SpringCloudAlibaba之Nacos

1、简介

????????Nacos支持基于DNS和基于RPC的服务发现，服务端可以通过SDK或者Api进行服务注册，相应的服务消费者可以使用DNS或者Http查找的方式获取服务列表。Spring Cloud 服务注册中心的服务器很多，如 Zookeeper、Eureka、Consul 等。 Spring Cloud Alibaba 中使用的注册中心为 Alibaba 的中间件 Nacos。

2、下载

下载地址：https://github.com/alibaba/nacos/releases

2、启动

2.1、单机启动

下载解压后运行。

# 1、进入bin目录
startup.cmd -m standalone  # windows系统
startup.sh -m standalone   # linux系统

2.2、使用外部数据源

使用mysql数据库，外部数据源初始化。

# 1、在conf目录下有sql初始化脚本
mysql -uroot -p   # 登录数据库
create database nacos;  # 创建数据库
use nacos;     # 使用nacos数据库
source **/mysql-schema.sql  # 初始化sql文件

?配置文件中配置使用外部数据源

#*************** Config Module Related Configurations ***************#
# spring.datasource.platform=mysql   # 此方式也过期
# 使用外部数据源配置
spring.sql.init.platform=mysql   # 新版设置数据库服务类型方式

### Count of DB:
db.num=1

### Connect URL of DB:
db.url.0=jdbc:mysql://localhost:3306/nacos?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=UTC
db.user.0=root
db.password.0=146815

### Connection pool configuration: hikariCP
db.pool.config.connectionTimeout=30000
db.pool.config.validationTimeout=10000
db.pool.config.maximumPoolSize=20
db.pool.config.minimumIdle=2

2.3、配置文件详解（application.properties ）

#*************** Spring Boot Related Configurations ***************#
### Default web context path:
server.servlet.contextPath=/nacos
### Include message field
server.error.include-message=ALWAYS
### 默认端口号
server.port=8848

#*************** Network Related Configurations ***************#
### If prefer hostname over ip for Nacos server addresses in cluster.conf:
# nacos.inetutils.prefer-hostname-over-ip=false
### Specify local server's IP:
# nacos.inetutils.ip-address=

#*************** Config Module Related Configurations ***************#
### If use MySQL as datasource:
### Deprecated configuration property, it is recommended to use `spring.sql.init.platform` replaced.
# spring.datasource.platform=mysql   # 此方式也过期
# 使用外部数据源配置
spring.sql.init.platform=mysql   # 新版设置数据库服务类型方式

### Count of DB:
db.num=1

### Connect URL of DB:
db.url.0=jdbc:mysql://localhost:3306/nacos?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=UTC
db.user.0=root
db.password.0=146815

### Connection pool configuration: hikariCP
db.pool.config.connectionTimeout=30000
db.pool.config.validationTimeout=10000
db.pool.config.maximumPoolSize=20
db.pool.config.minimumIdle=2

#*************** Naming Module Related Configurations ***************#
### If enable data warmup. If set to false, the server would accept request without local data preparation:
# nacos.naming.data.warmup=true

### If enable the instance auto expiration, kind like of health check of instance:
# nacos.naming.expireInstance=true

### Add in 2.0.0
### The interval to clean empty service, unit: milliseconds.
# nacos.naming.clean.empty-service.interval=60000

### The expired time to clean empty service, unit: milliseconds.
# nacos.naming.clean.empty-service.expired-time=60000

### The interval to clean expired metadata, unit: milliseconds.
# nacos.naming.clean.expired-metadata.interval=5000

### The expired time to clean metadata, unit: milliseconds.
# nacos.naming.clean.expired-metadata.expired-time=60000

### The delay time before push task to execute from service changed, unit: milliseconds.
# nacos.naming.push.pushTaskDelay=500

### The timeout for push task execute, unit: milliseconds.
# nacos.naming.push.pushTaskTimeout=5000

### The delay time for retrying failed push task, unit: milliseconds.
# nacos.naming.push.pushTaskRetryDelay=1000

### Since 2.0.3
### The expired time for inactive client, unit: milliseconds.
# nacos.naming.client.expired.time=180000

#*************** CMDB Module Related Configurations ***************#
### The interval to dump external CMDB in seconds:
# nacos.cmdb.dumpTaskInterval=3600
### The interval of polling data change event in seconds:
# nacos.cmdb.eventTaskInterval=10
### The interval of loading labels in seconds:
# nacos.cmdb.labelTaskInterval=300
### If turn on data loading task:
# nacos.cmdb.loadDataAtStart=false
#*************** Metrics Related Configurations ***************#
### Metrics for prometheus
#management.endpoints.web.exposure.include=*

