Implement SDK SetLabel and SetAnnotation functionality

This implements new functions in the SDK:

- SetLabel(key, value) - that lets you set a label on the backing `GameServer`
- SetAnnotation(key, value) - that lets you set an annotation on the backing
`GameServer`

All keys are prefixed with "stable.agones.dev/sdk-" to maintain isolation.

Closes googleforgames#279

pkg/gameservers/localsdk.go

@@ -18,6 +18,7 @@ import (
 	"io"
 	"sync"
 	"time"
+	"sync"
 
 	"agones.dev/agones/pkg/apis/stable/v1alpha1"
 	"agones.dev/agones/pkg/sdk"

pkg/gameservers/localsdk_test.go

@@ -161,6 +161,60 @@ func TestLocalSDKServerSetAnnotation(t *testing.T) {
 	}
 }
 
+func TestLocalSDKServerSetLabel(t *testing.T) {
+	ctx := context.Background()
+	e := &sdk.Empty{}
+	l := NewLocalSDKServer()
+	kv := &sdk.KeyValue{Key: "foo", Value: "bar"}
+
+	stream := newGameServerMockStream()
+	go func() {
+		err := l.WatchGameServer(e, stream)
+		assert.Nil(t, err)
+	}()
+
+	_, err := l.SetLabel(ctx, kv)
+	assert.Nil(t, err)
+
+	gs, err := l.GetGameServer(ctx, e)
+	assert.Nil(t, err)
+	assert.Equal(t, gs.ObjectMeta.Labels[metadataPrefix+"foo"], "bar")
+
+	select {
+	case msg := <-stream.msgs:
+		assert.Equal(t, msg.ObjectMeta.Labels[metadataPrefix+"foo"], "bar")
+	case <-time.After(2 * l.watchPeriod):
+		assert.FailNow(t, "timeout on receiving messages")
+	}
+}
+
+func TestLocalSDKServerSetAnnotation(t *testing.T) {
+	ctx := context.Background()
+	e := &sdk.Empty{}
+	l := NewLocalSDKServer()
+	kv := &sdk.KeyValue{Key: "bar", Value: "foo"}
+
+	stream := newGameServerMockStream()
+	go func() {
+		err := l.WatchGameServer(e, stream)
+		assert.Nil(t, err)
+	}()
+
+	_, err := l.SetAnnotation(ctx, kv)
+	assert.Nil(t, err)
+
+	gs, err := l.GetGameServer(ctx, e)
+	assert.Nil(t, err)
+	assert.Equal(t, gs.ObjectMeta.Annotations[metadataPrefix+"bar"], "foo")
+
+	select {
+	case msg := <-stream.msgs:
+		assert.Equal(t, msg.ObjectMeta.Annotations[metadataPrefix+"bar"], "foo")
+	case <-time.After(2 * l.watchPeriod):
+		assert.FailNow(t, "timeout on receiving messages")
+	}
+}
+
 func TestLocalSDKServerWatchGameServer(t *testing.T) {
 	t.Parallel()
 

sdks/go/sdk.go

@@ -144,12 +144,11 @@ func (s *SDK) WatchGameServer(f GameServerCallback) error {
 			var gs *sdk.GameServer
 			gs, err = stream.Recv()
 			if err != nil {
-				if err != io.EOF {
-					fmt.Printf("error watching GameServer: %s\n", err.Error())
-				} else {
+				if err == io.EOF {
 					fmt.Println("gameserver event stream EOF received")
 					return
 				}
+				fmt.Printf("error watching GameServer: %s\n", err.Error())
 				// This is to wait for the reconnection, and not peg the CPU at 100%
 				time.Sleep(time.Second)
 				continue