142 lines
4.7 KiB
Markdown
142 lines
4.7 KiB
Markdown
# gRPC-Go
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[](https://travis-ci.org/grpc/grpc-go)
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[][API]
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[](https://goreportcard.com/report/github.com/grpc/grpc-go)
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The [Go][] implementation of [gRPC][]: A high performance, open source, general
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RPC framework that puts mobile and HTTP/2 first. For more information see the
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[Go gRPC docs][], or jump directly into the [quick start][].
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## Prerequisites
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- **[Go][]**: any one of the **three latest major** [releases][go-releases].
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## Installation
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With [Go module][] support (Go 1.11+), simply add the following import
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```go
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import "google.golang.org/grpc"
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```
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to your code, and then `go [build|run|test]` will automatically fetch the
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necessary dependencies.
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Otherwise, to install the `grpc-go` package, run the following command:
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```console
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$ go get -u google.golang.org/grpc
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```
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> **Note:** If you are trying to access `grpc-go` from **China**, see the
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> [FAQ](#FAQ) below.
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## Learn more
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- [Go gRPC docs][], which include a [quick start][] and [API
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reference][API] among other resources
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- [Low-level technical docs](Documentation) from this repository
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- [Performance benchmark][]
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- [Examples](examples)
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## FAQ
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### I/O Timeout Errors
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The `golang.org` domain may be blocked from some countries. `go get` usually
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produces an error like the following when this happens:
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```console
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$ go get -u google.golang.org/grpc
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package google.golang.org/grpc: unrecognized import path "google.golang.org/grpc" (https fetch: Get https://google.golang.org/grpc?go-get=1: dial tcp 216.239.37.1:443: i/o timeout)
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```
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To build Go code, there are several options:
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- Set up a VPN and access google.golang.org through that.
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- Without Go module support: `git clone` the repo manually:
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```sh
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git clone https://github.com/grpc/grpc-go.git $GOPATH/src/google.golang.org/grpc
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```
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You will need to do the same for all of grpc's dependencies in `golang.org`,
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e.g. `golang.org/x/net`.
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- With Go module support: it is possible to use the `replace` feature of `go
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mod` to create aliases for golang.org packages. In your project's directory:
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```sh
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go mod edit -replace=google.golang.org/grpc=github.com/grpc/grpc-go@latest
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go mod tidy
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go mod vendor
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go build -mod=vendor
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```
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Again, this will need to be done for all transitive dependencies hosted on
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golang.org as well. For details, refer to [golang/go issue #28652](https://github.com/golang/go/issues/28652).
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### Compiling error, undefined: grpc.SupportPackageIsVersion
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#### If you are using Go modules:
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Ensure your gRPC-Go version is `require`d at the appropriate version in
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the same module containing the generated `.pb.go` files. For example,
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`SupportPackageIsVersion6` needs `v1.27.0`, so in your `go.mod` file:
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```go
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module <your module name>
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require (
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google.golang.org/grpc v1.27.0
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)
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```
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#### If you are *not* using Go modules:
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Update the `proto` package, gRPC package, and rebuild the `.proto` files:
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```sh
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go get -u github.com/golang/protobuf/{proto,protoc-gen-go}
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go get -u google.golang.org/grpc
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protoc --go_out=plugins=grpc:. *.proto
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```
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### How to turn on logging
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The default logger is controlled by environment variables. Turn everything on
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like this:
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```console
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$ export GRPC_GO_LOG_VERBOSITY_LEVEL=99
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$ export GRPC_GO_LOG_SEVERITY_LEVEL=info
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```
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### The RPC failed with error `"code = Unavailable desc = transport is closing"`
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This error means the connection the RPC is using was closed, and there are many
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possible reasons, including:
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1. mis-configured transport credentials, connection failed on handshaking
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1. bytes disrupted, possibly by a proxy in between
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1. server shutdown
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1. Keepalive parameters caused connection shutdown, for example if you have configured
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your server to terminate connections regularly to [trigger DNS lookups](https://github.com/grpc/grpc-go/issues/3170#issuecomment-552517779).
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If this is the case, you may want to increase your [MaxConnectionAgeGrace](https://pkg.go.dev/google.golang.org/grpc/keepalive?tab=doc#ServerParameters),
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to allow longer RPC calls to finish.
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It can be tricky to debug this because the error happens on the client side but
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the root cause of the connection being closed is on the server side. Turn on
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logging on __both client and server__, and see if there are any transport
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errors.
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[API]: https://pkg.go.dev/google.golang.org/grpc
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[Go]: https://golang.org
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[Go module]: https://github.com/golang/go/wiki/Modules
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[gRPC]: https://grpc.io
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[Go gRPC docs]: https://grpc.io/docs/languages/go
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[Performance benchmark]: https://performance-dot-grpc-testing.appspot.com/explore?dashboard=5180705743044608
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[quick start]: https://grpc.io/docs/languages/go/quickstart
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[go-releases]: https://golang.org/doc/devel/release.html
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