Do not touch grpc logger from within the packages

Libraries should not make process wide changes unless requested to.

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

cmd/ctr/main.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
+	"log"
 	"os"
 
 	"github.com/containerd/containerd/namespaces"
@@ -9,11 +11,15 @@ import (
 	"github.com/containerd/containerd/version"
 	"github.com/sirupsen/logrus"
 	"github.com/urfave/cli"
+	"google.golang.org/grpc/grpclog"
 )
 
 var extraCmds = []cli.Command{}
 
 func init() {
+	// Discard grpc logs so that they don't mess with our stdio
+	grpclog.SetLogger(log.New(ioutil.Discard, "", log.LstdFlags))
+
 	cli.VersionPrinter = func(c *cli.Context) {
 		fmt.Println(c.App.Name, version.Package, c.App.Version)
 	}