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除了上次的warden直连方式外,kratos有另一个服务发现sdk : discovery
discovery 可以先简单理解为一个http服务、
它最简单的发现过程可能是这样的:
1、service 向discovery 服务注册 appid
2、client 通过 appid 从discovery 查询 service 的addr
当然 远不止这么简单,还包含了很多功能在里面的,例如服务自发现、负载均衡等
本节仅先看个最简单的服务发现的demo
首先走一遍discovery的http的api
// innerRouter init local router api path.
func innerRouter(e *bm.Engine) {
group := e.Group("/discovery")
{
group.POST("/register", register)
group.POST("/renew", renew)
group.POST("/cancel", cancel)
group.GET("/fetch/all", initProtect, fetchAll)
group.GET("/fetch", initProtect, fetch)
group.GET("/fetchs", initProtect, fetchs)
group.GET("/poll", initProtect, poll)
group.GET("/polls", initProtect, polls)
//manager
group.POST("/set", set)
group.GET("/nodes", initProtect, nodes)
}
}
discovery里面的bm引擎注册了这些接口, 接着我用postman 测了测。
POST http://HOST/discovery/renew
curl 'http://127.0.0.1:7171/discovery/renew' -d "zone=sh1&env=test&appid=provider&hostname=myhostname"
*****成功*****
{
"code":0,
"message":""
}
****失败****
{
"code":-400,
"message":"-400"
}
POST http://HOST/discovery/cancel
curl 'http://127.0.0.1:7171/discovery/cancel' -d "zone=sh1&env=test&appid=provider&hostname=myhostname"
*****成功*****
{
"code":0,
"message":""
}
****失败****
{
"code":-400,
"message":"-400"
}
官方应用发现实现逻辑
选择可用的节点,将应用appid加入poll的appid列表
如果polls请求返回err,则切换node节点,切换逻辑与自发现错误时切换逻辑一致
如果polls返回-304 ,说明appid无变更,重新发起poll监听变更
polls接口返回appid的instances列表,完成服务发现,根据需要选择不同的负载均衡算法进行节点的调度
直接new一个new服务然后将demo服务注册到discovery
主函数里面服务注册部分添加类似下面注册代码。
ip := "127.0.0.1"
port := "9000"
hn, _ := os.Hostname()
dis := discovery.New(nil)
ins := &naming.Instance{
Zone: env.Zone,
Env: env.DeployEnv,
AppID: "demo.service",
Hostname: hn,
Addrs: []string{
"grpc://" + ip + ":" + port,
},
}
cancel, err := dis.Register(context.Background(), ins)
if err != nil {
panic(err)
}
defer cancel()
panic 找不到节点,这个是我们discovery的节点地址 可以在环境变量里面添加。
I:VSProjectkratos-notekratos-notewardendiscoveryserver>kratos run
INFO 01/04-19:32:28.198 I:/VSProject/go/pkg/mod/github.com/bilibili/kratos@v0.3.2-0.20191224125553-6e1180f53a8e/pkg/net/rpc/warden/server.go:329 warden: start grpc listen addr: [::]:9000
panic: invalid discovery config nodes:[] region:region01 zone:zone01 deployEnv:dev host:DESKTOP-NUEKD5O
配置discovery节点后成功注册
I:VSProjectkratos-notekratos-notewardendiscoveryserver>set DISCOVERY_NODES=127.0.0.1:7171
I:VSProjectkratos-notekratos-notewardendiscoveryserver>kratos run
INFO 01/04-19:40:25.426 I:/VSProject/kratos-note/kratos-note/warden/discovery/server/cmd/main.go:23 abc start
2020/01/04 19:40:25 start watch filepath: I:VSProjectkratos-notekratos-notewardendiscoveryserverconfigs
INFO 01/04-19:40:25.497 I:/VSProject/go/pkg/mod/github.com/bilibili/kratos@v0.3.2-0.20191224125553-6e1180f53a8e/pkg/net/http/blademaster/server.go:98 blademaster: start http listen addr: 0.0.0.0:8000
[warden] config is Deprecated, argument will be ignored. please use -grpc flag or GRPC env to configure warden server.
