viper作为配置框架，其功能非常的强大，我们没有理由不去了解一下。我们先看官网对它的功能简介：

viper是完整配置解决方案，他可以处理所有类型和格式的配置文件，他有如下功能：

• 设置默认配置
• 支持读取 JSON TOML YAML HCL 和 Java 属性配置文件
• 监听配置文件变化，实时读取读取配置文件内容
• 读取环境变量值
• 读取远程配置系统 (etcd Consul) 和监控配置变化
• 读取命令 Flag 值
• 读取 buffer 值
• 读取确切值

乍一看，未免有相见恨晚之感，可仔细一想，不免脑袋里有另外一种声音：不会不支持读取zookeeper吧？好吧，至少我是这样的。

基于这种想法，当然要去立马尝试，如下：

viper.AddRemoteProvider("zookeeper", "xx.xx.xx.xx:2181", "/viper/test")复制代码

返回结果是：

Unsupported Remote Provider Type zookeeper复制代码

果不其然，于是追踪viper.AddRemoteProvider的源码，发现viper只支持如下几种

var SupportedRemoteProviders = []string{"etcd", "consul", "firestore"}复制代码

如果就此打住，未免有点太可惜，作为偏执狂，总想着能否来改造下viper，让其支持zookeeper，于是在issue上找是否有人遇到同样的问题，还整让我找到了，传送。但是不完整，且稍微有点bug。所以根据他的基础上，我做了些调整。进入正题，我们开始修改viper源码。说明下，我的viper版本是最新的1.7.0

修改源码

1、添加zookeeper.go

添加的位置：github.com/bketelsen/crypt/zookeeper, zookeeper目录需要自己创建，github.com/bketelsen/crypt是viper的依赖包，会自动下载

文件内容：

package zookeeperimport ("errors""fmt"zk "github.com/samuel/go-zookeeper/zk"//"github.com/xordataexchange/crypt/backend""github.com/bketelsen/crypt/backend""strings""time")type Client struct {client    *zk.ConnwaitIndex uint64}func New(machines []string) (*Client, error) {zkclient, _, err := zk.Connect(machines, time.Second)if err != nil {return nil, err}return &Client{zkclient, 0}, nil}func (c *Client) Get(key string) ([]byte, error) {resp, _, err := c.client.Get(key)if err != nil {return nil, err}return []byte(resp), nil}func nodeWalk(prefix string, c *Client, vars map[string]string) error {l, stat, err := c.client.Children(prefix)if err != nil {return err}if stat.NumChildren == 0 {b, _, err := c.client.Get(prefix)if err != nil {return err}vars[prefix] = string(b)} else {for _, key := range l {s := prefix + "/" + key_, stat, err := c.client.Exists(s)if err != nil {return err}if stat.NumChildren == 0 {b, _, err := c.client.Get(s)if err != nil {return err}vars[s] = string(b)} else {nodeWalk(s, c, vars)}}}return nil}func (c *Client) GetValues(key string, keys []string) (map[string]string, error) {vars := make(map[string]string)for _, v := range keys {v = fmt.Sprintf("%s/%s", key, v)v = strings.Replace(v, "/*", "", -1)_, _, err := c.client.Exists(v)if err != nil {return vars, err}if v == "/" {v = ""}err = nodeWalk(v, c, vars)if err != nil {return vars, err}}return vars, nil}func (c *Client) List(key string) (backend.KVPairs, error) {var list backend.KVPairsresp, stat, err := c.client.Children(key)if err != nil {return nil, err}if stat.NumChildren == 0 {return list, nil}entries, err := c.GetValues(key, resp)if err != nil {return nil, err}for k, v := range entries {list = append(list, &backend.KVPair{Key: k, Value: []byte(v)})}return list, nil}func (c *Client) createParents(key string) error {flags := int32(0)acl := zk.WorldACL(zk.PermAll)if key[0] != '/' {return errors.New("Invalid path")}payload := []byte("")pathString := ""pathNodes := strings.Split(key, "/")for i := 1; i < len(pathNodes); i++ {pathString += "/" + pathNodes[i]_, err := c.client.Create(pathString, payload, flags, acl)// not being able to create the node because it exists or not having// sufficient rights is not an issue. It is ok for the node to already// exist and/or us to only have read rightsif err != nil && err != zk.ErrNodeExists && err != zk.ErrNoAuth {return err}}return nil}func (c *Client) Set(key string, value []byte) error {err := c.createParents(key)if err != nil {return err}_, err = c.client.Set(key, []byte(value), -1)return err}func (c *Client) Watch(key string, stop chan bool) <-chan *backend.Response {respChan := make(chan *backend.Response, 0)go func() {for {resp, _, watch, err := c.client.GetW(key)if err != nil {respChan <- &backend.Response{nil, err}time.Sleep(time.Second * 5)}select {case e := <-watch:if e.Type == zk.EventNodeDataChanged {resp, _, err = c.client.Get(key)if err != nil {respChan <- &backend.Response{nil, err}}c.waitIndex = 0respChan <- &backend.Response{[]byte(resp), nil}}}}}()return respChan}复制代码

这个文件是实现ConfigManager接口，我们在上图中看到etcd，consul，filestore，均有实现该接口，接口的定义很简单

type ConfigManager interface {Get(key string) ([]byte, error)List(key string) (KVPairs, error)Set(key string, value []byte) errorWatch(key string, stop chan bool) <-chan *Response}复制代码

