storage.go

/*
Copyright 2015 Gravitational, Inc.

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 utils

import (
	"encoding/json"
	"io/ioutil"

	log "github.com/Sirupsen/logrus"
	"github.com/gravitational/trace"
)

// AddrStorage is used to store information locally for
// every client that connects in the cluster, so it can always have
// up-to-date info about auth servers
type AddrStorage interface {
	// SetAddresses saves addresses
	SetAddresses([]NetAddr) error
	// GetAddresses
	GetAddresses() ([]NetAddr, error)
}

// FileAddrStorage is a file based address storage
type FileAddrStorage struct {
	filePath string
}

// SetAddresses updates storage with new address list
func (fs *FileAddrStorage) SetAddresses(addrs []NetAddr) error {
	bytes, err := json.Marshal(addrs)
	if err != nil {
		return trace.Wrap(err)
	}
	err = ioutil.WriteFile(fs.filePath, bytes, 0666)
	if err != nil {
		log.Error(err)
		return trace.ConvertSystemError(err)
	}
	return nil
}

// GetAddresses returns saved address list
func (fs *FileAddrStorage) GetAddresses() ([]NetAddr, error) {
	bytes, err := ioutil.ReadFile(fs.filePath)
	if err != nil {
		return nil, trace.ConvertSystemError(err)
	}
	var addrs []NetAddr
	if len(bytes) > 0 {
		err = json.Unmarshal(bytes, &addrs)
		if err != nil {
			return nil, trace.Wrap(err)
		}
	}
	return addrs, nil
}

// NewFileAddrStorage returns new instance of file-based address storage
func NewFileAddrStorage(filePath string) *FileAddrStorage {
	return &FileAddrStorage{
		filePath: filePath,
	}
}