgument` - RPC contained bad values
+      - `Internal` - server-side error not disclosed to the clients
+      
+## Counters
+
+The counters and their up to date documentation is in [server_reporter.go](server_reporter.go) and [client_reporter.go](client_reporter.go) 
+the respective Prometheus handler (usually `/metrics`). 
+
+For the purpose of this documentation we will only discuss `grpc_server` metrics. The `grpc_client` ones contain mirror concepts.
+
+For simplicity, let's assume we're tracking a single server-side RPC call of [`mwitkow.testproto.TestService`](examples/testproto/test.proto),
+calling the method `PingList`. The call succeeds and returns 20 messages in the stream.
+
+First, immediately after the server receives the call it will increment the
+`grpc_server_started_total` and start the handling time clock (if histograms are enabled). 
+
+```jsoniq
+grpc_server_started_total{grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream"} 1
+```
+
+Then the user logic gets invoked. It receives one message from the client containing the request 
+(it's a `server_stream`):
+
+```jsoniq
+grpc_server_msg_received_total{grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream"} 1
+```
+
+The user logic may return an error, or send multiple messages back to the client. In this case, on 
+each of the 20 messages sent back, a counter will be incremented:
+
+```jsoniq
+grpc_server_msg_sent_total{grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream"} 20
+```
+
+After the call completes, its status (`OK` or other [gRPC status code](https://github.com/grpc/grpc-go/blob/master/codes/codes.go)) 
+and the relevant call labels increment the `grpc_server_handled_total` counter.
+
+```jsoniq
+grpc_server_handled_total{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream"} 1
+```
+
+## Histograms
+
+[Prometheus histograms](https://prometheus.io/docs/concepts/metric_types/#histogram) are a great way
+to measure latency distributions of your RPCs. However, since it is bad practice to have metrics
+of [high cardinality](https://prometheus.io/docs/practices/instrumentation/#do-not-overuse-labels)
+the latency monitoring metrics are disabled by default. To enable them please call the following
+in your server initialization code:
+
+```jsoniq
+grpc_prometheus.EnableHandlingTimeHistogram()
+```
+
+After the call completes, its handling time will be recorded in a [Prometheus histogram](https://prometheus.io/docs/concepts/metric_types/#histogram)
+variable `grpc_server_handling_seconds`. The histogram variable contains three sub-metrics:
+
+ * `grpc_server_handling_seconds_count` - the count of all completed RPCs by status and method 
+ * `grpc_server_handling_seconds_sum` - cumulative time of RPCs by status and method, useful for 
+   calculating average handling times
+ * `grpc_server_handling_seconds_bucket` - contains the counts of RPCs by status and method in respective
+   handling-time buckets. These buckets can be used by Prometheus to estimate SLAs (see [here](https://prometheus.io/docs/practices/histograms/))
+
+The counter values will look as follows:
+
+```jsoniq
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="0.005"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="0.01"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="0.025"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="0.05"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="0.1"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="0.25"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="0.5"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="1"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="2.5"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="5"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="10"} 1
+grpc_server_handling_seconds_bucket{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream",le="+Inf"} 1
+grpc_server_handling_seconds_sum{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream"} 0.0003866430000000001
+grpc_server_handling_seconds_count{grpc_code="OK",grpc_method="PingList",grpc_service="mwitkow.testproto.TestService",grpc_type="server_stream"} 1
+```
+
+
+## Useful query examples
+
+Prometheus philosophy is to provide raw metrics to the monitoring system, and
+let the aggregations be handled there. The verbosity of above metrics make it possible to have that
+flexibility. Here's a couple of useful monitoring queries:
+
+
+### request inbound rate
+```jsoniq
+sum(rate(grpc_server_started_total{job="foo"}[1m])) by (grpc_service)
+```
+For `job="foo"` (common label to differentiate between Prometheus monitoring targets), calculate the
+rate of requests per second (1 minute window) for each gRPC `grpc_service` that the job has. Please note
+how the `grpc_method` is being omitted here: all methods of a given gRPC service will be summed together.