2、修改config.go

文件的位置：github.com/bketelsen/crypt/config/config.go，如下图

• 在 func NewStandardEtcdConfigManager(machines []string) (ConfigManager, error) 方法下面添加如下方法：

// NewStandardZookeeperConfigManager returns a new ConfigManager backed by Zookeeper.// Data will be encrypted.func NewStandardZookeeperConfigManager(machines []string) (ConfigManager, error) {store, err := zookeeper.New(machines)if err != nil {return nil, err}return NewStandardConfigManager(store)}复制代码

• 在 func NewEtcdConfigManager(machines []string, keystore io.Reader) (ConfigManager, error)方法下面添加如下方法：

// NewZookeeperConfigManager returns a new ConfigManager backed by zookeeper.// Data will be encrypted.func NewZookeeperConfigManager(machines []string, keystore io.Reader) (ConfigManager, error) {store, err := zookeeper.New(machines)if err != nil {return nil, err}return NewConfigManager(store, keystore)}复制代码

这两个方法是初始化ConfigManager对象，也就是我们刚才添加的zookeeper.go文件的对象

3、修改remote.go

文件的位置：github.com/spf13/viper/remote/remote.go,如下图

找到74行，用下面的代码替换func getConfigManager(rp viper.RemoteProvider) (crypt.ConfigManager, error)方法

func getConfigManager(rp viper.RemoteProvider) (crypt.ConfigManager, error) {var cm crypt.ConfigManagervar err errorif rp.SecretKeyring() != "" {var kr *os.Filekr, err = os.Open(rp.SecretKeyring())if err != nil {return nil, err}defer kr.Close()switch rp.Provider() {case "etcd":cm, err = crypt.NewEtcdConfigManager([]string{rp.Endpoint()}, kr)case "zookeeper":cm, err = crypt.NewZookeeperConfigManager([]string{rp.Endpoint()}, kr)case "firestore":cm, err = crypt.NewFirestoreConfigManager([]string{rp.Endpoint()}, kr)default:cm, err = crypt.NewConsulConfigManager([]string{rp.Endpoint()}, kr)}} else {switch rp.Provider() {case "etcd":cm, err = crypt.NewStandardEtcdConfigManager([]string{rp.Endpoint()})case "zookeeper":cm, err = crypt.NewStandardZookeeperConfigManager([]string{rp.Endpoint()})case "firestore":cm, err = crypt.NewStandardFirestoreConfigManager([]string{rp.Endpoint()})default:cm, err = crypt.NewStandardConsulConfigManager([]string{rp.Endpoint()})}}if err != nil {return nil, err}return cm, nil}复制代码

细心的读者可能已经发现，其实就添加了两个case选项：

4、修改viper.go

文件的位置：github.com/spf13/viper/viper.go,如下图

取+监听zookeeper(1)\image-20200521222843002.png)

找到两个SupportedRemoteProviders定义的定法，1.7.0版本的行号分别是：290，331。只要添加 zookeeper,即可

SupportedRemoteProviders = []string{"etcd", "consul", "firestore", "zookeeper"}复制代码

好了，修改代码的工作已经完了，接下来我们来测试：

测试

注意：zookeeper中已经设置了内容

set /viper/test {"appName":"test","nodes":["127.0.0.1","127.0.0.2","127.0.0.3"]}

package mainimport ("fmt""github.com/fsnotify/fsnotify""github.com/spf13/viper"_ "github.com/spf13/viper/remote""time")type config struct {AppName stringNodes   []string}func main() {var waitGroup=sync.WaitGroup{}waitGroup.Add(1)readRemoteZookeeper()go watchRemoteZookeeper()waitGroup.Wait()}func readRemoteZookeeper() {viper.AddRemoteProvider("zookeeper", "62.234.15.24:2181", "/viper/test")viper.SetConfigType("json") err := viper.ReadRemoteConfig()if err != nil {panic(fmt.Sprintf("read remote zookeeper error:+%v", err))}var C configviper.Unmarshal(&C)fmt.Printf("从zookeeper读取配置内容:%+v\n", C)}func watchRemoteZookeeper() {go func() {for {            //delay after each requesttime.Sleep(time.Second * 5)err := viper.WatchRemoteConfig()if err != nil {fmt.Errorf("unable to read remote config: %v", err)continue}fmt.Printf("从zookeeper读取更新内容:appName=%s,nodes=%+v\n", viper.Get("appName"), viper.Get("nodes"))}}()}复制代码

输出内容：

从zookeeper读取配置内容:{AppName:test Nodes:[127.0.0.1 127.0.0.2 127.0.0.3]}从zookeeper读取更新内容:appName=test,nodes=[127.0.0.1 127.0.0.2 127.0.0.3]复制代码

如果我们修改zookeeper的内容，则viper会读取到更新后的内容：

set /viper/test {"appName":"test","nodes":["127.0.0.1","127.0.0.2","127.0.0.3","127.0.0.4"]}

从zookeeper读取更新内容:appName=test,nodes=[127.0.0.1 127.0.0.2 127.0.0.3 127.0.0.4]复制代码

结语

让viper支持zookeeper并不复杂的，并且基本上不需要修改原有的方法， 这要归结于viper用到一个非常重要的设计原则：开闭原则，读者可以自行体会。

关于viper的基本使用，github已经有非常详细的例子，这里就不再赘述，如有疑问，可以私信我

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