src/main/java/
  └── com/example/demo/
        ├── DemoApplication.java
        ├── controller/
        ├── service/
        └── repository/

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

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    private final UserService userService;
    
    public UserController(UserService userService) {
        this.userService = userService;
    }
    
    @GetMapping
    public List<User> getAllUsers() {
        return userService.findAll();
    }
    
    @GetMapping("/{id}")
    public User getUserById(@PathVariable Long id) {
        return userService.findById(id);
    }
    
    @PostMapping
    @ResponseStatus(HttpStatus.CREATED)
    public User createUser(@RequestBody User user) {
        return userService.create(user);
    }
}

<!-- В pom.xml -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</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-test</artifactId>
    <scope>test</scope>
</dependency>

# application.yml
server:
  port: 8081
  
spring:
  datasource:
    url: jdbc:postgresql://localhost:5432/mydb
    username: user
    password: pass
  
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true

# Мониторинг приложения
management:
  endpoints:
    web:
      exposure:
        include: health,info,metrics