INFO 01/04-19:40:25.500 I:/VSProject/go/pkg/mod/github.com/bilibili/kratos@v0.3.2-0.20191224125553-6e1180f53a8e/pkg/net/rpc/warden/server.go:329 warden: start grpc listen addr: [::]:9000
INFO 01/04-19:40:25.501 I:/VSProject/go/pkg/mod/github.com/bilibili/kratos@v0.3.2-0.20191224125553-6e1180f53a8e/pkg/naming/discovery/discovery.go:248 disocvery: AddWatch(infra.discovery) already watch(false)
INFO 01/04-19:40:25.514 I:/VSProject/go/pkg/mod/github.com/bilibili/kratos@v0.3.2-0.20191224125553-6e1180f53a8e/pkg/naming/discovery/discovery.go:631 discovery: successfully polls(http://127.0.0.1:7171/discovery/polls?appid=infra.discovery&env=dev&hostname=DESKTOP-NUEKD5O&latest_timestamp=0) instances ({"infra.discovery":{"instances":{"sh001":[{"region":"sh","zone":"sh001","env":"dev","appid":"infra.discovery","hostname":"test1","addrs":["http://127.0.0.1:7171"],"version":"","latest_timestamp":1578122538945305700,"metadata":null,"status":1}]},"latest_timestamp":1578122538945305700,"scheduler":null}})
INFO 01/04-19:40:25.527 I:/VSProject/go/pkg/mod/github.com/bilibili/kratos@v0.3.2-0.20191224125553-6e1180f53a8e/pkg/naming/discovery/discovery.go:414 discovery: register client.Get(http://127.0.0.1:7171/discovery/register) env(dev) appid(demo.service) addrs([grpc://127.0.0.1:9000]) success
现在我们跟着日志走一遍。
如图理解,服务注册逻辑应该是register -> renew ->cancel 注册 然后 不停给心跳 最后取消注册。
截取一条本地服务注册日志
操作大概是:
1、启动discovery服务
2、启动demo.server 注册demo.server appid 服务
3、过一小会等待心跳,关闭demo.server
接着可以看到整个日志的过程大致上是 :
1、 0 : 启动dicovery服务
2、 2/3/4 : 服务初始化
3、 5 : polls 长轮循 infra.discovery 服务自发现
4、 6/7: 新的连接 & 服务注册、这时候我们起动的demo.server服务注册上来了
5、 9 : polls 长轮循 infra.discovery 服务自发现
6、 10 : renew心跳
7、 12 : 最后我杀掉了注册的服务,出现了cancel请求。
从日志看逻辑理解基本上也没有太多偏差,接着看看服务发现。
0:discovery -conf discovery-example.toml -log.v=0
1:
2:INFO 01/10-10:31:19.575 C:/server/src/go/src/discovery/discovery/syncup.go:160 discovery 3:changed nodes:[127.0.0.1:7171] zones:map[]
4:INFO 01/10-10:31:19.575 C:/server/src/go/pkg/mod/github.com/bilibili/kratos@v0.1.0/pkg/net/http/blademaster/server.go:98 blademaster: start http listen addr: 127.0.0.1:7171
INFO 01/10-10:31:19.575 C:/server/src/go/src/discovery/registry/registry.go:219 Polls from(test1) new connection(1)
5:INFO 01/10-10:31:31.796 http-access-log ts=0 method=GET ip=127.0.0.1 traceid= user=no_user params=appid=infra.discovery&env=dev&hostname=DESKTOP-9NFHKD0&latest_timestamp=0 msg=0 stack=<nil> err= timeout_quota=39.98 path=/discovery/polls ret=0
6:INFO 01/10-10:31:31.798 C:/server/src/go/src/discovery/registry/registry.go:219 Polls from(DESKTOP-9NFHKD0) new connection(1)
7:INFO 01/10-10:31:31.799 http-access-log method=POST user=no_user path=/discovery/register err= ts=0 params=addrs=grpc%3A%2F%2F127.0.0.1%3A9000&appid=demo.service&env=dev&hostname=DESKTOP-9NFHKD0&metadata=®ion=region01&status=1&version=&zone=zone01 stack=<nil> ret=0 timeout_quota=39.98 ip=127.0.0.1 msg=0 traceid=
8:INFO 01/10-10:32:01.799 C:/server/src/go/src/discovery/registry/registry.go:370 DelConns from(DESKTOP-9NFHKD0) delete(1)
9:ERROR 01/10-10:32:01.799 http-access-log method=GET ip=127.0.0.1 err=-304 timeout_quota=39.98 user=no_user path=/discovery/polls params=appid=infra.discovery&env=dev&hostname=DESKTOP-9NFHKD0&latest_timestamp=1578623479566211700 ret=-304 msg=-304 stack=-304 ts=30.0011342 traceid=
10:INFO 01/10-10:32:01.799 http-access-log msg=0 err= timeout_quota=39.98 method=POST ip=127.0.0.1 user=no_user ret=0 path=/discovery/renew traceid= params=appid=demo.service&env=dev&hostname=DESKTOP-9NFHKD0®ion=region01&zone=zone01 stack=<nil> ts=0
11:INFO 01/10-10:32:01.800 C:/server/src/go/src/discovery/registry/registry.go:219 Polls from(DESKTOP-9NFHKD0) new connection(1)
12:INFO 01/10-10:32:08.499 http-access-log timeout_quota=39.98 path=/discovery/cancel ret=0 stack=<nil> ip=127.0.0.1 msg=0 traceid= ts=0 method=POST user=no_user err= params=appid=demo.service&env=dev&hostname=DESKTOP-9NFHKD0®ion=region01&zone=zone01
同样先配置discovert节点 set DISCOVERY_NODES=127.0.0.1:7171
NewClient()改成如下方式
package dao
import (
"context"
"github.com/bilibili/kratos/pkg/naming/discovery"
"github.com/bilibili/kratos/pkg/net/rpc/warden"
"github.com/bilibili/kratos/pkg/net/rpc/warden/resolver"
"google.golang.org/grpc"
)
// AppID your appid, ensure unique.
