Force Spring Boot application to use a config file.

Main.java

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication
public class Main {
	private static final String CONFIG_NAME = "myapp";  // FIXME - this will read configs from file myapp.properties; fix as required

	private static final Class<?> mainClass = Main.class; // FIXME - adapt to the class containing method main(String[]) in your app.
	

	public static void main(String[] args) {
		/*
		 * Ugly hack.
		 * Ideally, this config should be found in the env variable, SPRING_CONFIG_NAME.
		 * However, I'm having a lot of trouble to get env vars to work in the linux box where
		 *  this app is deployed.
		 * So I'm artificially forcing it here, as if it were a command line argument.
		 * 
		 * See: https://docs.spring.io/spring-boot/docs/1.5.10.RELEASE/reference/htmlsingle/#boot-features-external-config-application-property-files
		 */
		args = includeConfigName(args, CONFIG_NAME);
		SpringApplication.run(mainClass, args);
	}

	private static String[] includeConfigName(String[] args, String configName) {
		String arg = "--spring.config.name";
		for (String a: args) {
			if (a.startsWith(arg)) {
				/*
				 * Argument was supplied, use it as supplied.
				 */
				System.out.println("Using config from command line argument: " + a);
				return args;
			}
		}
		
		/*
		 * Forcefully include an arg into the command line.
		 */
		String args2[] = new String[args.length + 1];
		System.arraycopy(args, 0, args2, 0, args.length);
		String newArg = arg + "=" + configName;
		args2[args2.length - 1] = newArg;
		System.out.println("Force config: " + newArg);
		return args2;
	}
}