clientv3: ensure 'DialKeepAliveTime' respects server policy

Signed-off-by: Gyu-Ho Lee <[email protected]>

clientv3/client.go

@@ -25,6 +25,7 @@ import (
 	"sync"
 	"time"
 
+	kp "github.com/coreos/etcd/etcdserver/api/v3rpc/keepalive"
 	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
 
 	"golang.org/x/net/context"
@@ -217,6 +218,10 @@ func (c *Client) dialSetupOpts(endpoint string, dopts ...grpc.DialOption) (opts
 		opts = []grpc.DialOption{grpc.WithTimeout(c.cfg.DialTimeout)}
 	}
 	if c.cfg.DialKeepAliveTime > 0 {
+		// prevent incompatible settings that can lead to connection close from server-side
+		if c.cfg.DialKeepAliveTime < kp.ServerPolicy.MinTime {
+			panic(fmt.Errorf("client keepalive can send too_many_pings (expects >%v, got %v)", kp.ServerPolicy.MinTime, c.cfg.DialKeepAliveTime))
+		}
 		params := keepalive.ClientParameters{
 			Time: c.cfg.DialKeepAliveTime,
 		}