const AppID = "demo.service" // NOTE: example
func init(){
// NOTE: 注意这段代码,表示要使用discovery进行服务发现
// NOTE: 还需注意的是,resolver.Register是全局生效的,所以建议该代码放在进程初始化的时候执行
// NOTE: !!!切记不要在一个进程内进行多个不同中间件的Register!!!
// NOTE: 在启动应用时,可以通过flag(-discovery.nodes) 或者 环境配置(DISCOVERY_NODES)指定discovery节点
resolver.Register(discovery.Builder())
}
// NewClient new member grpc client
func NewClient(cfg *warden.ClientConfig, opts ...grpc.DialOption) (DemoClient, error) {
client := warden.NewClient(cfg, opts...)
conn, err := client.Dial(context.Background(), "discovery://default/"+AppID)
if err != nil {
return nil, err
}
// 注意替换这里:
// NewDemoClient方法是在"api"目录下代码生成的
// 对应proto文件内自定义的service名字,请使用正确方法名替换
return NewDemoClient(conn), nil
}
同时嵌入dao结构里面、和上次warden direct方式一样做SayHello接口测试调用。
// dao dao.
type dao struct {
db *sql.DB
redis *redis.Redis
mc *memcache.Memcache
demoClient demoapi.DemoClient
cache *fanout.Fanout
demoExpire int32
}
// New new a dao and return.
func New(r *redis.Redis, mc *memcache.Memcache, db *sql.DB) (d Dao, err error) {
var cfg struct{
DemoExpire xtime.Duration
}
if err = paladin.Get("application.toml").UnmarshalTOML(&cfg); err != nil {
return
}
grpccfg := &warden.ClientConfig{
Dial: xtime.Duration(time.Second * 10),
Timeout: xtime.Duration(time.Millisecond * 250),
Subset: 50,
KeepAliveInterval: xtime.Duration(time.Second * 60),
KeepAliveTimeout: xtime.Duration(time.Second * 20),
}
//paladin.Get("grpc.toml").UnmarshalTOML(grpccfg)
var grpcClient demoapi.DemoClient
grpcClient, err = NewClient(grpccfg)
d = &dao{
db: db,
redis: r,
mc: mc,
demoClient : grpcClient,
cache: fanout.New("cache"),
demoExpire: int32(time.Duration(cfg.DemoExpire) / time.Second),
}
return
}
操作流程
1、启动discovery服务
2、启动demo.server 注册为 demo.server 服务
3、启动demo.client、
4、最后从demo.client的SayHello http接口 调到demo.server的grpc SayHello 接口。
我发现个别时候调用做服务发现,会发现client起不来, context deadline exceeded。
因为我把new client加在了dao里面,超时的话,demo.client就直接pannic了
根据client日志可以发现
warden client: dial discovery://default/demo.service?subset=50 error context deadline exceeded!panic: context deadline exceeded
client : host:127.0.0.1:7171, url:http://127.0.0.1:7171/discovery/polls?appid=infra.discovery&env=dev&hostname=DESKTOP-9NFHKD0&latest_timestamp=1578902420717217500
在调用discovery polls的时候超时了,我配置的grpc dial 期限为10s, 在官方discovery文档介绍中写到discovery在做服务节点自发现的时候,如果server节点实例没有变更,则接口会阻塞直到30s返回-304。(poll(polls) 接口为长轮训接口)
INFO 01/10-15:22:34.436 http-access-log method=GET path=/discovery/polls user=no_user params=appid=infra.discovery&env=dev&hostname=CLII&latest_timestamp=0 stack=<nil> err= timeout_quota=39.98 ts=0 msg=0 traceid= ip=127.0.0.1 ret=0
INFO 01/10-15:22:34.438 C:/server/src/go/src/discovery/registry/registry.go:222 Polls from(CLII) new connection(1)
INFO 01/10-15:22:34.440 C:/server/src/go/src/discovery/registry/registry.go:228 Polls from(CLII) reuse connection(2)
INFO 01/10-15:22:44.219 C:/server/src/go/src/discovery/registry/registry.go:373 DelConns from(DESKTOP-9NFHKD0) delete(1)
ERROR 01/10-15:22:44.219 http-access-log path=/discovery/polls ret=-304 msg=-304 tim
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