1# Go gRPC Middleware V2
2
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8[![Apache 2.0 License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](LICENSE)
9[![quality: production](https://img.shields.io/badge/quality-production-orange.svg)](#status)
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11
12[gRPC Go](https://github.com/grpc/grpc-go) Middleware: interceptors, helpers, utilities.
13
14**NOTE: V2 is under development. If you want to be up to date, or better (!) help us improve go-grpc-middleware please follow on https://github.com/grpc-ecosystem/go-grpc-middleware/issues/275.**
15
16## Middleware
17
18[gRPC Go](https://github.com/grpc/grpc-go) recently acquired support for
19Interceptors, i.e. [middleware](https://medium.com/@matryer/writing-middleware-in-golang-and-how-go-makes-it-so-much-fun-4375c1246e81#.gv7tdlghs)
20that 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
21common patterns: auth, logging, message, validation, retries or monitoring.
22
23These are generic building blocks that make it easy to build multiple microservices easily.
24The purpose of this repository is to act as a go-to point for such reusable functionality. It contains
25some of them itself, but also will link to useful external repos.
26
27`middleware` itself provides support for chaining interceptors, here's an example:
28
29```go
30import "github.com/grpc-ecosystem/go-grpc-middleware/v2"
31
32myServer := grpc.NewServer(
33    grpc.StreamInterceptor(middleware.ChainStreamServer(
34        tags.StreamServerInterceptor(),
35        opentracing.StreamServerInterceptor(),
36        prometheus.StreamServerInterceptor,
37        zap.StreamServerInterceptor(zapLogger),
38        auth.StreamServerInterceptor(myAuthFunction),
39        recovery.StreamServerInterceptor(),
40    )),
41    grpc.UnaryInterceptor(middleware.ChainUnaryServer(
42        tags.UnaryServerInterceptor(),
43        opentracing.UnaryServerInterceptor(),
44        prometheus.UnaryServerInterceptor,
45        zap.UnaryServerInterceptor(zapLogger),
46        auth.UnaryServerInterceptor(myAuthFunction),
47        recovery.UnaryServerInterceptor(),
48    )),
49)
50```
51
52## Interceptors
53
54*Please send a PR to add new interceptors or middleware to this list*
55
56#### Auth
57   * [`auth`](auth) - a customizable (via `AuthFunc`) piece of auth middleware
58
59#### Logging
60   * [`tags`](interceptors/tags) - a library that adds a `Tag` map to context, with data populated from request body
61   * [`zap`](providers/zap) - integration of [zap](https://github.com/uber-go/zap) logging library into gRPC handlers.
62   * [`logrus`](providers/logrus) - integration of [logrus](https://github.com/sirupsen/logrus) logging library into gRPC handlers.
63   * [`kit`](providers/kit) - integration of [go-kit](https://github.com/go-kit/kit/tree/master/log) logging library into gRPC handlers.
64   * [`zerolog`](providers/zerolog) - integration of [zerolog](https://github.com/rs/zerolog) logging Library into gRPC handlers.
65
66#### Monitoring
67   * [`grpc_prometheus`⚡](https://github.com/grpc-ecosystem/go-grpc-prometheus) - Prometheus client-side and server-side monitoring middleware
68   * [`opentracing`](interceptors/tracing) - [OpenTracing](http://opentracing.io/) client-side and server-side interceptors with support for streaming and handler-returned tags
69
70#### Client
71   * [`retry`](interceptors/retry) - a generic gRPC response code retry mechanism, client-side middleware
72
73#### Server
74   * [`validator`](interceptors/validator) - codegen inbound message validation from `.proto` options
75   * [`recovery`](interceptors/recovery) - turn panics into gRPC errors
76   * [`ratelimit`](interceptors/ratelimit) - grpc rate limiting by your own limiter
77
78
79## Status
80
81This code has been running in *production* since May 2016 as the basis of the gRPC micro services stack at [Improbable](https://improbable.io).
82
83Additional tooling will be added, and contributions are welcome.
84
85## License
86
87`go-grpc-middleware` is released under the Apache 2.0 license. See the [LICENSE](LICENSE) file for details.
88