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mirror of https://github.com/chai2010/advanced-go-programming-book.git synced 2025-05-24 12:32:21 +00:00

vendor: add grpc-middleware v1.0.0, not include sub packages

This commit is contained in:
chai2010 2018-07-08 17:57:30 +08:00
parent c137e47ea5
commit f770fabf01
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vendor/README.md vendored
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@ -8,4 +8,6 @@ TODO
- [Protobuf](https://github.com/golang/protobuf): [v1.1.0](https://github.com/golang/protobuf/releases/tag/v1.1.0)
- [gRPC](https://github.com/grpc/grpc-go): [v1.13.0](https://github.com/grpc/grpc-go/releases/tag/v1.13.0)
- [grpc-gateway](https://github.com/grpc-ecosystem/grpc-gateway): [v1.4.1](https://github.com/grpc-ecosystem/grpc-gateway/releases/tag/v1.4.1)
- [grpc-middleware](https://github.com/grpc-ecosystem/go-grpc-middleware): [v1.0.0](https://github.com/grpc-ecosystem/go-grpc-middleware/releases/tag/v1.0.0)

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# 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
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Thumbs.db
ehthumbs.db
# Folder config file
Desktop.ini
# Recycle Bin used on file shares
$RECYCLE.BIN/
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*.cab
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*.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
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.Trash-*
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# 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
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# Sensitive or high-churn files:
.idea/dataSources.ids
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.idea/dataSources.local.xml
.idea/sqlDataSources.xml
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.idea/uiDesigner.xml
# Gradle:
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.idea/mongoSettings.xml
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# IntelliJ
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!default.pbxuser
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xcuserdata/
## Other
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*.launch
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# STS (Spring Tool Suite)
.springBeans
# Code Recommenders
.recommenders/
coverage.txt
#vendor
vendor/

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sudo: false
language: go
go:
- 1.8.x
env:
- DEP_VERSION="0.3.2"
before_install:
# Download the binary to bin folder in $GOPATH
- curl -L -s https://github.com/golang/dep/releases/download/v${DEP_VERSION}/dep-linux-amd64 -o $GOPATH/bin/dep
# Make the binary executable
- chmod +x $GOPATH/bin/dep
install:
- dep ensure
script:
- make checkdocs
- make test
after_success:
- bash <(curl -s https://codecov.io/bash)

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# 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.