+
+### unary request error rate
+```jsoniq
+sum(rate(grpc_server_handled_total{job="foo",grpc_type="unary",grpc_code!="OK"}[1m])) by (grpc_service)
+```
+For `job="foo"`, calculate the per-`grpc_service` rate of `unary` (1:1) RPCs that failed, i.e. the 
+ones that didn't finish with `OK` code.
+
+### unary request error percentage
+```jsoniq
+sum(rate(grpc_server_handled_total{job="foo",grpc_type="unary",grpc_code!="OK"}[1m])) by (grpc_service)
+ / 
+sum(rate(grpc_server_started_total{job="foo",grpc_type="unary"}[1m])) by (grpc_service)
+ * 100.0
+```
+For `job="foo"`, calculate the percentage of failed requests by service. It's easy to notice that
+this is a combination of the two above examples. This is an example of a query you would like to
+[alert on](https://prometheus.io/docs/alerting/rules/) in your system for SLA violations, e.g.
+"no more than 1% requests should fail".
+
+### average response stream size
+```jsoniq
+sum(rate(grpc_server_msg_sent_total{job="foo",grpc_type="server_stream"}[10m])) by (grpc_service)
+ /
+sum(rate(grpc_server_started_total{job="foo",grpc_type="server_stream"}[10m])) by (grpc_service)
+```
+For `job="foo"` what is the `grpc_service`-wide `10m` average of messages returned for all `
+server_stream` RPCs. This allows you to track the stream sizes returned by your system, e.g. allows 
+you to track when clients started to send "wide" queries that ret
+Note the divisor is the number of started RPCs, in order to account for in-flight requests.
+
+### 99%-tile latency of unary requests
+```jsoniq
+histogram_quantile(0.99, 
+  sum(rate(grpc_server_handling_seconds_bucket{job="foo",grpc_type="unary"}[5m])) by (grpc_service,le)
+)
+```
+For `job="foo"`, returns an 99%-tile [quantile estimation](https://prometheus.io/docs/practices/histograms/#quantiles)
+of the handling time of RPCs per service. Please note the `5m` rate, this means that the quantile
+estimation will take samples in a rolling `5m` window. When combined with other quantiles
+(e.g. 50%, 90%), this query gives you tremendous insight into the responsiveness of your system 
+(e.g. impact of caching).
+
+### percentage of slow unary queries (>250ms)
+```jsoniq
+100.0 - (
+sum(rate(grpc_server_handling_seconds_bucket{job="foo",grpc_type="unary",le="0.25"}[5m])) by (grpc_service)
+ / 
+sum(rate(grpc_server_handling_seconds_count{job="foo",grpc_type="unary"}[5m])) by (grpc_service)
+) * 100.0
+```
+For `job="foo"` calculate the by-`grpc_service` fraction of slow requests that took longer than `0.25` 
+seconds. This query is relatively complex, since the Prometheus aggregations use `le` (less or equal)
+buckets, meaning that counting "fast" requests fractions is easier. However, simple maths helps.
+This is an example of a query you would like to alert on in your system for SLA violations, 
+e.g. "less than 1% of requests are slower than 250ms".
+
+
+## Status
+
+This code has been used since August 2015 as the basis for monitoring of *production* gRPC micro services  at [Improbable](https://improbable.io).
+
+## License
+
+`go-grpc-prometheus` is released under the Apache 2.0 license. See the [LICENSE](LICENSE) file for details.
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/client.go b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/client.go
new file mode 100644
index 0000000..751a4c7
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/client.go
@@ -0,0 +1,39 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+// gRPC Prometheus monitoring interceptors for client-side gRPC.
+
+package grpc_prometheus
+
+import (
+	prom "github.com/prometheus/client_golang/prometheus"
+)
+
+var (
+	// DefaultClientMetrics is the default instance of ClientMetrics. It is
+	// intended to be used in conjunction the default Prometheus metrics
+	// registry.
+	DefaultClientMetrics = NewClientMetrics()
+
+	// UnaryClientInterceptor is a gRPC client-side interceptor that provides Prometheus monitoring for Unary RPCs.
