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
Go gRPC docs, or jump directly into the quick start.
Prerequisites
Installation
Simply add the following import to your code, and then go [build|run|test]
will automatically fetch the necessary dependencies:
import "google.golang.org/grpc"
Note: If you are trying to access grpc-go
from China, see the
FAQ below.
Learn more
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.
-
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. For details, refer to golang/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:
$ export GRPC_GO_LOG_VERBOSITY_LEVEL=99
$ export 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:
- mis-configured transport credentials, connection failed on handshaking
- bytes disrupted, possibly by a proxy in between
- server shutdown
- 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.