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# grpc_middleware
`import "github.com/grpc-ecosystem/go-grpc-middleware"`
* [Overview](#pkg-overview)
* [Imported Packages](#pkg-imports)
* [Index](#pkg-index)
## <a name="pkg-overview">Overview</a>
`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, stream)
}
## <a name="pkg-imports">Imported Packages</a>
- [golang.org/x/net/context](https://godoc.org/golang.org/x/net/context)
- [google.golang.org/grpc](https://godoc.org/google.golang.org/grpc)
## <a name="pkg-index">Index</a>
* [func ChainStreamClient(interceptors ...grpc.StreamClientInterceptor) grpc.StreamClientInterceptor](#ChainStreamClient)
* [func ChainStreamServer(interceptors ...grpc.StreamServerInterceptor) grpc.StreamServerInterceptor](#ChainStreamServer)
* [func ChainUnaryClient(interceptors ...grpc.UnaryClientInterceptor) grpc.UnaryClientInterceptor](#ChainUnaryClient)
* [func ChainUnaryServer(interceptors ...grpc.UnaryServerInterceptor) grpc.UnaryServerInterceptor](#ChainUnaryServer)
* [func WithStreamServerChain(interceptors ...grpc.StreamServerInterceptor) grpc.ServerOption](#WithStreamServerChain)
* [func WithUnaryServerChain(interceptors ...grpc.UnaryServerInterceptor) grpc.ServerOption](#WithUnaryServerChain)
* [type WrappedServerStream](#WrappedServerStream)
* [func WrapServerStream(stream grpc.ServerStream) \*WrappedServerStream](#WrapServerStream)
* [func (w \*WrappedServerStream) Context() context.Context](#WrappedServerStream.Context)
#### <a name="pkg-files">Package files</a>
[chain.go](./chain.go) [doc.go](./doc.go) [wrappers.go](./wrappers.go)
## <a name="ChainStreamClient">func</a> [ChainStreamClient](./chain.go#L136)
``` go
func ChainStreamClient(interceptors ...grpc.StreamClientInterceptor) grpc.StreamClientInterceptor
```
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.
## <a name="ChainStreamServer">func</a> [ChainStreamServer](./chain.go#L58)
``` go
func ChainStreamServer(interceptors ...grpc.StreamServerInterceptor) grpc.StreamServerInterceptor
```
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.
## <a name="ChainUnaryClient">func</a> [ChainUnaryClient](./chain.go#L97)
``` go
func ChainUnaryClient(interceptors ...grpc.UnaryClientInterceptor) grpc.UnaryClientInterceptor
```
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.
## <a name="ChainUnaryServer">func</a> [ChainUnaryServer](./chain.go#L18)
``` go
func ChainUnaryServer(interceptors ...grpc.UnaryServerInterceptor) grpc.UnaryServerInterceptor
```
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.
## <a name="WithStreamServerChain">func</a> [WithStreamServerChain](./chain.go#L181)
``` go
func WithStreamServerChain(interceptors ...grpc.StreamServerInterceptor) grpc.ServerOption
```
WithStreamServerChain is a grpc.Server config option that accepts multiple stream interceptors.
Basically syntactic sugar.
## <a name="WithUnaryServerChain">func</a> [WithUnaryServerChain](./chain.go#L175)
``` go
func WithUnaryServerChain(interceptors ...grpc.UnaryServerInterceptor) grpc.ServerOption
```
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.
## <a name="WrappedServerStream">type</a> [WrappedServerStream](./wrappers.go#L12-L16)
``` go
type WrappedServerStream struct {
grpc.ServerStream
// WrappedContext is the wrapper's own Context. You can assign it.
WrappedContext context.Context
}
```
WrappedServerStream is a thin wrapper around grpc.ServerStream that allows modifying context.
### <a name="WrapServerStream">func</a> [WrapServerStream](./wrappers.go#L24)
``` go
func WrapServerStream(stream grpc.ServerStream) *WrappedServerStream
```
WrapServerStream returns a ServerStream that has the ability to overwrite context.
### <a name="WrappedServerStream.Context">func</a> (\*WrappedServerStream) [Context](./wrappers.go#L19)
``` go
func (w *WrappedServerStream) Context() context.Context
```
Context returns the wrapper's WrappedContext, overwriting the nested grpc.ServerStream.Context()
- - -
Generated by [godoc2ghmd](https://github.com/GandalfUK/godoc2ghmd)

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# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
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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,
unless required by applicable law (such as deliberate and grossly
negligent acts) or agreed to in writing, shall any Contributor be
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incidental, or consequential damages of any character arising as a
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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.
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the Work or Derivative Works thereof, You may choose to offer,
and charge a fee for, acceptance of support, warranty, indemnity,
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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.
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Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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# 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](slack.png)](https://join.slack.com/t/improbable-eng/shared_invite/enQtMzQ1ODcyMzQ5MjM4LWY5ZWZmNGM2ODc5MmViNmQ3ZTA3ZTY3NzQwOTBlMTkzZmIxZTIxODk0OWU3YjZhNWVlNDU3MDlkZGViZjhkMjc)
[gRPC Go](https://github.com/grpc/grpc-go) Middleware: interceptors, helpers, utilities.
**Important** The repo recently moved to `github.com/grpc-ecosystem/go-grpc-middleware`, please update your import paths.
## 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 either 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. See [Documentation](DOC.md), but 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.
#### 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
#### 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
## Status
This code has been running in *production* since May 2016 as the basis of the gRPC micro services stack at [Improbable](https://improbable.io).
Additional tooling will be added, and contributions are welcome.
## License
`go-grpc-middleware` is released under the Apache 2.0 license. See the [LICENSE](LICENSE) file for details.