+	UnaryClientInterceptor = DefaultClientMetrics.UnaryClientInterceptor()
+
+	// StreamClientInterceptor is a gRPC client-side interceptor that provides Prometheus monitoring for Streaming RPCs.
+	StreamClientInterceptor = DefaultClientMetrics.StreamClientInterceptor()
+)
+
+func init() {
+	prom.MustRegister(DefaultClientMetrics.clientStartedCounter)
+	prom.MustRegister(DefaultClientMetrics.clientHandledCounter)
+	prom.MustRegister(DefaultClientMetrics.clientStreamMsgReceived)
+	prom.MustRegister(DefaultClientMetrics.clientStreamMsgSent)
+}
+
+// EnableClientHandlingTimeHistogram turns on recording of handling time of
+// RPCs. Histogram metrics can be very expensive for Prometheus to retain and
+// query. This function acts on the DefaultClientMetrics variable and the
+// default Prometheus metrics registry.
+func EnableClientHandlingTimeHistogram(opts ...HistogramOption) {
+	DefaultClientMetrics.EnableClientHandlingTimeHistogram(opts...)
+	prom.Register(DefaultClientMetrics.clientHandledHistogram)
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/client_metrics.go b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/client_metrics.go
new file mode 100644
index 0000000..9b476f9
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/client_metrics.go
@@ -0,0 +1,170 @@
+package grpc_prometheus
+
+import (
+	"io"
+
+	prom "github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+// ClientMetrics represents a collection of metrics to be registered on a
+// Prometheus metrics registry for a gRPC client.
+type ClientMetrics struct {
+	clientStartedCounter          *prom.CounterVec
+	clientHandledCounter          *prom.CounterVec
+	clientStreamMsgReceived       *prom.CounterVec
+	clientStreamMsgSent           *prom.CounterVec
+	clientHandledHistogramEnabled bool
+	clientHandledHistogramOpts    prom.HistogramOpts
+	clientHandledHistogram        *prom.HistogramVec
+}
+
+// NewClientMetrics returns a ClientMetrics object. Use a new instance of
+// ClientMetrics when not using the default Prometheus metrics registry, for
+// example when wanting to control which metrics are added to a registry as
+// opposed to automatically adding metrics via init functions.
+func NewClientMetrics(counterOpts ...CounterOption) *ClientMetrics {
+	opts := counterOptions(counterOpts)
+	return &ClientMetrics{
+		clientStartedCounter: prom.NewCounterVec(
+			opts.apply(prom.CounterOpts{
+				Name: "grpc_client_started_total",
+				Help: "Total number of RPCs started on the client.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+
+		clientHandledCounter: prom.NewCounterVec(
+			opts.apply(prom.CounterOpts{
+				Name: "grpc_client_handled_total",
+				Help: "Total number of RPCs completed by the client, regardless of success or failure.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method", "grpc_code"}),
+
+		clientStreamMsgReceived: prom.NewCounterVec(
+			opts.apply(prom.CounterOpts{
+				Name: "grpc_client_msg_received_total",
+				Help: "Total number of RPC stream messages received by the client.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+
+		clientStreamMsgSent: prom.NewCounterVec(
+			opts.apply(prom.CounterOpts{
+				Name: "grpc_client_msg_sent_total",
+				Help: "Total number of gRPC stream messages sent by the client.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+
+		clientHandledHistogramEnabled: false,
+		clientHandledHistogramOpts: prom.HistogramOpts{
+			Name:    "grpc_client_handling_seconds",
+			Help:    "Histogram of response latency (seconds) of the gRPC until it is finished by the application.",
+			Buckets: prom.DefBuckets,
+		},
+		clientHandledHistogram: nil,
+	}
+}
+
+// Describe sends the super-set of all possible descriptors of metrics
+// collected by this Collector to the provided channel and returns once
+// the last descriptor has been sent.