### Metrics for elastic search
management.metrics.export.elastic.enabled=false
#management.metrics.export.elastic.host=http://localhost:9200
### Metrics for influx
management.metrics.export.influx.enabled=false
#management.metrics.export.influx.db=springboot
#management.metrics.export.influx.uri=http://localhost:8086
#management.metrics.export.influx.auto-create-db=true
#management.metrics.export.influx.consistency=one
#management.metrics.export.influx.compressed=true

#*************** Access Log Related Configurations ***************#
### If turn on the access log:
server.tomcat.accesslog.enabled=true

### The access log pattern:
server.tomcat.accesslog.pattern=%h %l %u %t "%r" %s %b %D %{User-Agent}i %{Request-Source}i

### The directory of access log:
server.tomcat.basedir=file:.

#*************** Access Control Related Configurations ***************#
### If enable spring security, this option is deprecated in 1.2.0:
#spring.security.enabled=false

### The ignore urls of auth
nacos.security.ignore.urls=/,/error,/**/*.css,/**/*.js,/**/*.html,/**/*.map,/**/*.svg,/**/*.png,/**/*.ico,/console-ui/public/**,/v1/auth/**,/v1/console/health/**,/actuator/**,/v1/console/server/**

### The auth system to use, currently only 'nacos' and 'ldap' is supported:
nacos.core.auth.system.type=nacos
#从 nacos2.2.0.1 版本开始，nacos 配置文件中去掉了默认的鉴权配置，需要用户手工添加，否则无法启动 nacos。（注：nacos.core.auth.*相关配置。
### If turn on auth system:
nacos.core.auth.enabled=false

### Turn on/off caching of auth information. By turning on this switch, the update of auth information would have a 15 seconds delay.
nacos.core.auth.caching.enabled=false

### Since 1.4.1, Turn on/off white auth for user-agent: nacos-server, only for upgrade from old version.
nacos.core.auth.enable.userAgentAuthWhite=false

### Since 1.4.1, worked when nacos.core.auth.enabled=true and nacos.core.auth.enable.userAgentAuthWhite=false.
### The two properties is the white list for auth and used by identity the request from other server.
nacos.core.auth.server.identity.key=xxx
nacos.core.auth.server.identity.value=ccc

### worked when nacos.core.auth.system.type=nacos
### The token expiration in seconds:
nacos.core.auth.plugin.nacos.token.cache.enable=false
nacos.core.auth.plugin.nacos.token.expire.seconds=18000
### The default token (Base64 String):
nacos.core.auth.plugin.nacos.token.secret.key=adadafaffafafefefefefewdqwdwefe089989=

### worked when nacos.core.auth.system.type=ldap，{0} is Placeholder,replace login username
#nacos.core.auth.ldap.url=ldap://localhost:389
#nacos.core.auth.ldap.basedc=dc=example,dc=org
#nacos.core.auth.ldap.userDn=cn=admin,${nacos.core.auth.ldap.basedc}
#nacos.core.auth.ldap.password=admin
#nacos.core.auth.ldap.userdn=cn={0},dc=example,dc=org
#nacos.core.auth.ldap.filter.prefix=uid
#nacos.core.auth.ldap.case.sensitive=true

#*************** Istio Related Configurations ***************#
### If turn on the MCP server:
nacos.istio.mcp.server.enabled=false
#*************** Core Related Configurations ***************#

### set the WorkerID manually
# nacos.core.snowflake.worker-id=

### Member-MetaData
# nacos.core.member.meta.site=
# nacos.core.member.meta.adweight=
# nacos.core.member.meta.weight=

### MemberLookup
### Addressing pattern category, If set, the priority is highest
# nacos.core.member.lookup.type=[file,address-server]
## Set the cluster list with a configuration file or command-line argument
# nacos.member.list=192.168.16.101:8847?raft_port=8807,192.168.16.101?raft_port=8808,192.168.16.101:8849?raft_port=8809
## for AddressServerMemberLookup
# Maximum number of retries to query the address server upon initialization
# nacos.core.address-server.retry=5
## Server domain name address of [address-server] mode
# address.server.domain=jmenv.tbsite.net
## Server port of [address-server] mode
# address.server.port=8080
## Request address of [address-server] mode
# address.server.url=/nacos/serverlist