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// Copyright 2016 Michal Witkowski. All Rights Reserved.
// See LICENSE for licensing terms.
// gRPC Server Interceptor chaining middleware.
package grpc_middleware
import (
"golang.org/x/net/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.
func ChainUnaryServer(interceptors ...grpc.UnaryServerInterceptor) grpc.UnaryServerInterceptor {
n := len(interceptors)
if n > 1 {
lastI := n - 1
return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
var (
chainHandler grpc.UnaryHandler
curI int
)
chainHandler = func(currentCtx context.Context, currentReq interface{}) (interface{}, error) {
if curI == lastI {
return handler(currentCtx, currentReq)
}
curI++
resp, err := interceptors[curI](currentCtx, currentReq, info, chainHandler)
curI--
return resp, err
}
return interceptors[0](ctx, req, info, chainHandler)
}
}
if n == 1 {
return interceptors[0]
}
// n == 0; Dummy interceptor maintained for backward compatibility to avoid returning nil.
return func(ctx context.Context, req interface{}, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
return handler(ctx, req)
}
}
// 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.
func ChainStreamServer(interceptors ...grpc.StreamServerInterceptor) grpc.StreamServerInterceptor {
n := len(interceptors)
if n > 1 {
lastI := n - 1
return func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
var (
chainHandler grpc.StreamHandler
curI int
)
chainHandler = func(currentSrv interface{}, currentStream grpc.ServerStream) error {
if curI == lastI {
return handler(currentSrv, currentStream)
}
curI++
err := interceptors[curI](currentSrv, currentStream, info, chainHandler)
curI--
return err
}
return interceptors[0](srv, stream, info, chainHandler)
}
}
if n == 1 {
return interceptors[0]
}
// n == 0; Dummy interceptor maintained for backward compatibility to avoid returning nil.
return func(srv interface{}, stream grpc.ServerStream, _ *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
return handler(srv, stream)
}
}
// 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)
if n > 1 {
lastI := n - 1
return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
var (
chainHandler grpc.UnaryInvoker
curI int
)
chainHandler = func(currentCtx context.Context, currentMethod string, currentReq, currentRepl interface{}, currentConn *grpc.ClientConn, currentOpts ...grpc.CallOption) error {
if curI == lastI {
return invoker(currentCtx, currentMethod, currentReq, currentRepl, currentConn, currentOpts...)
}
curI++
err := interceptors[curI](currentCtx, currentMethod, currentReq, currentRepl, currentConn, chainHandler, currentOpts...)
curI--
return err
}
return interceptors[0](ctx, method, req, reply, cc, chainHandler, opts...)
}
}
if n == 1 {
return interceptors[0]
}
// n == 0; Dummy interceptor maintained for backward compatibility to avoid returning nil.
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...)
}
}
// 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)
if n > 1 {
lastI := n - 1
return func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
var (
chainHandler grpc.Streamer
curI int
)
chainHandler = func(currentCtx context.Context, currentDesc *grpc.StreamDesc, currentConn *grpc.ClientConn, currentMethod string, currentOpts ...grpc.CallOption) (grpc.ClientStream, error) {
if curI == lastI {
return streamer(currentCtx, currentDesc, currentConn, currentMethod, currentOpts...)
}
curI++
stream, err := interceptors[curI](currentCtx, currentDesc, currentConn, currentMethod, chainHandler, currentOpts...)
curI--
return stream, err
}
return interceptors[0](ctx, desc, cc, method, chainHandler, opts...)
}
}
if n == 1 {
return interceptors[0]
}
// n == 0; Dummy interceptor maintained for backward compatibility to avoid returning nil.
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...)
}
}
// 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.
func WithUnaryServerChain(interceptors ...grpc.UnaryServerInterceptor) grpc.ServerOption {
return grpc.UnaryInterceptor(ChainUnaryServer(interceptors...))
}
// WithStreamServerChain is a grpc.Server config option that accepts multiple stream interceptors.
// Basically syntactic sugar.
func WithStreamServerChain(interceptors ...grpc.StreamServerInterceptor) grpc.ServerOption {
return grpc.StreamInterceptor(ChainStreamServer(interceptors...))
}