+func (m *ClientMetrics) Describe(ch chan<- *prom.Desc) {
+	m.clientStartedCounter.Describe(ch)
+	m.clientHandledCounter.Describe(ch)
+	m.clientStreamMsgReceived.Describe(ch)
+	m.clientStreamMsgSent.Describe(ch)
+	if m.clientHandledHistogramEnabled {
+		m.clientHandledHistogram.Describe(ch)
+	}
+}
+
+// Collect is called by the Prometheus registry when collecting
+// metrics. The implementation sends each collected metric via the
+// provided channel and returns once the last metric has been sent.
+func (m *ClientMetrics) Collect(ch chan<- prom.Metric) {
+	m.clientStartedCounter.Collect(ch)
+	m.clientHandledCounter.Collect(ch)
+	m.clientStreamMsgReceived.Collect(ch)
+	m.clientStreamMsgSent.Collect(ch)
+	if m.clientHandledHistogramEnabled {
+		m.clientHandledHistogram.Collect(ch)
+	}
+}
+
+// EnableClientHandlingTimeHistogram turns on recording of handling time of RPCs.
+// Histogram metrics can be very expensive for Prometheus to retain and query.
+func (m *ClientMetrics) EnableClientHandlingTimeHistogram(opts ...HistogramOption) {
+	for _, o := range opts {
+		o(&m.clientHandledHistogramOpts)
+	}
+	if !m.clientHandledHistogramEnabled {
+		m.clientHandledHistogram = prom.NewHistogramVec(
+			m.clientHandledHistogramOpts,
+			[]string{"grpc_type", "grpc_service", "grpc_method"},
+		)
+	}
+	m.clientHandledHistogramEnabled = true
+}
+
+// UnaryClientInterceptor is a gRPC client-side interceptor that provides Prometheus monitoring for Unary RPCs.
+func (m *ClientMetrics) UnaryClientInterceptor() func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+	return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+		monitor := newClientReporter(m, Unary, method)
+		monitor.SentMessage()
+		err := invoker(ctx, method, req, reply, cc, opts...)
+		if err != nil {
+			monitor.ReceivedMessage()
+		}
+		st, _ := status.FromError(err)
+		monitor.Handled(st.Code())
+		return err
+	}
+}
+
+// StreamClientInterceptor is a gRPC client-side interceptor that provides Prometheus monitoring for Streaming RPCs.
+func (m *ClientMetrics) StreamClientInterceptor() func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
+	return func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
+		monitor := newClientReporter(m, clientStreamType(desc), method)
+		clientStream, err := streamer(ctx, desc, cc, method, opts...)
+		if err != nil {
+			st, _ := status.FromError(err)
+			monitor.Handled(st.Code())
+			return nil, err
+		}
+		return &monitoredClientStream{clientStream, monitor}, nil
+	}
+}
+
+func clientStreamType(desc *grpc.StreamDesc) grpcType {
+	if desc.ClientStreams && !desc.ServerStreams {
+		return ClientStream
+	} else if !desc.ClientStreams && desc.ServerStreams {
+		return ServerStream
+	}
+	return BidiStream
+}
+
+// monitoredClientStream wraps grpc.ClientStream allowing each Sent/Recv of message to increment counters.
