Environment Setup

Spring Cloud Alibaba 2022 requires Spring Boot 3.0+ and JDK 17 or higher. Check the official documentation for compatibility details.

The project structure uses a Maven multi-module setup with the following parent pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>spring-cloud-alibaba-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-cloud-alibaba-demo</name>
    <description>spring-cloud-alibaba-demo</description>

    <packaging>pom</packaging>

    <properties>
        <java.version>17</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>3.0.2</spring-boot.version>
        <spring-cloud-alibaba.version>2022.0.0.0-RC2</spring-cloud-alibaba.version>
        <spring-cloud.version>2022.0.0</spring-cloud.version>
    </properties>

    <modules>
        <module>consumerservice01</module>
        <module>providerservice01</module>
    </modules>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>${spring-cloud-alibaba.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>17</source>
                    <target>17</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>${spring-boot.version}</version>
                <configuration>
                    <mainClass>com.example.springcloudalibabademo.SpringCloudAlibabaDemoApplication</mainClass>
                    <skip>true</skip>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Nacos Overview and Installation

Nacos stands for Dynamic Naming and Configuration Service. It provides dynamic service discovery, configuration management, and service management capabilities for building cloud-native applications.

Download and run Nacos Server, then access the login page at port 8848. The default username and password are both nacos.

Service Registration and Discovery

To enable service registration and discovery, add the Nacos discovery dependency to each module's pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>consumerservice01</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>consumerservice01</name>
    <description>consumerservice01</description>

    <parent>
        <artifactId>spring-cloud-alibaba-demo</artifactId>
        <groupId>com.example</groupId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <packaging>jar</packaging>

    <properties>
        <java.version>17</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    </properties>

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

</project>

Create an application.yml file to configure the Nacos Server address:

spring:
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848

  application:
    name: consumerservice01

server:
  port: 8890

After starting the consumer service, it appears in the service list under Nacos management console.

Unlike Eureka, Nacos does not require the @EnableDiscoveryClient annotation on the main application class.

Nacos Service Tiered Storage Model

The storage model consists of three levels:

• Level 1: Service (e.g., consumerservice01)
• Level 2: Cluster
• Level 3: Instance

spring:
  cloud:
    nacos:
      discovery:
        cluster-name: SH

Restart the application to see the cluster name displayed.

Environment Isolation

Namespace

Namespaces provide tenant-level configuration isolation. The same Group or Data ID can exist in different namespaces.

Use case: Typically used for environment isolation, such as separating test and production environments.

Group

Groups provide a secondary level of isolation beneath namespaces.

Use case: Used to differentiate between projects when multiple projects share a single Nacos instance.

Key points:

1. Services can only communicate with each other when they are in the same namespace and same group
2. Services registered to Nacos belong to the public namespace and DEFAULT_GROUP by default

Configure namespace and group in application.yml:

spring:
  cloud:
    nacos:
      discovery:
        namespace: 8ff552f0-0212-43b2-8ea0-e4c2aa359084
        group: testgroup1

Load Balancing

Enable load balancing in application.yml:

spring:
  cloud:
    loadbalancer:
      nacos:
        enabled: true

Adjust instance weights in the Nacos console—higher weights increase the probability of that instance being selected. The implementation details are in the NacosLoadBalancer class.

Nacoss Configuration Center

The configuration center solves the coupling problem between microservices and configuration files. Without it, modifying configuration across multiple service instances would require updating numerous files and restarting services.

A challenge arises: the application.yml file is loaded after the application starts, but connection to Nacos requires knowing the Nacos Server address beforehand.

The solution involves using a bootstrap.yml file, which loads during application startup before the main configuration. This allows the Nacos Server address to be specified early in the bootstrap process. Spring Cloud Config follows the same principle.

Add the Nacos configuration client dependencies:

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

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-bootstrap</artifactId>
    <version>3.0.1</version>
</dependency>

Create bootstrap.yml with the configuration:

spring:
  cloud:
    nacos:
      config:
        server-addr: 127.0.0.1:8848
        file-extension: yaml
        namespace: 8ff552f0-0212-43b2-8ea0-e4c2aa359084
        group: DEFAULT_GROUP

  application:
    name: consumerservice
  profiles:
    active: dev

Create a corresponding configuration file in the Nacos console matching the service name, namespace, and group settings.

Configuration Hot Reload

Two approaches exist for hot reloading:

1. Add the @RefreshScope annotation to classes using @Value injection
2. Use the @ConfigurationProperties annotation instead of @Value

Multi-Environment Configuration Sharing

Configuration files created in the Nacos console support profile-based organization and shared configuration across environments when properly grouped.