gRPC-Go

The Go implementation of gRPC: A high performance, open source, general RPC framework that puts mobile and HTTP/2 first. For more information see the gRPC Quick Start: Go guide.

Installation

To install this package, you need to install Go and setup your Go workspace on your computer. The simplest way to install the library is to run:

$ go get -u google.golang.org/grpc

With Go module support (Go 1.11+), simply import "google.golang.org/grpc" in your source code and go [build|run|test] will automatically download the necessary dependencies (Go modules ref).

If you are trying to access grpc-go from within China, please see the FAQ below.

Prerequisites

gRPC-Go officially supports the three latest major releases of Go.

Documentation

• See godoc for package and API descriptions.
• Documentation on specific topics can be found in the Documentation directory.
• Examples can be found in the examples directory.

Performance

Performance benchmark data for grpc-go and other languages is maintained in this dashboard.

Status

General Availability Google Cloud Platform Launch Stages.

FAQ

I/O Timeout Errors

The golang.org domain may be blocked from some countries. go get usually produces an error like the following when this happens:

$ go get -u google.golang.org/grpc
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)

To build Go code, there are several options:

• Set up a VPN and access google.golang.org through that.

• Without Go module support: git clone the repo manually:

  git clone https://github.com/grpc/grpc-go.git $GOPATH/src/google.golang.org/grpc
  

  You will need to do the same for all of grpc's dependencies in golang.org, e.g. golang.org/x/net.

• With Go module support: it is possible to use the replace feature of go mod to create aliases for golang.org packages. In your project's directory:

  go mod edit -replace=google.golang.org/grpc=github.com/grpc/grpc-go@latest
  go mod tidy
  go mod vendor
  go build -mod=vendor
  

  Again, this will need to be done for all transitive dependencies hosted on golang.org as well. Please refer to this issue in the golang repo regarding this concern.

Compiling error, undefined: grpc.SupportPackageIsVersion

If you are using Go modules:

Please ensure your gRPC-Go version is required at the appropriate version in the same module containing the generated .pb.go files. For example, SupportPackageIsVersion6 needs v1.27.0, so in your go.mod file:

module <your module name>

require (
    google.golang.org/grpc v1.27.0
)

If you are not using Go modules:

Please update proto package, gRPC package and rebuild the proto files:

• go get -u github.com/golang/protobuf/{proto,protoc-gen-go}
• go get -u google.golang.org/grpc
• protoc --go_out=plugins=grpc:. *.proto

How to turn on logging

The default logger is controlled by the environment variables. Turn everything on by setting:

GRPC_GO_LOG_VERBOSITY_LEVEL=99 GRPC_GO_LOG_SEVERITY_LEVEL=info

The RPC failed with error "code = Unavailable desc = transport is closing"

This error means the connection the RPC is using was closed, and there are many possible reasons, including:

1. mis-configured transport credentials, connection failed on handshaking
2. bytes disrupted, possibly by a proxy in between
3. server shutdown
4. Keepalive parameters caused connection shutdown, for example if you have configured your server to terminate connections regularly to trigger DNS lookups. If this is the case, you may want to increase your MaxConnectionAgeGrace, to allow longer RPC calls to finish.

It can be tricky to debug this because the error happens on the client side but the root cause of the connection being closed is on the server side. Turn on logging on both client and server, and see if there are any transport errors.