+type monitoredClientStream struct {
+	grpc.ClientStream
+	monitor *clientReporter
+}
+
+func (s *monitoredClientStream) SendMsg(m interface{}) error {
+	err := s.ClientStream.SendMsg(m)
+	if err == nil {
+		s.monitor.SentMessage()
+	}
+	return err
+}
+
+func (s *monitoredClientStream) RecvMsg(m interface{}) error {
+	err := s.ClientStream.RecvMsg(m)
+	if err == nil {
+		s.monitor.ReceivedMessage()
+	} else if err == io.EOF {
+		s.monitor.Handled(codes.OK)
+	} else {
+		st, _ := status.FromError(err)
+		s.monitor.Handled(st.Code())
+	}
+	return err
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/client_reporter.go b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/client_reporter.go
new file mode 100644
index 0000000..cbf1532
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/client_reporter.go
@@ -0,0 +1,46 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_prometheus
+
+import (
+	"time"
+
+	"google.golang.org/grpc/codes"
+)
+
+type clientReporter struct {
+	metrics     *ClientMetrics
+	rpcType     grpcType
+	serviceName string
+	methodName  string
+	startTime   time.Time
+}
+
+func newClientReporter(m *ClientMetrics, rpcType grpcType, fullMethod string) *clientReporter {
+	r := &clientReporter{
+		metrics: m,
+		rpcType: rpcType,
+	}
+	if r.metrics.clientHandledHistogramEnabled {
+		r.startTime = time.Now()
+	}
+	r.serviceName, r.methodName = splitMethodName(fullMethod)
+	r.metrics.clientStartedCounter.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+	return r
+}
+
+func (r *clientReporter) ReceivedMessage() {
+	r.metrics.clientStreamMsgReceived.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+}
+
+func (r *clientReporter) SentMessage() {
+	r.metrics.clientStreamMsgSent.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+}
+
+func (r *clientReporter) Handled(code codes.Code) {
+	r.metrics.clientHandledCounter.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName, code.String()).Inc()
+	if r.metrics.clientHandledHistogramEnabled {
+		r.metrics.clientHandledHistogram.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Observe(time.Since(r.startTime).Seconds())
+	}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/makefile b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/makefile
new file mode 100644
index 0000000..74c0842
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/makefile
@@ -0,0 +1,16 @@
+SHELL="/bin/bash"
+
+GOFILES_NOVENDOR = $(shell go list ./... | grep -v /vendor/)
+
+all: vet fmt test
+
+fmt:
+	go fmt $(GOFILES_NOVENDOR)
+
+vet:
+	go vet $(GOFILES_NOVENDOR)
+
+test: vet
+	./scripts/test_all.sh
+
+.PHONY: all vet test
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/metric_options.go b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/metric_options.go
new file mode 100644
index 0000000..9d51aec
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/metric_options.go
@@ -0,0 +1,41 @@
+package grpc_prometheus
+
+import (
+	prom "github.com/prometheus/client_golang/prometheus"
+)
+
+// A CounterOption lets you add options to Counter metrics using With* funcs.
+type CounterOption func(*prom.CounterOpts)
+
+type counterOptions []CounterOption
+
+func (co counterOptions) apply(o prom.CounterOpts) prom.CounterOpts {
+	for _, f := range co {
+		f(&o)
+	}
+	return o
+}
+
+// WithConstLabels allows you to add ConstLabels to Counter metrics.
+func WithConstLabels(labels prom.Labels) CounterOption {
+	return func(o *prom.CounterOpts) {
+		o.ConstLabels = labels
+	}
+}
+
+// A HistogramOption lets you add options to Histogram metrics using With*
+// funcs.
+type HistogramOption func(*prom.HistogramOpts)
+
+// WithHistogramBuckets allows you to specify custom bucket ranges for histograms if EnableHandlingTimeHistogram is on.
+func WithHistogramBuckets(buckets []float64) HistogramOption {
+	return func(o *prom.HistogramOpts) { o.Buckets = buckets }
+}
+
+// WithHistogramConstLabels allows you to add custom ConstLabels to
+// histograms metrics.
+func WithHistogramConstLabels(labels prom.Labels) HistogramOption {
+	return func(o *prom.HistogramOpts) {
+		o.ConstLabels = labels
+	}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server.go b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server.go
new file mode 100644
index 0000000..322f990
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server.go
@@ -0,0 +1,48 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+// gRPC Prometheus monitoring interceptors for server-side gRPC.
+
+package grpc_prometheus
+
+import (
+	prom "github.com/prometheus/client_golang/prometheus"
+	"google.golang.org/grpc"
+)
+
+var (
+	// DefaultServerMetrics is the default instance of ServerMetrics. It is
+	// intended to be used in conjunction the default Prometheus metrics
+	// registry.
+	DefaultServerMetrics = NewServerMetrics()
+
+	// UnaryServerInterceptor is a gRPC server-side interceptor that provides Prometheus monitoring for Unary RPCs.
+	UnaryServerInterceptor = DefaultServerMetrics.UnaryServerInterceptor()
+
+	// StreamServerInterceptor is a gRPC server-side interceptor that provides Prometheus monitoring for Streaming RPCs.
