Make secret volume plugin idempotent

pkg/volume/util/util.go

@@ -0,0 +1,62 @@
+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"os"
+	"path"
+
+	"github.com/golang/glog"
+)
+
+const readyFileName = "ready"
+
+// IsReady checks for the existence of a regular file
+// called 'ready' in the given directory and returns
+// true if that file exists.
+func IsReady(dir string) bool {
+	readyFile := path.Join(dir, readyFileName)
+	s, err := os.Stat(readyFile)
+	if err != nil {
+		return false
+	}
+
+	if !s.Mode().IsRegular() {
+		glog.Errorf("ready-file is not a file: %s", readyFile)
+		return false
+	}
+
+	return true
+}
+
+// SetReady creates a file called 'ready' in the given
+// directory.  It logs an error if the file cannot be
+// created.
+func SetReady(dir string) {
+	if err := os.MkdirAll(dir, 0750); err != nil && !os.IsExist(err) {
+		glog.Errorf("Can't mkdir %s: %v", dir, err)
+		return
+	}
+
+	readyFile := path.Join(dir, readyFileName)
+	file, err := os.Create(readyFile)
+	if err != nil {
+		glog.Errorf("Can't touch %s: %v", readyFile, err)
+		return
+	}
+	file.Close()
+}