org.springframework.boot.context.embedded.LocalServerPort

In a Spring Boot application, org.springframework.boot.context.embedded.LocalServerPort is an annotation that enables you to bind the application to a randomly available port at runtime.

Syntax

@Value("${local.server.port}")
private int port;

Description

org.springframework.boot.context.embedded.LocalServerPort can be used to retrieve the port number the application is currently running on. When this annotation is used, Spring Boot binds the application to a port that is determined by the operating system at runtime. This provides flexibility, as the application can be assigned any available port at runtime.

The @Value annotation is used to inject the property value into the field. The ${local.server.port} placeholder is automatically resolved by Spring Boot at runtime.

Example

@RestController
public class PortController {
 
    @Value("${local.server.port}")
    private int port;
 
    @GetMapping("/port")
    public String getPort() {
        return "Application is running on port " + port;
    }
}

In the example code snippet above, a REST endpoint is exposed to return the port the application is currently running on. When this endpoint is accessed, the value extracted from the @Value annotation is returned as a string.

Conclusion

org.springframework.boot.context.embedded.LocalServerPort is a useful annotation in Spring Boot applications that enables you to bind your application to a randomly available port at runtime. This makes your application flexible and easily deployable by other services.