Spring Boot Actuator with Admin Server

Spring Boot Actuator with Admin Server | Actuator: Production Ready Endpoints (Readymade services).

If one application is developed and placed in production then we need a few additional services. Example (additional services):-

• Is the Application started?
• What are objects created?
• What are properties loaded?
• What is the information on the Application?
• Schedulers details?
• Caches Enabled?
• Logger Details?
• Threads, Heap details.

These additional services can be added to our project without writing explicit code. For this, we can use an Actuator. It is a pre-defined code, we can enable/disable these services.

• Generally, for every REST/microservices Application, we should enable Actuator.
• We can check them in the dev/test environment also, but it is mainly designed for the production environment.

While creating the project we should add one dependency: spring-boot-starter-actuator

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

When we add the above dependency then 2 services(Endpoints) are activated by default with the base path /actuator. URL: http://localhost:8080/actuator. Here default endpoints are health and info.

To demonstrate let us create a spring starter project using the following dependencies:- Spring Web, Spring Boot DevTools, and Spring Boot Actuator. Start the application.

Actuator Health

The health endpoints show the status of the application:- UP/DOWN. Enter URL: http://localhost:8080/actuator/health

To see disk space(RAM details, total, free, allocated data):-

management.endpoint.health.show-details=always

Default is never (don’t show), we can show the same details only after login:-

management.endpoint.health.show-details=when-authorized

To disable health:-

management.endpoint.health.enabled=false

Actuator info

The info endpoint shows the meta-data of the application Like Project Name, version, client, location, copyrights info, etc. Syntax to add info is:-

info.key=value

For example, in application.properties:-

info.app.title=ABCD-APP
info.app.version=3.2 GA
info.client.name=KnowProgram
info.client.license=KnowProgram-NEW

URL: http://localhost:8080/actuator/info

Actuator Endpoints

Q) How can we modify the default base path?
Add below key:-

management.endpoints.web.base-path=/mytest

We can use even / also a base path, but you may not see all endpoints but we can access still with the full path as:- http://localhost:8080/info [It is not recommended]

Q) How can we activate all endpoints? (or) Specific endpoints?
To activate all endpoints:-

management.endpoints.web.exposure.include=*

To activate Specific:-

management.endpoints.web.exposure.include=health,beans,env

Q) How can we exclude specific endpoints?

# to activate all
management.endpoints.web.exposure.include=*

# to exclude provided
management.endpoints.web.exposure.exclude=health,info,beans,env

1. beans: To check what are objects created in the application we can use this endpoint. Enable this endpoint:-

management.endpoints.web.exposure.include=*
// (or)
management.endpoints.web.exposure.include=beans

URL: http://localhost:8080/actuator/beans

2. env: Environment – Properties (key=val) that are loaded into the Application. URL:
   http://localhost:8080/actuator/env
3. configprops: To find keys loaded into the app using @ConfigurationProperties. URL: http://localhost:8080/actuator/configprops
4. scheduledtasks: To find your scheduled tasks. URL: http://localhost:8080/actuator/scheduledtasks
5. mappings: For a given Request URL which class and method are executed, what is the output, etc. URL: http://localhost:8080/actuator/mappings

Admin Server

If we have multiple microservices then we have to check every microservices manually for Actuators. We can avoid that by using the Admin Server.

Admin Server: It provides one common UI for All microservices Actuator outputs. Now we don’t need to check every microservices URL manually.

Admin Server Project

1. Create a Spring starter project SpringBoot2AdminServer, and add the dependency:- Codecentric’s Spring Boot Admin Server (spring-boot-admin-starter-server)

<dependency>
    <groupId>de.codecentric</groupId>
    <artifactId>spring-boot-admin-starter-server</artifactId>
</dependency>

2. In application.properties:-

# any port number
server.port=9988

3. At starter class: @EnableAdminServer
4. Run the application.

Microservice Project

1. Create a Spring starter project SpringBoot2EmployeProject, and add dependencies:- Spring Web, Spring Boot Actuator, Codecentric’s Spring Boot Admin Client (spring-boot-admin-starter-client).

<dependency>
    <groupId>de.codecentric</groupId>
    <artifactId>spring-boot-admin-starter-client</artifactId>
</dependency>

2. In application.properties:-

# Provider AdminClient --Admin server URL
spring.boot.admin.client.url=http://localhost:9988

#management.endpoints.web.base-path=/
#management.endpoints.web.base-path=/mytest
#management.endpoints.web.exposure.exclude=health,info,beans,env
#management.endpoint.health.show-details=always
#management.endpoint.health.show-details=when-authorized
#management.endpoint.health.enabled=false
#management.endpoint.info.enabled=false
info.app.title=ABCD-APP
info.app.version=3.2 GA
info.client.name=KnowProgram
info.client.license=KnowProgram-NEW
management.endpoints.web.exposure.include=*

3. RestController:-

package com.knowprogram.demo.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
@RequestMapping("/employee")
public class EmployeeRestController {

    @Autowired
    private RestTemplate rt;

    @GetMapping("/show")
    public ResponseEntity<String> showMsg() {
        return ResponseEntity.ok("Hello");
    }
}

4. AppConfig:-

package com.knowprogram.demo.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class AppConfig {
    @Bean
    RestTemplate rtemplate() {
        return new RestTemplate();
    }
}

Run Apps

1. Admin Server
2. Microservice app
3. Enter URL:- http://localhost:9988/applications
4. Click on the Application name

5. Click on the ID shown
6. Check all services

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