#*************** JRaft Related Configurations ***************#

### Sets the Raft cluster election timeout, default value is 5 second
# nacos.core.protocol.raft.data.election_timeout_ms=5000
### Sets the amount of time the Raft snapshot will execute periodically, default is 30 minute
# nacos.core.protocol.raft.data.snapshot_interval_secs=30
### raft internal worker threads
# nacos.core.protocol.raft.data.core_thread_num=8
### Number of threads required for raft business request processing
# nacos.core.protocol.raft.data.cli_service_thread_num=4
### raft linear read strategy. Safe linear reads are used by default, that is, the Leader tenure is confirmed by heartbeat
# nacos.core.protocol.raft.data.read_index_type=ReadOnlySafe
### rpc request timeout, default 5 seconds
# nacos.core.protocol.raft.data.rpc_request_timeout_ms=5000

#*************** Distro Related Configurations ***************#

### Distro data sync delay time, when sync task delayed, task will be merged for same data key. Default 1 second.
# nacos.core.protocol.distro.data.sync.delayMs=1000

### Distro data sync timeout for one sync data, default 3 seconds.
# nacos.core.protocol.distro.data.sync.timeoutMs=3000

### Distro data sync retry delay time when sync data failed or timeout, same behavior with delayMs, default 3 seconds.
# nacos.core.protocol.distro.data.sync.retryDelayMs=3000

### Distro data verify interval time, verify synced data whether expired for a interval. Default 5 seconds.
# nacos.core.protocol.distro.data.verify.intervalMs=5000

### Distro data verify timeout for one verify, default 3 seconds.
# nacos.core.protocol.distro.data.verify.timeoutMs=3000

### Distro data load retry delay when load snapshot data failed, default 30 seconds.
# nacos.core.protocol.distro.data.load.retryDelayMs=30000

### enable to support prometheus service discovery
#nacos.prometheus.metrics.enabled=true

### Since 2.3
#*************** Grpc Configurations ***************#
## sdk grpc(between nacos server and client) configuration
## Sets the maximum message size allowed to be received on the server.
#nacos.remote.server.grpc.sdk.max-inbound-message-size=10485760

## Sets the time(milliseconds) without read activity before sending a keepalive ping. The typical default is two hours.
#nacos.remote.server.grpc.sdk.keep-alive-time=7200000

## Sets a time(milliseconds) waiting for read activity after sending a keepalive ping. Defaults to 20 seconds.
#nacos.remote.server.grpc.sdk.keep-alive-timeout=20000
## Sets a time(milliseconds) that specify the most aggressive keep-alive time clients are permitted to configure. The typical default is 5 minutes
#nacos.remote.server.grpc.sdk.permit-keep-alive-time=300000

## cluster grpc(inside the nacos server) configuration
#nacos.remote.server.grpc.cluster.max-inbound-message-size=10485760

## Sets the time(milliseconds) without read activity before sending a keepalive ping. The typical default is two hours.
#nacos.remote.server.grpc.cluster.keep-alive-time=7200000

## Sets a time(milliseconds) waiting for read activity after sending a keepalive ping. Defaults to 20 seconds.
#nacos.remote.server.grpc.cluster.keep-alive-timeout=20000

## Sets a time(milliseconds) that specify the most aggressive keep-alive time clients are permitted to configure. The typical default is 5 minutes
#nacos.remote.server.grpc.cluster.permit-keep-alive-time=300000

注：从 nacos2.2.0.1 版本开始，nacos 配置文件中去掉了默认的鉴权配置，需要用户手工添加，否则无法启动 nacos。

nacos.core.auth.*  # 相关配置参数

2.4、集群配置（cluster.conf）

#it is ip
#example
192.168.16.101:8848
192.168.16.102:8848
192.168.16.103:8848

注：集群启动使用命令（默认是使用cluster模式启动的）：startup.cmd/startup.sh。

2.5、微服务使用nacos集群作为注册中心配置

spring:
  application:
    name: consumer-default-8084
  cloud:
    nacos:
      discovery:
      # nacos 集群模式下服务配置，使用逗号隔开
        server-addr: ip1:8848,ip2:8848,ip3:8848

3、注册中心使用案例

微服务使用nacos作为注册中心使用

3.1、添加依赖

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>

3.2、服务配置nacos信息

spring:
  application:
    name: consumer-openfeign-8084
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
        # 配置临时实例还是持久实例：true 为临时实例，false 为持久实例。
        ephemeral: true  # 默认值为true
        group: weilong                # 指定当前微服务属于的namespace、group
        namespace: fkasjfkasjsj       # 想同namespace和group下的微服务才能相互调用
        # 如果配置鉴权需要配置用户名和密码
        username: nacos
        password: nacos

