How to migrate spring boot admin server and client into one spring boot application

Question

I'm using spring boot admin to monitor my springboot application, it's pretty good. But I need to start spring boot admin server firstly and then start my application which contains spring boot client.

Is there a way to contain the spring boot server into my spring boot application, make them looks like one application, so that I can just start my application, then the server started and the client registerd to the server. The ultimate purpose is my application is running on port 8080, and the spring boot admin is running on port 8081.

I have checked this thread: How to run spring boot admin client and server in same application but it doesn't contain any details, I can't implement with the possible solution.

PS: I know I can package the spring boot admin server, and then write the start.sh, startup the server firstly and then start my application, but it's not a pretty solution.

Anyone can help?

SpringBoot version: 2.3.4.RELEASE Spring Boot Admin version: 2.3.0

Answer 1

Technically this should be possible to integrate both in one single application, but I'm afraid you'll run into problems soon.

But let us give it a try...

Reference: Proof of concept GitHub

Problems with this approach:

• launch 2 servers on startup: the client on port 8080, and the admin-server on port 8081
• the client and the server should have separate configurations

Let's start with the configuration

We could separate the multiple configurations by using a profile so we can take advantage of Profile Specific Files

application-client.properties

server.address=localhost
spring.boot.admin.client.url = http://localhost:8081/
management.endpoints.web.exposure.include = *
management.endpoint.health.show-details= always

spring.application.name=client-app
spring.boot.admin.client.instance.name=client-app

application-admin.properties

server.address=localhost
server.port=8081

Launch the server, and the client with the correct profile.

DemoApplication

public class DemoApplication {

    public static void main(String[] args) throws Exception {
        SpringApplication admin = new SpringApplication(DemoAdminServer.class);
        admin.setAdditionalProfiles("admin");
        admin.run(args);

        SpringApplication client = new SpringApplication(DemoClient.class);
        client.setAdditionalProfiles("client");
        client.run(args);
    }
}

@EnableAdminServer
@Configuration
@EnableAutoConfiguration
@Profile("admin")
class DemoAdminServer {

}

@SpringBootApplication
@RestController
@Profile("client")
class DemoClient {

    @GetMapping
    public String hello(){
        return "Hello world!";
    }

}

Launch the Application, and we should be good...

• client
• admin-server

---

If you have two separate applications, then in your client you could launch the admin-server via a process.

@SpringBootApplication
public class ClientApplication {

    public static void main(String[] args) throws Exception{
        startAdminServer();
        SpringApplication.run(DemoApplication.class, args);
    }

    static void startAdminServer() throws Exception {
        new ProcessBuilder()
                .redirectErrorStream(true)
                .command("cmd.exe",
                         "/c",
                         "java -jar path_to_your_admin_server.jar")
                .start();
    }
}

Answer 2

Explore spring multi-module feature for solving your use-case.

Have your spring boot server as a parent project and add all your spring boot client projects as individual modules. All these individual modules are nothing but a spring boot application. You can package and deploy those individual modules on any different ports.

Answer 3

An easier solution would be to have the applications run inside containers and will be better to have them isolated instead of turning them into a monolith.

You can build your applications using docker (https://spring.io/guides/gs/spring-boot-docker/)

Basically you will have a docker file for each app, something like this:

FROM openjdk:8-jdk-alpine
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar
ENTRYPOINT ["java","-jar","/app.jar"]

And start them using docker-compose

version: '3.7'
services:
  spring-boot-admin:
    image: spring-boot-admin-image
    container_name: spring-boot-admin
    ports:
      - 8081:8081
    healthcheck:
      test: "curl --fail --silent localhost:8081/actuator/health | grep UP || exit 1"
      interval: 20s
      timeout: 5s
      retries: 5
      start_period: 40s

  spring-boot-client:
    image: spring-boot-client-image
    container_name: spring-boot-client
    ports:
      - 8080:8080
    depends_on:
      - spring-boot-admin

The depends_on will make sure your spring-boot-client starts after spring-boot-admin is healthy