java - How to get local server host and port in Spring Boot?

Question

I'm starting up a Spring Boot application with mvn spring-boot:run.

One of my @Controllers needs information about the host and port the application is listening on, i.e. localhost:8080 (or 127.x.y.z:8080). Following the Spring Boot documentation, I use the server.address and server.port properties:

@Controller
public class MyController {

    @Value("${server.address}")
    private String serverAddress;

    @Value("${server.port}")
    private String serverPort;

    //...

}

When starting up the application with mvn spring-boot:run, I get the following exception:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myController': Injection of autowired dependencies failed; nested exception is 
org.springframework.beans.factory.BeanCreationException: Could not autowire field: ... String ... serverAddress; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'server.address' in string value "${server.address}"

Both server.address and server.port cannot be autowired.

How can I find out the (local) host/address/NIC and port that a Spring Boot application is binding on?

Answer 1

IP Address

You can get network interfaces with NetworkInterface.getNetworkInterfaces(), then the IP addresses off the NetworkInterface objects returned with .getInetAddresses(), then the string representation of those addresses with .getHostAddress().

Port

If you make a @Configuration class which implements ApplicationListener<EmbeddedServletContainerInitializedEvent>, you can override onApplicationEvent to get the port number once it's set.

@Override
public void onApplicationEvent(EmbeddedServletContainerInitializedEvent event) {
    int port = event.getEmbeddedServletContainer().getPort();
}