+	StreamServerInterceptor = DefaultServerMetrics.StreamServerInterceptor()
+)
+
+func init() {
+	prom.MustRegister(DefaultServerMetrics.serverStartedCounter)
+	prom.MustRegister(DefaultServerMetrics.serverHandledCounter)
+	prom.MustRegister(DefaultServerMetrics.serverStreamMsgReceived)
+	prom.MustRegister(DefaultServerMetrics.serverStreamMsgSent)
+}
+
+// Register takes a gRPC server and pre-initializes all counters to 0. This
+// allows for easier monitoring in Prometheus (no missing metrics), and should
+// be called *after* all services have been registered with the server. This
+// function acts on the DefaultServerMetrics variable.
+func Register(server *grpc.Server) {
+	DefaultServerMetrics.InitializeMetrics(server)
+}
+
+// EnableHandlingTimeHistogram turns on recording of handling time
+// of RPCs. Histogram metrics can be very expensive for Prometheus
+// to retain and query. This function acts on the DefaultServerMetrics
+// variable and the default Prometheus metrics registry.
+func EnableHandlingTimeHistogram(opts ...HistogramOption) {
+	DefaultServerMetrics.EnableHandlingTimeHistogram(opts...)
+	prom.Register(DefaultServerMetrics.serverHandledHistogram)
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server_metrics.go b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server_metrics.go
new file mode 100644
index 0000000..5b1467e
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server_metrics.go
@@ -0,0 +1,185 @@
+package grpc_prometheus
+
+import (
+	prom "github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/status"
+)
+
+// ServerMetrics represents a collection of metrics to be registered on a
+// Prometheus metrics registry for a gRPC server.
+type ServerMetrics struct {
+	serverStartedCounter          *prom.CounterVec
+	serverHandledCounter          *prom.CounterVec
+	serverStreamMsgReceived       *prom.CounterVec
+	serverStreamMsgSent           *prom.CounterVec
+	serverHandledHistogramEnabled bool
+	serverHandledHistogramOpts    prom.HistogramOpts
+	serverHandledHistogram        *prom.HistogramVec
+}
+
+// NewServerMetrics returns a ServerMetrics object. Use a new instance of
+// ServerMetrics when not using the default Prometheus metrics registry, for
+// example when wanting to control which metrics are added to a registry as
+// opposed to automatically adding metrics via init functions.
+func NewServerMetrics(counterOpts ...CounterOption) *ServerMetrics {
+	opts := counterOptions(counterOpts)
+	return &ServerMetrics{
+		serverStartedCounter: prom.NewCounterVec(
+			opts.apply(prom.CounterOpts{
+				Name: "grpc_server_started_total",
+				Help: "Total number of RPCs started on the server.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+		serverHandledCounter: prom.NewCounterVec(
+			opts.apply(prom.CounterOpts{
+				Name: "grpc_server_handled_total",
+				Help: "Total number of RPCs completed on the server, regardless of success or failure.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method", "grpc_code"}),
+		serverStreamMsgReceived: prom.NewCounterVec(
+			opts.apply(prom.CounterOpts{
+				Name: "grpc_server_msg_received_total",
+				Help: "Total number of RPC stream messages received on the server.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+		serverStreamMsgSent: prom.NewCounterVec(
+			opts.apply(prom.CounterOpts{
+				Name: "grpc_server_msg_sent_total",
+				Help: "Total number of gRPC stream messages sent by the server.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+		serverHandledHistogramEnabled: false,
+		serverHandledHistogramOpts: prom.HistogramOpts{
+			Name:    "grpc_server_handling_seconds",
+			Help:    "Histogram of response latency (seconds) of gRPC that had been application-level handled by the server.",
+			Buckets: prom.DefBuckets,
+		},
+		serverHandledHistogram: nil,
+	}
+}
+
+// EnableHandlingTimeHistogram enables histograms being registered when
+// registering the ServerMetrics on a Prometheus registry. Histograms can be
+// expensive on Prometheus servers. It takes options to configure histogram
+// options such as the defined buckets.