注：临时实例与持久实例的实例存储的位置与健康检测机制是不同的。

1、临时实例：默认情况。服务实例仅会注册在 Nacos 内存，不会持久化到 Nacos 磁盘。其健康检测机制为 Client 模式，即 Client 主动向 Server 上报其健康状态。默认心跳间隔为5 秒。在 15 秒内 Server 未收到 Client 心跳，则会将其标记为“不健康”状态；在 30 秒内若收到了 Client 心跳，则重新恢复“健康”状态，否则该实例将从 Server 端内存清除。

2、持久实例：服务实例不仅会注册到 Nacos 内存，同时也会被持久化到 Nacos 磁盘。其健康检测机制为 Server 模式，即 Server 会主动去检测 Client 的健康状态，默认每 20 秒检测一次。健康检测失败后服务实例会被标记为“不健康”状态，但不会被清除，因为其是持久化在磁盘的。

3.3、主启动类

@SpringBootApplication
@EnableDiscoveryClient  // 此注解在nacos2.2.1版本以后可以省略
public class ApplicationConsumer8082 {
    public static void main(String[] args) {
        SpringApplication.run(ApplicationConsumer8082.class, args);
    }
}

4、配置中心

微服务使用nacos作为配置中心使用

4.1、添加依赖

 <dependency>
     <groupId>com.alibaba.cloud</groupId>
     <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>

4.2、服务配置使用nacos作为配置中心的配置

spring:
  config:
  # 表明使用配置中心的dataid名称
    import:
      - optional:nacos:${spring.application.name}-${spring.profiles.active}.${spring.cloud.nacos.config.file-extension}
  application:
    name: provider-nacos-config
  cloud:
    nacos:
#      discovery:
#        server-addr: localhost:8848
#        group: weilong
      config:         # 配置中心信息
        server-addr: localhost:8848
        file-extension: yml   # 配置中心配置文件类型
        namespace: adafafaf   # 指定配置文件所属的namespace和group
        group: weilong
        prefix: provider-nacos-config 
        # 如果配置鉴权需要配置用户名和密码
        username: nacos
        password: nacos
  profiles:            # 选择当前使用环境
    active: dev

4.3、使用动态刷新

@RestController
@RequestMapping("/provider01")
@RefreshScope  // 开启nacos动态配置刷新功能
public class RestTestController {    
    @Value("${test.name}")
    private String name;
    @Autowired
    private DepartService departService;

    @GetMapping("/test")
    public String test(){
        return "hello provider01" + name;
    }
}

4.4、配置中心dataId命名规则

dataId组成格式：

${prefix}-${spring.profiles.active}.${file-extension}  
##注：
# 1、prefix默认值为spring.application.name的值，可以通过spring.cloud.nacos.config.prefix进行覆盖
# 2、spring.profiles.active不存在时，连接符'-'也不存在
# 3、file-extension可以通过spring.cloud.nacos.config.file-extension配置

4.5、共享配置、扩展配置和应用配置

????????共享配置，扩展配置，当前服务配置。若在三个配置中具有相同属性设置，但它们具有不同的值，那么，后加载的会将先加载的给覆盖。即这三类配置的优先级由低到高是：共享配置，扩展配置，当前服务配置 。

spring:
  config:
  # 表明使用配置中心的dataid名称
    import:
      - optional:nacos:${spring.application.name}-${spring.profiles.active}.${spring.cloud.nacos.config.file-extension}
  application:
    name: provider-nacos-config
  cloud:
    nacos:
      config:         # 配置中心信息
      server-addr: localhost:8848
      file-extension: yml   # 配置中心配置文件类型
      # 同一个group中的不同服务可以共享
      shared-configs: 
        data-id: ***.yml
          refresh: true
      # 不同group中不同服务共享
      extension-configs: 
        data-id: ***.yml
          refresh: true

5、动态刷新配置原理

????????Nacos Config Server 中配置数据的变更，Nacos Config Client 是如何知道的呢？Nacos 采用的是长轮询模型。长轮询模型整合了 Push 与 Pull 模型的优势。Client 仍定时发起 Pull 请求，查看 Server端数据是否更新。若发生了更新，则 Server 立即将更新数据以响应的形式 Push 给 Client 端；若没有发生更新，Server 端并不向 Client 进行 Push，而是临时性的保持住这个连接一段时间。若在此时间段内，Server 端数据发生了变更，则立即将变更数据 Push 给 Client。若仍未发生变更，则放弃这个连接。等待着下一次 Client 的 Pull 请求。长轮询模型，是 Push 与 Pull 模型的整合，既降低了 Push 模型中长连接的维护问题，又降低了 Push 模型实时性较低的问题。

总结：本文介绍nacos作为配置中心和注册中心的使用，同时介绍了nacos集群和如何使用外部数据源的配置，并且进行案例演示，帮助大家快速入门nacos的使用。

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