Delimma隐
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
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"}
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， 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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