+func (m *ServerMetrics) EnableHandlingTimeHistogram(opts ...HistogramOption) {
+	for _, o := range opts {
+		o(&m.serverHandledHistogramOpts)
+	}
+	if !m.serverHandledHistogramEnabled {
+		m.serverHandledHistogram = prom.NewHistogramVec(
+			m.serverHandledHistogramOpts,
+			[]string{"grpc_type", "grpc_service", "grpc_method"},
+		)
+	}
+	m.serverHandledHistogramEnabled = true
+}
+
+// Describe sends the super-set of all possible descriptors of metrics
+// collected by this Collector to the provided channel and returns once
+// the last descriptor has been sent.
+func (m *ServerMetrics) Describe(ch chan<- *prom.Desc) {
+	m.serverStartedCounter.Describe(ch)
+	m.serverHandledCounter.Describe(ch)
+	m.serverStreamMsgReceived.Describe(ch)
+	m.serverStreamMsgSent.Describe(ch)
+	if m.serverHandledHistogramEnabled {
+		m.serverHandledHistogram.Describe(ch)
+	}
+}
+
+// Collect is called by the Prometheus registry when collecting
+// metrics. The implementation sends each collected metric via the
+// provided channel and returns once the last metric has been sent.
+func (m *ServerMetrics) Collect(ch chan<- prom.Metric) {
+	m.serverStartedCounter.Collect(ch)
+	m.serverHandledCounter.Collect(ch)
+	m.serverStreamMsgReceived.Collect(ch)
+	m.serverStreamMsgSent.Collect(ch)
+	if m.serverHandledHistogramEnabled {
+		m.serverHandledHistogram.Collect(ch)
+	}
+}
+
+// UnaryServerInterceptor is a gRPC server-side interceptor that provides Prometheus monitoring for Unary RPCs.
+func (m *ServerMetrics) UnaryServerInterceptor() func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+		monitor := newServerReporter(m, Unary, info.FullMethod)
+		monitor.ReceivedMessage()
+		resp, err := handler(ctx, req)
+		st, _ := status.FromError(err)
+		monitor.Handled(st.Code())
+		if err == nil {
+			monitor.SentMessage()
+		}
+		return resp, err
+	}
+}
+
+// StreamServerInterceptor is a gRPC server-side interceptor that provides Prometheus monitoring for Streaming RPCs.
+func (m *ServerMetrics) StreamServerInterceptor() func(srv interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+	return func(srv interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+		monitor := newServerReporter(m, streamRPCType(info), info.FullMethod)
+		err := handler(srv, &monitoredServerStream{ss, monitor})
+		st, _ := status.FromError(err)
+		monitor.Handled(st.Code())
+		return err
+	}
+}
+
+// InitializeMetrics initializes all metrics, with their appropriate null
+// value, for all gRPC methods registered on a gRPC server. This is useful, to
+// ensure that all metrics exist when collecting and querying.
+func (m *ServerMetrics) InitializeMetrics(server *grpc.Server) {
+	serviceInfo := server.GetServiceInfo()
+	for serviceName, info := range serviceInfo {
+		for _, mInfo := range info.Methods {
+			preRegisterMethod(m, serviceName, &mInfo)
+		}
+	}
+}
+
+func streamRPCType(info *grpc.StreamServerInfo) grpcType {
+	if info.IsClientStream && !info.IsServerStream {
+		return ClientStream
+	} else if !info.IsClientStream && info.IsServerStream {
+		return ServerStream
+	}
+	return BidiStream
+}
+
+// monitoredStream wraps grpc.ServerStream allowing each Sent/Recv of message to increment counters.
+type monitoredServerStream struct {
+	grpc.ServerStream
+	monitor *serverReporter
+}
+
+func (s *monitoredServerStream) SendMsg(m interface{}) error {
+	err := s.ServerStream.SendMsg(m)
+	if err == nil {
+		s.monitor.SentMessage()
+	}
+	return err
+}
+
+func (s *monitoredServerStream) RecvMsg(m interface{}) error {
+	err := s.ServerStream.RecvMsg(m)
+	if err == nil {
+		s.monitor.ReceivedMessage()
+	}
+	return err
+}
+
+// preRegisterMethod is invoked on Register of a Server, allowing all gRPC services labels to be pre-populated.
