Building Microservices with Spring Cloud Consul: A Comprehensive Demo

Objective

Spring Cloud Consul" project, which is a part of the Spring Cloud ecosystem and provides integration with HashiCorp Consul, a popular service mesh and service discovery tool.

Spring Cloud Consul enables Spring Boot applications to register themselves with Consul and discover other services that are registered with Consul. It also provides features such as distributed configuration, service routing, and health checking.

Spring consul installation

Download the package from any of the OS package managers. For Instance below are the package manager for mac OS

brew tap hashicorp/tap
brew install hashicorp/tap/consul

Verify that Consul is installed correctly by running the following command in your terminal or command prompt

consul --version

Adding Spring consul to the project

following dependencies were required to integrate the existing project with

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <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>

Optionally we can also add a spring-boot starter dependency to test the changes

Once the dependencies are added make sure to add the configuration details to application.yml

spring:
  application:
    name: app01 
  cloud:
    consul:
      config:
        fail-fast: true
      host: 'remote server host name'
      port: remote server port '
  config:
    import: 'consul:' # spring config is mandatory for versions more than spring-boot 2.4

Adding key values to the remote server

1. Open the Consul web UI by visiting http://<consul-host>:<consul-port>/ui in your web browser.

2. Create a folder in structure in such a way that it config/<<application-name>>

3. Navigate to the "Key/Value" tab on the left sidebar.

4. Click on the "+" icon next to the "Keys" header to create a new key.

5. Enter the key name and value in the form that appears, and click the "Create" button.

   Testing

   To test/consume the props from remote server, make a Configuration class and annotate with @ConfigurationalProperties

6.  @ConfigurationProperties(prefix = "my")
    @Data
    public class MyConfig {
   
        private String userName;
        private String password;
    }
   

   And auto-wire MyConfig bean in RestController class. Create a GET mapping annotation and return the MyConfig instance

7.  @RestController
    public class TestController {
   
        @Autowired
        MyConfig myConfig;
   
        @GetMapping("/getConfigData")
        public MyConfig getConfig(){
            return myConfig;
        }
    }
   

   navigate the http://localhost:8080/getConfigData, application should start successfully and verify the changes

Code Reference

Please email to venothanand91@gmail.com for any queries to support.

Thanks