Microservice governance (nocas)

Implement microservice governance （Nocas）

1、 Introduction to service governance

Implement calls between microservices , We can go through HTTP Client tools complete , But we need to put the network address of the service provider （IP, port ） And so on , There will be the following problems ：

• Once the service provider address changes , You need to modify the code manually
• Once there are multiple service providers , Unable to implement load balancing function
• Once services become more and more , It is difficult to maintain the call relationship manually

So what should be done , At this time, we need to dynamically implement service governance through the registry .

What is service governance

Service governance is the core and basic module of microservice architecture . It is used to realize the automatic registration and discovery of various micro services .

• ** Service registration ：** In the service governance framework , Will build a registry , Each service unit registers the details of its own services with the registry . And form a list of services in the registry , The service registry needs to monitor whether the services in the list are available by heartbeat , If not available , You need to eliminate unavailable services from the service list .
• ** Service discovery ：** The service invoker consults the service registry , And get the instance list of all services , Achieve access to specific service instances .
  
  Through the call graph above, you will find , Besides microservices , Another component is the service registry , It is a very important component of the microservice architecture , In the microservice architecture, it mainly plays a role of coordinator . The registry generally includes the following functions ：

1、 Service discovery

** Service registration ：** Keep information about service providers and service callers

** Service subscription ：** The service caller subscribes to the service provider's information , The registry pushes the provider's information to subscribers

2、 Service configuration

** Configure subscription ：** Service providers and service callers subscribe to microservice related configurations

** Configure distribution ：** Actively push configuration to service providers and service callers

3、 Service health testing

Testing the health of service providers , If an exception is found , Execute the service

Common registries

• Zookeeper

  Zookeeper Is a distributed services framework , yes Apache Hadoop A subproject of , It is mainly used to solve some data management problems often encountered in distributed applications , Such as ： Unified naming service 、 State synchronization service 、 Cluster management 、 Management of distributed application configuration items .

• Eureka
  Eureka yes Spring Cloud Netflix Important components in , The main function is to do service registration and discovery . But now The source has been closed .

• Consul

  Consul Is based on Go Open source tools for language development , Mainly for distributed , The service system provides service registration , Service discovery and configuration management .Consul The functions of are very practical , These include ： Service registration / Find out 、 Health detection 、Key/Value Storage 、 Multi data center and distributed consistency guarantee .Consul Itself is just a binary executable , So the installation and deployment are very simple , Just download it from the official website , After executing the corresponding startup script .

• Nacos

  Nacos It is a dynamic service discovery that is easier to build cloud native applications 、 Configuration management and service management platform . He is Spring Cloud Alibaba One of the components , Responsible for service registration discovery and service configuration , Think of it this way nacos=eureka + config

2、Nacos brief introduction

Nacos Committed to helping discover 、 Configure and manage microservices .Nacos Provides a set of features that are easy to use , Help to quickly realize dynamic service discovery 、 Service configuration 、 Service metadata and traffic management .

As can be seen from the above introduction ,nacos It's a registry , It is used to manage various microservices from registrants .

3、Nacos Practical introduction

3.1、 build Nacos Environmental Science

The first 1 Step ： install nacos

Download address ：https://github.com/alibaba/nacos/releases, download zip Format installation package , Decompress after the user .

The first 2 Step ： start-up nacos

## Toggle directory cd nacos/bin## Start command startup.cmd -m standalone

The first 3 Step ： visit nacos

Open the browser and type http://localhost:8848/nacos, Access to services , The default password is nacos/nacos

3.2、 Register the microservice to Nacos

The first 1 Step : In global public pom.xml Add the following version dependency management to

   <!-- Inherit Springboot The parent project , To limit Springboot edition ,  Be careful ：SpringBoot The version must be  alibaba cloud Supported versions -->
   <parent>
        <artifactId>spring-boot-starter-parent</artifactId>
        <groupId>org.springframework.boot</groupId>
        <version>2.2.1.RELEASE</version>
    </parent>

    <dependencies>

        <!-- Manual introduction Springboot  rely on -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.16</version>
        </dependency>
    </dependencies>

    <!-- introduce alibaba  Parent project version limit for -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.2.1.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

The first 2 Step ： stay pom.xml Add Nacos Dependence

<!--nacos client -->
<dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>2.2.1.RELEASE</version>
       </dependency>

The first 3 Step ： Add on the startup class @EnableDiscoveryClient annotation

The first 4 Step ： stay application.yml Add nacos Address of service

spring:	
	cloud:		
		nacos:			
			discovery:				
				server-addr: 127.0.0.1:8848
	application:
    	name: user-service

The first 4 Step ： Start the service , see Nacos Is there a registered microservice in the control panel of

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The first 1 Step : In global public pom.xml Add the following version dependency management to

   <!-- Inherit Springboot The parent project , To limit Springboot edition ,  Be careful ：SpringBoot The version must be  alibaba cloud Supported versions -->
   <parent>
        <artifactId>spring-boot-starter-parent</artifactId>
        <groupId>org.springframework.boot</groupId>
        <version>2.2.1.RELEASE</version>
    </parent>

    <dependencies>

        <!-- Manual introduction Springboot  rely on -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.16</version>
        </dependency>
    </dependencies>

    <!-- introduce alibaba  Parent project version limit for -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.2.1.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

The first 2 Step ： stay pom.xml Add Nacos Dependence

<!--nacos client -->
<dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>2.2.1.RELEASE</version>
       </dependency>

The first 3 Step ： Add on the startup class @EnableDiscoveryClient annotation

The first 4 Step ： stay application.yml Add nacos Address of service

spring:	
	cloud:		
		nacos:			
			discovery:				
				server-addr: 127.0.0.1:8848
	application:
    	name: user-service

The first 4 Step ： Start the service , see Nacos Is there a registered microservice in the control panel of

3.3、 Service configuration center Nacos

First step ： Introduce dependencies

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

<!-- send bootstrap To configure ⽂ Pieces of ⽣ effect -->
<dependency>
 <groupId>org.springframework.cloud</groupId>
 <artifactId>spring-cloud-context</artifactId>
</dependency>

The second step ： Create written bootstrap.yaml⽂ Pieces of

spring:
 cloud:
 nacos:
 config:
 server-addr: localhost:8848
 file-extension: yaml
 application:
 name: user-service
 profiles:
 active: dev

A detailed version

spring.cloud.nacos.config.server-addr=192.168.0.139:8849
#spring.cloud.nacos.config.group=DEFAULT_GROUP
spring.cloud.nacos.config.namespace = 2a3c21b4-94cf-4ce9-9cf5-2d05b44f0eaa
spring.cloud.nacos.config.file-extension = properties

spring.cloud.nacos.discovery.server-addr=192.168.0.139:8849
spring.cloud.nacos.discovery.namespace= 2a3c21b4-94cf-4ce9-9cf5-2d05b44f0eaa
spring.cloud.nacos.discovery.service=${
    spring.application.name}

The third step ： stay nacos Create the specified profile on
name ：user-service-dev.yaml


Step four : Confirm release