gRPC-Go

TheGoimplementation ofgRPC:A high performance, open source, general RPC framework that puts mobile and HTTP/2 first. For more information see the Go gRPC docs,or jump directly into thequick start.

Prerequisites

• Go:any one of thetwo latest majorreleases.

Installation

Simply add the following import to your code, and thengo [build|run|test] will automatically fetch the necessary dependencies:

import"google.golang.org/grpc"

Note:If you are trying to accessgrpc-gofromChina,see the FAQbelow.

Learn more

• Go gRPC docs,which include aquick startandAPI referenceamong other resources
• Low-level technical docsfrom this repository
• Performance benchmark
• Examples

FAQ

I/O Timeout Errors

Thegolang.orgdomain may be blocked from some countries.go getusually 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.

• With Go module support: it is possible to use thereplacefeature ofgo modto 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. For details, refer togolang/go issue #28652.

Compiling error, undefined: grpc.SupportPackageIsVersion

Please update to the latest version of gRPC-Go using go get google.golang.org/grpc.

How to turn on logging

The default logger is controlled by environment variables. Turn everything on like this:

$exportGRPC_GO_LOG_VERBOSITY_LEVEL=99
$exportGRPC_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 totrigger 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 onboth client and server,and see if there are any transport errors.