Improve exception handling when configuring and starting the Minecraft server

Agent/Phantom.Agent.Minecraft/Launcher/BaseLauncher.cs

@@ -5,6 +5,7 @@ using Phantom.Agent.Minecraft.Instance;
 using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Server;
 using Phantom.Common.Minecraft;
+using Serilog;
 
 namespace Phantom.Agent.Minecraft.Launcher;
 
@@ -15,7 +16,7 @@ public abstract class BaseLauncher {
 		this.instanceProperties = instanceProperties;
 	}
 
-	public async Task<LaunchResult> Launch(LaunchServices services, EventHandler<DownloadProgressEventArgs> downloadProgressEventHandler, CancellationToken cancellationToken) {
+	public async Task<LaunchResult> Launch(ILogger logger, LaunchServices services, EventHandler<DownloadProgressEventArgs> downloadProgressEventHandler, CancellationToken cancellationToken) {
 		if (!services.JavaRuntimeRepository.TryGetByGuid(instanceProperties.JavaRuntimeGuid, out var javaRuntimeExecutable)) {
 			return new LaunchResult.InvalidJavaRuntime();
 		}
@@ -52,12 +53,29 @@ public abstract class BaseLauncher {
 		var process = new Process { StartInfo = startInfo };
 		var session = new InstanceSession(process);
 
-		await AcceptEula(instanceProperties);
+		try {
-		await UpdateServerProperties(instanceProperties);
+			await AcceptEula(instanceProperties);
+			await UpdateServerProperties(instanceProperties);
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while configuring the server.");
+			return new LaunchResult.CouldNotConfigureMinecraftServer();
+		}
 
-		process.Start();
+		try {
-		process.BeginOutputReadLine();
+			process.Start();
-		process.BeginErrorReadLine();
+			process.BeginOutputReadLine();
+			process.BeginErrorReadLine();
+		} catch (Exception launchException) {
+			logger.Error(launchException, "Caught exception launching the server process.");
+			
+			try {
+				process.Kill();
+			} catch (Exception killException) {
+				logger.Error(killException, "Caught exception trying to kill the server process after a failed launch.");
+			}
+
+			return new LaunchResult.CouldNotStartMinecraftServer();
+		}
 
 		return new LaunchResult.Success(session);
 	}
@@ -80,8 +98,8 @@ public abstract class BaseLauncher {
 		await using var fileStream = new FileStream(serverPropertiesFilePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
 		try {
 			serverPropertiesData.Load(fileStream);
-		} catch (ParseException) {
+		} catch (ParseException e) {
-			// ignore
+			throw new Exception("Could not parse server.properties file: " + serverPropertiesFilePath, e);
 		}
 		
 		instanceProperties.ServerProperties.SetTo(serverPropertiesData);

Agent/Phantom.Agent.Minecraft/Launcher/LaunchResult.cs

@@ -12,4 +12,8 @@ public abstract record LaunchResult {
 	public sealed record InvalidJvmArguments : LaunchResult;
 
 	public sealed record CouldNotDownloadMinecraftServer : LaunchResult;
+	
+	public sealed record CouldNotConfigureMinecraftServer : LaunchResult;
+	
+	public sealed record CouldNotStartMinecraftServer : LaunchResult;
 }

Agent/Phantom.Agent.Services/Instances/States/InstanceLaunchingState.cs

@@ -37,7 +37,7 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 			}
 		}
 
-		var launchResult = await context.Launcher.Launch(context.LaunchServices, OnDownloadProgress, cancellationToken);
+		var launchResult = await context.Launcher.Launch(context.Logger, context.LaunchServices, OnDownloadProgress, cancellationToken);
 		if (launchResult is LaunchResult.InvalidJavaRuntime) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.JavaRuntimeNotFound, "Session failed to launch, invalid Java runtime.");
 		}
@@ -47,6 +47,12 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 		else if (launchResult is LaunchResult.CouldNotDownloadMinecraftServer) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotDownloadMinecraftServer, "Session failed to launch, could not download Minecraft server.");
 		}
+		else if (launchResult is LaunchResult.CouldNotConfigureMinecraftServer) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotConfigureMinecraftServer, "Session failed to launch, could not configure Minecraft server.");
+		}
+		else if (launchResult is LaunchResult.CouldNotStartMinecraftServer) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotStartMinecraftServer, "Session failed to launch, could not start Minecraft server.");
+		}
 
 		if (launchResult is not LaunchResult.Success launchSuccess) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.UnknownError, "Session failed to launch.");

Common/Phantom.Common.Data/Instance/InstanceLaunchFailReason.cs

@@ -8,20 +8,24 @@ public enum InstanceLaunchFailReason {
 	RconPortAlreadyInUse,
 	JavaRuntimeNotFound,
 	InvalidJvmArguments,
-	CouldNotDownloadMinecraftServer
+	CouldNotDownloadMinecraftServer,
+	CouldNotConfigureMinecraftServer,
+	CouldNotStartMinecraftServer
 }
 
 public static class InstanceLaunchFailReasonExtensions {
 	public static string ToSentence(this InstanceLaunchFailReason reason) {
 		return reason switch {
-			InstanceLaunchFailReason.ServerPortNotAllowed            => "Server port not allowed.",
+			InstanceLaunchFailReason.ServerPortNotAllowed             => "Server port not allowed.",
-			InstanceLaunchFailReason.ServerPortAlreadyInUse          => "Server port already in use.",
+			InstanceLaunchFailReason.ServerPortAlreadyInUse           => "Server port already in use.",
-			InstanceLaunchFailReason.RconPortNotAllowed              => "Rcon port not allowed.",
+			InstanceLaunchFailReason.RconPortNotAllowed               => "Rcon port not allowed.",
-			InstanceLaunchFailReason.RconPortAlreadyInUse            => "Rcon port already in use.",
+			InstanceLaunchFailReason.RconPortAlreadyInUse             => "Rcon port already in use.",
-			InstanceLaunchFailReason.JavaRuntimeNotFound             => "Java runtime not found.",
+			InstanceLaunchFailReason.JavaRuntimeNotFound              => "Java runtime not found.",
-			InstanceLaunchFailReason.InvalidJvmArguments             => "Invalid JVM arguments.",
+			InstanceLaunchFailReason.InvalidJvmArguments              => "Invalid JVM arguments.",
-			InstanceLaunchFailReason.CouldNotDownloadMinecraftServer => "Could not download Minecraft server.",
+			InstanceLaunchFailReason.CouldNotDownloadMinecraftServer  => "Could not download Minecraft server.",
-			_                                                        => "Unknown error."
+			InstanceLaunchFailReason.CouldNotConfigureMinecraftServer => "Could not configure Minecraft server.",
+			InstanceLaunchFailReason.CouldNotStartMinecraftServer     => "Could not start Minecraft server.",
+			_                                                         => "Unknown error."
 		};
 	}
 }