Spring Boot Actuator: Hello World Application

Step 1: Create basic Skelton project.

Go to 'https://start.spring.io/' and give the Group as 'com.sample', Artifact as 'app' and add below dependencies.

a.   Spring Web Starter

b.   H2 Database

c.    Spring Data JPA

d.   Spring Boot Actuator

e.   Spring Boot DevTools

Click on the button ‘Generate the project’.

Extract the downloaded zip file.

Step 2: Export the project to Eclipse.

Open Eclipse.

File -> Import.

Search for maven.

Select ‘Existing Maven Projects’. Click on Next button.

Browse to the location where you extracted the zip file, click on Finish button.

Imported project looks like below.

Step 2: Create a package ‘com.sample.app.controller’ and define HelloController.

HelloController.java

package com.sample.app.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

 @RequestMapping("/")
 public String home() {
  return "Welcome to spring boot developement";
 }

}

AppApplication.java

package com.sample.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class AppApplication {

 public static void main(String[] args) {
  SpringApplication.run(AppApplication.class, args);
 }

}

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>
 <parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>2.1.7.RELEASE</version>
  <relativePath/> <!-- lookup parent from repository -->
 </parent>
 <groupId>com.sample</groupId>
 <artifactId>app</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <name>app</name>
 <description>Demo project for Spring Boot</description>

 <properties>
  <java.version>1.8</java.version>
 </properties>

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

  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-devtools</artifactId>
   <scope>runtime</scope>
   <optional>true</optional>
  </dependency>
  <dependency>
   <groupId>com.h2database</groupId>
   <artifactId>h2</artifactId>
   <scope>runtime</scope>
  </dependency>
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-test</artifactId>
   <scope>test</scope>
  </dependency>
 </dependencies>

 <build>
  <plugins>
   <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
   </plugin>
  </plugins>
 </build>

</project>

Run AppApplication.java.

Open the url ‘http://localhost:8080/actuator’ in browser, you can see below kind of response.

{
  "_links": {
    "self": {
      "href": "http://localhost:8080/actuator",
      "templated": false
    },
    "health": {
      "href": "http://localhost:8080/actuator/health",
      "templated": false
    },
    "health-component": {
      "href": "http://localhost:8080/actuator/health/{component}",
      "templated": true
    },
    "health-component-instance": {
      "href": "http://localhost:8080/actuator/health/{component}/{instance}",
      "templated": true
    },
    "info": {
      "href": "http://localhost:8080/actuator/info",
      "templated": false
    }
  }
}

Adding security to the application

Add spring security Starter dependency.

<dependency>

  <groupId>org.springframework.boot</groupId>

  <artifactId>spring-boot-starter-security</artifactId>

</dependency>

Add below properties to application.properties file.

application.properties

spring.security.user.name=krishna
spring.security.user.password=password123
spring.security.user.roles = ["USER", "ADMIN"]

Stop and restart the application.

Open the url 'http://localhost:8080/actuator' in browser, you will be navigated to login page.    

Enter username as krishna and password as password123 and click on Sign in button. You will be navigated to actuator screen.

You can download the complete working application from this link.

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