auth: use NewIncomingContext for "WithRoot"

"WithRoot" is only used within local node, and
"AuthInfoFromCtx" expects token from incoming context.
Embed token with "NewIncomingContext" so that token
can be found in "AuthInfoFromCtx".

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

auth/store.go

@@ -1090,7 +1090,9 @@ func (as *authStore) WithRoot(ctx context.Context) context.Context {
 		"token": token,
 	}
 	tokenMD := metadata.New(mdMap)
-	return metadata.NewOutgoingContext(ctx, tokenMD)
+
+	// use "mdIncomingKey{}" since it's called from local etcdserver
+	return metadata.NewIncomingContext(ctx, tokenMD)
 }
 
 func (as *authStore) HasRole(user, role string) bool {

auth/store_test.go

@@ -701,3 +701,34 @@ func TestRolesOrder(t *testing.T) {
 		}
 	}
 }
+
+// TestAuthInfoFromCtxWithRoot ensures "WithRoot" properly embeds token in the context.
+func TestAuthInfoFromCtxWithRoot(t *testing.T) {
+	b, tPath := backend.NewDefaultTmpBackend()
+	defer os.Remove(tPath)
+
+	tp, err := NewTokenProvider("simple", dummyIndexWaiter)
+	if err != nil {
+		t.Fatal(err)
+	}
+	as := NewAuthStore(b, tp)
+	defer as.Close()
+
+	if err = enableAuthAndCreateRoot(as); err != nil {
+		t.Fatal(err)
+	}
+
+	ctx := context.Background()
+	ctx = as.WithRoot(ctx)
+
+	ai, aerr := as.AuthInfoFromCtx(ctx)
+	if aerr != nil {
+		t.Fatal(err)
+	}
+	if ai == nil {
+		t.Fatal("expected non-nil *AuthInfo")
+	}
+	if ai.Username != "root" {
+		t.Fatalf("expected user name 'root', got %+v", ai)
+	}
+}