+func preRegisterMethod(metrics *ServerMetrics, serviceName string, mInfo *grpc.MethodInfo) {
+	methodName := mInfo.Name
+	methodType := string(typeFromMethodInfo(mInfo))
+	// These are just references (no increments), as just referencing will create the labels but not set values.
+	metrics.serverStartedCounter.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	metrics.serverStreamMsgReceived.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	metrics.serverStreamMsgSent.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	if metrics.serverHandledHistogramEnabled {
+		metrics.serverHandledHistogram.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	}
+	for _, code := range allCodes {
+		metrics.serverHandledCounter.GetMetricWithLabelValues(methodType, serviceName, methodName, code.String())
+	}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server_reporter.go b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server_reporter.go
new file mode 100644
index 0000000..aa9db54
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server_reporter.go
@@ -0,0 +1,46 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_prometheus
+
+import (
+	"time"
+
+	"google.golang.org/grpc/codes"
+)
+
+type serverReporter struct {
+	metrics     *ServerMetrics
+	rpcType     grpcType
+	serviceName string
+	methodName  string
+	startTime   time.Time
+}
+
+func newServerReporter(m *ServerMetrics, rpcType grpcType, fullMethod string) *serverReporter {
+	r := &serverReporter{
+		metrics: m,
+		rpcType: rpcType,
+	}
+	if r.metrics.serverHandledHistogramEnabled {
+		r.startTime = time.Now()
+	}
+	r.serviceName, r.methodName = splitMethodName(fullMethod)
+	r.metrics.serverStartedCounter.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+	return r
+}
+
+func (r *serverReporter) ReceivedMessage() {
+	r.metrics.serverStreamMsgReceived.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+}
+
+func (r *serverReporter) SentMessage() {
+	r.metrics.serverStreamMsgSent.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+}
+
+func (r *serverReporter) Handled(code codes.Code) {
+	r.metrics.serverHandledCounter.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName, code.String()).Inc()
+	if r.metrics.serverHandledHistogramEnabled {
+		r.metrics.serverHandledHistogram.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Observe(time.Since(r.startTime).Seconds())
+	}
+}
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/util.go b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/util.go
new file mode 100644
index 0000000..7987de3
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-prometheus/util.go
@@ -0,0 +1,50 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_prometheus
+
+import (
+	"strings"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+)
+
+type grpcType string
+
+const (
+	Unary        grpcType = "unary"
+	ClientStream grpcType = "client_stream"
+	ServerStream grpcType = "server_stream"
+	BidiStream   grpcType = "bidi_stream"
+)
+
+var (
+	allCodes = []codes.Code{
+		codes.OK, codes.Canceled, codes.Unknown, codes.InvalidArgument, codes.DeadlineExceeded, codes.NotFound,
+		codes.AlreadyExists, codes.PermissionDenied, codes.Unauthenticated, codes.ResourceExhausted,
+		codes.FailedPrecondition, codes.Aborted, codes.OutOfRange, codes.Unimplemented, codes.Internal,
+		codes.Unavailable, codes.DataLoss,
+	}
+)
+
+func splitMethodName(fullMethodName string) (string, string) {
+	fullMethodName = strings.TrimPrefix(fullMethodName, "/") // remove leading slash
+	if i := strings.Index(fullMethodName, "/"); i >= 0 {
+		return fullMethodName[:i], fullMethodName[i+1:]
+	}
+	return "unknown", "unknown"
+}
+
+func typeFromMethodInfo(mInfo *grpc.MethodInfo) grpcType {
+	if !mInfo.IsClientStream && !mInfo.IsServerStream {
+		return Unary
+	}
+	if mInfo.IsClientStream && !mInfo.IsServerStream {
+		return ClientStream
+	}
+	if !mInfo.IsClientStream && mInfo.IsServerStream {
+		return ServerStream
+	}
+	return BidiStream
+}