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")
返回结果是：
Unsupported Remote Provider Type zookeeper
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"}
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 zookeeper
import (
"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.Conn
waitIndex 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.KVPairs
resp, 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 rights
if 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 = 0
respChan <- &backend.Response{[]byte(resp), nil}
}
}
}
}()
return respChan
}
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) error
Watch(key string, stop chan bool) <-chan *Response
}
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)
}
- 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)
}
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.ConfigManager
var err error
if rp.SecretKeyring() != "" {
var kr *os.File
kr, 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
}
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
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"}
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 main
import (
"fmt"
"github.com/fsnotify/fsnotify"
"github.com/spf13/viper"
_ "github.com/spf13/viper/remote"
"time"
)
type config struct {
AppName string
Nodes []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 config
viper.Unmarshal(&C)
fmt.Printf("从zookeeper读取配置内容:%+v\n", C)
}
func watchRemoteZookeeper() {
go func() {
for {
//delay after each request
time.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"))
}
}()
}
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]
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]
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