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// Copyright 2016 Michal Witkowski. All Rights Reserved.
// See LICENSE for licensing terms.
package grpc_middleware
import (
"fmt"
"testing"
"github.com/stretchr/testify/require"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/metadata"
)
var (
someServiceName = "SomeService.StreamMethod"
parentUnaryInfo = &grpc.UnaryServerInfo{FullMethod: someServiceName}
parentStreamInfo = &grpc.StreamServerInfo{
FullMethod: someServiceName,
IsServerStream: true,
}
someValue = 1
parentContext = context.WithValue(context.TODO(), "parent", someValue)
)
func TestChainUnaryServer(t *testing.T) {
input := "input"
output := "output"
first := func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
requireContextValue(t, ctx, "parent", "first interceptor must know the parent context value")
require.Equal(t, parentUnaryInfo, info, "first interceptor must know the someUnaryServerInfo")
ctx = context.WithValue(ctx, "first", 1)
return handler(ctx, req)
}
second := func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
requireContextValue(t, ctx, "parent", "second interceptor must know the parent context value")
requireContextValue(t, ctx, "first", "second interceptor must know the first context value")
require.Equal(t, parentUnaryInfo, info, "second interceptor must know the someUnaryServerInfo")
ctx = context.WithValue(ctx, "second", 1)
return handler(ctx, req)
}
handler := func(ctx context.Context, req interface{}) (interface{}, error) {
require.EqualValues(t, input, req, "handler must get the input")
requireContextValue(t, ctx, "parent", "handler must know the parent context value")
requireContextValue(t, ctx, "first", "handler must know the first context value")
requireContextValue(t, ctx, "second", "handler must know the second context value")
return output, nil
}
chain := ChainUnaryServer(first, second)
out, _ := chain(parentContext, input, parentUnaryInfo, handler)
require.EqualValues(t, output, out, "chain must return handler's output")
}
func TestChainStreamServer(t *testing.T) {
someService := &struct{}{}
recvMessage := "received"
sentMessage := "sent"
outputError := fmt.Errorf("some error")
first := func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
requireContextValue(t, stream.Context(), "parent", "first interceptor must know the parent context value")
require.Equal(t, parentStreamInfo, info, "first interceptor must know the parentStreamInfo")
require.Equal(t, someService, srv, "first interceptor must know someService")
wrapped := WrapServerStream(stream)
wrapped.WrappedContext = context.WithValue(stream.Context(), "first", 1)
return handler(srv, wrapped)
}
second := func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
requireContextValue(t, stream.Context(), "parent", "second interceptor must know the parent context value")
requireContextValue(t, stream.Context(), "parent", "second interceptor must know the first context value")
require.Equal(t, parentStreamInfo, info, "second interceptor must know the parentStreamInfo")
require.Equal(t, someService, srv, "second interceptor must know someService")
wrapped := WrapServerStream(stream)
wrapped.WrappedContext = context.WithValue(stream.Context(), "second", 1)
return handler(srv, wrapped)
}
handler := func(srv interface{}, stream grpc.ServerStream) error {
require.Equal(t, someService, srv, "handler must know someService")
requireContextValue(t, stream.Context(), "parent", "handler must know the parent context value")
requireContextValue(t, stream.Context(), "first", "handler must know the first context value")
requireContextValue(t, stream.Context(), "second", "handler must know the second context value")
require.NoError(t, stream.RecvMsg(recvMessage), "handler must have access to stream messages")
require.NoError(t, stream.SendMsg(sentMessage), "handler must be able to send stream messages")
return outputError
}
fakeStream := &fakeServerStream{ctx: parentContext, recvMessage: recvMessage}
chain := ChainStreamServer(first, second)
err := chain(someService, fakeStream, parentStreamInfo, handler)
require.Equal(t, outputError, err, "chain must return handler's error")
require.Equal(t, sentMessage, fakeStream.sentMessage, "handler's sent message must propagate to stream")
}
func TestChainUnaryClient(t *testing.T) {
ignoredMd := metadata.Pairs("foo", "bar")
parentOpts := []grpc.CallOption{grpc.Header(&ignoredMd)}
reqMessage := "request"
replyMessage := "reply"
outputError := fmt.Errorf("some error")
first := func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
requireContextValue(t, ctx, "parent", "first must know the parent context value")
require.Equal(t, someServiceName, method, "first must know someService")
require.Len(t, opts, 1, "first should see parent CallOptions")
wrappedCtx := context.WithValue(ctx, "first", 1)
return invoker(wrappedCtx, method, req, reply, cc, opts...)
}
second := func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
requireContextValue(t, ctx, "parent", "second must know the parent context value")
require.Equal(t, someServiceName, method, "second must know someService")
require.Len(t, opts, 1, "second should see parent CallOptions")
wrappedOpts := append(opts, grpc.FailFast(true))
wrappedCtx := context.WithValue(ctx, "second", 1)
return invoker(wrappedCtx, method, req, reply, cc, wrappedOpts...)
}
invoker := func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, opts ...grpc.CallOption) error {
require.Equal(t, someServiceName, method, "invoker must know someService")
requireContextValue(t, ctx, "parent", "invoker must know the parent context value")
requireContextValue(t, ctx, "first", "invoker must know the first context value")
requireContextValue(t, ctx, "second", "invoker must know the second context value")
require.Len(t, opts, 2, "invoker should see both CallOpts from second and parent")
return outputError
}
chain := ChainUnaryClient(first, second)
err := chain(parentContext, someServiceName, reqMessage, replyMessage, nil, invoker, parentOpts...)
require.Equal(t, outputError, err, "chain must return invokers's error")
}
func TestChainStreamClient(t *testing.T) {
ignoredMd := metadata.Pairs("foo", "bar")
parentOpts := []grpc.CallOption{grpc.Header(&ignoredMd)}
clientStream := &fakeClientStream{}
fakeStreamDesc := &grpc.StreamDesc{ClientStreams: true, ServerStreams: true, StreamName: someServiceName}
first := func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
requireContextValue(t, ctx, "parent", "first must know the parent context value")
require.Equal(t, someServiceName, method, "first must know someService")
require.Len(t, opts, 1, "first should see parent CallOptions")
wrappedCtx := context.WithValue(ctx, "first", 1)
return streamer(wrappedCtx, desc, cc, method, opts...)
}
second := func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
requireContextValue(t, ctx, "parent", "second must know the parent context value")
require.Equal(t, someServiceName, method, "second must know someService")
require.Len(t, opts, 1, "second should see parent CallOptions")
wrappedOpts := append(opts, grpc.FailFast(true))
wrappedCtx := context.WithValue(ctx, "second", 1)
return streamer(wrappedCtx, desc, cc, method, wrappedOpts...)
}
streamer := func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, opts ...grpc.CallOption) (grpc.ClientStream, error) {
require.Equal(t, someServiceName, method, "streamer must know someService")
require.Equal(t, fakeStreamDesc, desc, "streamer must see the right StreamDesc")
requireContextValue(t, ctx, "parent", "streamer must know the parent context value")
requireContextValue(t, ctx, "first", "streamer must know the first context value")
requireContextValue(t, ctx, "second", "streamer must know the second context value")
require.Len(t, opts, 2, "streamer should see both CallOpts from second and parent")
return clientStream, nil
}
chain := ChainStreamClient(first, second)
someStream, err := chain(parentContext, fakeStreamDesc, nil, someServiceName, streamer, parentOpts...)
require.NoError(t, err, "chain must not return an error as nothing there reutrned it")
require.Equal(t, clientStream, someStream, "chain must return invokers's clientstream")
}
func requireContextValue(t *testing.T, ctx context.Context, key string, msg ...interface{}) {
val := ctx.Value(key)
require.NotNil(t, val, msg...)
require.Equal(t, someValue, val, msg...)
}

