Add log message when application is ready (#665)

* Add log message when application is ready

This marks the moment the application is ready more clearly now
that there are 2 'Started Launcher' log messages.

Additionally, this is somewhat helpful for people running LL through
subprocess that want to programmatically detect when application starts
to accept connections.

* Change "Application" to "Lavalink"

Co-authored-by: Freya Arbjerg <[email protected]>

Author: Jackenmen

LavalinkServer/src/main/java/lavalink/server/Launcher.kt

@@ -34,6 +34,7 @@ import org.springframework.boot.autoconfigure.SpringBootApplication
 import org.springframework.boot.builder.SpringApplicationBuilder
 import org.springframework.boot.context.event.ApplicationEnvironmentPreparedEvent
 import org.springframework.boot.context.event.ApplicationFailedEvent
+import org.springframework.boot.context.event.ApplicationReadyEvent
 import org.springframework.context.ApplicationListener
 import org.springframework.context.ConfigurableApplicationContext
 import org.springframework.context.annotation.ComponentScan
@@ -150,6 +151,11 @@ object Launcher {
                         log.info(getVersionInfo())
                     }
                 },
+                ApplicationListener { event: Any ->
+                    if (event is ApplicationReadyEvent) {
+                        log.info("Lavalink is ready to accept connections.")
+                    }
+                },
                 ApplicationListener { event: Any ->
                     if (event is ApplicationFailedEvent) {
                         log.error("Application failed", event.exception)