viper配置框架的介紹支援zookeeper的讀取和監聽
viper作為配置框架，其功能非常的強大，我們沒有理由不去了解一下。我們先看官網對它的功能簡介：
viper是完整配置解決方案，他可以處理所有型別和格式的配置檔案，他有如下功能：
- 設定預設配置
- 支援讀取 JSON TOML YAML HCL 和 Java 屬性配置檔案
- 監聽配置檔案變化，實時讀取讀取配置檔案內容
- 讀取環境變數值
- 讀取遠端配置系統 (etcd Consul) 和監控配置變化
- 讀取命令 Flag 值
- 讀取 buffer 值
- 讀取確切值
乍一看，未免有相見恨晚之感，可仔細一想，不免腦袋裡有另外一種聲音：不會不支援讀取 zookeeper 吧？好吧，至少我是這樣的。
基於這種想法，當然要去立馬嘗試，如下：
viper.AddRemoteProvider("zookeeper","xx.xx.xx.xx:2181","/viper/test")
返回結果是：
Unsupported Remote Provider Type zookeeper
果不其然，於是追蹤 viper.AddRemoteProvider 的原始碼，發現viper只支援如下幾種
var SupportedRemoteProviders = []string{"etcd","consul","firestore"}
如果就此打住，未免有點太可惜，作為偏執狂，總想著能否來改造下viper，讓其支援 zookeeper
1.7.0
修改原始碼
1、新增zookeeper.go
新增的位置： github.com/bketelsen/crypt/zookeeper,zookeeper 目錄需要自己建立， github.com/bketelsen/crypt 是viper的依賴包，會自動下載
檔案內容：
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
_,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,vars)
if err != nil {
return vars,err
}
}
return vars,nil
}
func (c *Client) List(key string) (backend.KVPairs,error) {
var list backend.KVPairs
resp,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
}這個檔案是實現 ConfigManager 介面，我們在上圖中看到 etcd ， consul ， filestore ，均有實現該介面，介面的定義很簡單
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
檔案的位置： github.com/bketelsen/crypt/config/config.go ，如下圖
在 func NewStandardEtcdConfigManager(machines []string) (ConfigManager,error) 方法下面新增如下方法：
// 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) 方法下面新增如下方法：
// NewZookeeperConfigManager returns a new ConfigManager backed by zookeeper. // Data will be encrypted. func NewZookeeperConfigManager(machines []string,err } return NewConfigManager(store,keystore) }
這兩個方法是初始化 ConfigManager 物件，也就是我們剛才新增的 zookeeper.go 檔案的物件
3、修改remote.go
檔案的位置： github.com/spf13/viper/remote/remote.go,如下圖
找到74行，用下面的程式碼替換 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
}
細心的讀者可能已經發現，其實就添加了兩個case選項：
4、修改viper.go
檔案的位置： github.com/spf13/viper/viper.go,如下圖
取+監聽zookeeper(1)\image-20200521222843002.png)
找到兩個 SupportedRemoteProviders 定義的定法，1.7.0版本的行號分別是：290，331。只要新增 zookeeper,即可
SupportedRemoteProviders = []string{"etcd","firestore","zookeeper"}
好了，修改程式碼的工作已經完了，接下來我們來測試：
測試
注意：zookeeper中已經設定了內容
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("從zookeeper讀取配置內容:%+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("從zookeeper讀取更新內容:appName=%s,nodes=%+v\n",viper.Get("appName"),viper.Get("nodes"))
}
}()
}
輸出內容：
從zookeeper讀取配置內容:{AppName:test Nodes:[127.0.0.1 127.0.0.2 127.0.0.3]}
從zookeeper讀取更新內容:appName=test,nodes=[127.0.0.1 127.0.0.2 127.0.0.3]
如果我們修改zookeeper的內容，則viper會讀取到更新後的內容：
set /viper/test {"appName":"test","127.0.0.3","127.0.0.4"]}
從zookeeper讀取更新內容:appName=test,nodes=[127.0.0.1 127.0.0.2 127.0.0.3 127.0.0.4]
結語
讓viper支援 zookeeper 並不複雜的，並且基本上不需要修改原有的方法， 這要歸結於viper用到一個非常重要的設計原則： 開閉原則 ，讀者可以自行體會。
關於viper的基本使用， github 已經有非常詳細的例子，這裡就不再贅述，如有疑問，可以私信我
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