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// 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, stream)
}
*/
package grpc_middleware

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SHELL="/bin/bash"
GOFILES_NOVENDOR = $(shell go list ./... | grep -v /vendor/)
all: vet fmt docs test
docs:
./scripts/docs.sh generate
checkdocs:
./scripts/docs.sh check
fmt:
go fmt $(GOFILES_NOVENDOR)
vet:
go vet $(GOFILES_NOVENDOR)
test: vet
./scripts/test_all.sh
.PHONY: all docs validate test

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// Copyright 2016 Michal Witkowski. All Rights Reserved.
// See LICENSE for licensing terms.
package grpc_middleware
import (
"golang.org/x/net/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()}
}

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// Copyright 2016 Michal Witkowski. All Rights Reserved.
// See LICENSE for licensing terms.
package grpc_middleware
import (
"testing"
"github.com/stretchr/testify/assert"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
)
func TestWrapServerStream(t *testing.T) {
ctx := context.WithValue(context.TODO(), "something", 1)
fake := &fakeServerStream{ctx: ctx}
wrapped := WrapServerStream(fake)
assert.NotNil(t, wrapped.Context().Value("something"), "values from fake must propagate to wrapper")
wrapped.WrappedContext = context.WithValue(wrapped.Context(), "other", 2)
assert.NotNil(t, wrapped.Context().Value("other"), "values from wrapper must be set")
}
type fakeServerStream struct {
grpc.ServerStream
ctx context.Context
recvMessage interface{}
sentMessage interface{}
}
func (f *fakeServerStream) Context() context.Context {
return f.ctx
}
func (f *fakeServerStream) SendMsg(m interface{}) error {
if f.sentMessage != nil {
return grpc.Errorf(codes.AlreadyExists, "fakeServerStream only takes one message, sorry")
}
f.sentMessage = m
return nil
}
func (f *fakeServerStream) RecvMsg(m interface{}) error {
if f.recvMessage == nil {
return grpc.Errorf(codes.NotFound, "fakeServerStream has no message, sorry")
}
return nil
}
type fakeClientStream struct {
grpc.ClientStream
}