Improve run configs (#318) (#338)

Co-authored-by: ShadewRG <onankman@gmail.com>
Co-authored-by: UndeadCat | Shadew <redgalaxysw@gmail.com>
Co-authored-by: liach <7806504+liach@users.noreply.github.com>

build.gradle

@@ -106,7 +106,7 @@ license {
 
 checkstyle {
 	configFile = file('checkstyle.xml')
-	toolVersion = '8.25'
+	toolVersion = '8.39'
 }
 
 checkstyleMain {

src/main/java/net/fabricmc/loom/LoomGradleExtension.java

@@ -41,15 +41,19 @@ import java.util.stream.Collectors;
 import com.google.gson.JsonObject;
 import org.cadixdev.lorenz.MappingSet;
 import org.cadixdev.mercury.Mercury;
+import org.gradle.api.Action;
+import org.gradle.api.NamedDomainObjectContainer;
 import org.gradle.api.Project;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.Dependency;
 import org.gradle.api.file.ConfigurableFileCollection;
 import org.gradle.api.plugins.BasePluginConvention;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.Nullable;
 
 import net.fabricmc.loom.api.decompilers.LoomDecompiler;
 import net.fabricmc.loom.configuration.LoomDependencyManager;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
 import net.fabricmc.loom.configuration.processors.JarProcessor;
 import net.fabricmc.loom.configuration.processors.JarProcessorManager;
 import net.fabricmc.loom.configuration.providers.MinecraftProvider;
@@ -58,7 +62,6 @@ import net.fabricmc.loom.configuration.providers.mappings.MojangMappingsDependen
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftMappedProvider;
 
 public class LoomGradleExtension {
-	public String runDir = "run";
 	public String refmapName;
 	public String loaderLaunchMethod;
 	public boolean remapMod = true;
@@ -82,6 +85,8 @@ public class LoomGradleExtension {
 	private Mercury[] srcMercuryCache = new Mercury[2];
 	private Set<File> mixinMappings = Collections.synchronizedSet(new HashSet<>());
 
+	private NamedDomainObjectContainer<RunConfigSettings> runs;
+
 	/**
 	 * Loom will generate a new genSources task (with a new name, based off of {@link LoomDecompiler#name()})
 	 * that uses the specified decompiler instead.
@@ -117,6 +122,8 @@ public class LoomGradleExtension {
 		this.project = project;
 		this.autoGenIDERuns = isRootProject();
 		this.unmappedMods = project.files();
+		this.runs = project.container(RunConfigSettings.class,
+				baseName -> new RunConfigSettings(project, baseName));
 	}
 
 	/**
@@ -134,8 +141,8 @@ public class LoomGradleExtension {
 	@Deprecated
 	public List<Path> getUnmappedMods() {
 		return unmappedMods.getFiles().stream()
-			.map(File::toPath)
+				.map(File::toPath)
-			.collect(Collectors.toList());
+				.collect(Collectors.toList());
 	}
 
 	public ConfigurableFileCollection getUnmappedModCollection() {
@@ -292,7 +299,7 @@ public class LoomGradleExtension {
 
 	@Nullable
 	private Dependency getMixinDependency() {
-		return recurseProjects((p) -> {
+		return recurseProjects(p -> {
 			List<Configuration> configs = new ArrayList<>();
 			// check compile classpath first
 			Configuration possibleCompileClasspath = p.getConfigurations().findByName("compileClasspath");
@@ -309,11 +316,7 @@ public class LoomGradleExtension {
 					return true;
 				}
 
-				if (name.equalsIgnoreCase("sponge-mixin") && group.equalsIgnoreCase("net.fabricmc")) {
+				return name.equalsIgnoreCase("sponge-mixin") && group.equalsIgnoreCase("net.fabricmc");
-					return true;
-				}
-
-				return false;
 			});
 		});
 	}
@@ -426,4 +429,14 @@ public class LoomGradleExtension {
 	public List<LoomDecompiler> getDecompilers() {
 		return decompilers;
 	}
+
+	@ApiStatus.Experimental
+	public void runs(Action<NamedDomainObjectContainer<RunConfigSettings>> action) {
+		action.execute(runs);
+	}
+
+	@ApiStatus.Experimental
+	public NamedDomainObjectContainer<RunConfigSettings> getRuns() {
+		return runs;
+	}
 }

src/main/java/net/fabricmc/loom/configuration/ide/RunConfig.java

@@ -24,12 +24,10 @@
 
 package net.fabricmc.loom.configuration.ide;
 
-import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
-import java.util.Locale;
 import java.util.Map;
 
 import com.google.common.base.Strings;
@@ -37,9 +35,9 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
-import org.apache.commons.io.FileUtils;
 import org.apache.commons.io.IOUtils;
 import org.gradle.api.Project;
+import org.gradle.api.tasks.SourceSet;
 import org.gradle.plugins.ide.eclipse.model.EclipseModel;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
@@ -54,6 +52,7 @@ public class RunConfig {
 	public String eclipseProjectName;
 	public String ideaModuleName;
 	public String mainClass;
+	public String runDirIdeaUrl;
 	public String runDir;
 	public String vmArgs;
 	public String programArgs;
@@ -64,7 +63,7 @@ public class RunConfig {
 
 		this.addXml(root, "module", ImmutableMap.of("name", ideaModuleName));
 		this.addXml(root, "option", ImmutableMap.of("name", "MAIN_CLASS_NAME", "value", mainClass));
-		this.addXml(root, "option", ImmutableMap.of("name", "WORKING_DIRECTORY", "value", runDir));
+		this.addXml(root, "option", ImmutableMap.of("name", "WORKING_DIRECTORY", "value", runDirIdeaUrl));
 
 		if (!Strings.isNullOrEmpty(vmArgs)) {
 			this.addXml(root, "option", ImmutableMap.of("name", "VM_PARAMETERS", "value", vmArgs));
@@ -94,8 +93,8 @@ public class RunConfig {
 		return e;
 	}
 
-	private static String getIdeaModuleName(Project project) {
+	private static String getIdeaModuleName(Project project, SourceSet srcs) {
-		String module = project.getName() + ".main";
+		String module = project.getName() + "." + srcs.getName();
 
 		while ((project = project.getParent()) != null) {
 			module = project.getName() + "." + module;
@@ -107,12 +106,11 @@ public class RunConfig {
 	private static void populate(Project project, LoomGradleExtension extension, RunConfig runConfig, String mode) {
 		runConfig.configName += extension.isRootProject() ? "" : " (" + project.getPath() + ")";
 		runConfig.eclipseProjectName = project.getExtensions().getByType(EclipseModel.class).getProject().getName();
-		runConfig.ideaModuleName = getIdeaModuleName(project);
-		runConfig.runDir = "file://$PROJECT_DIR$/" + extension.runDir;
 		runConfig.vmArgs = "";
+		runConfig.programArgs = "";
 
 		if ("launchwrapper".equals(extension.getLoaderLaunchMethod())) {
-			runConfig.mainClass = "net.minecraft.launchwrapper.Launch";
+			runConfig.mainClass = "net.minecraft.launchwrapper.Launch"; // TODO What about custom tweakers for run configs?
 			runConfig.programArgs += "--tweakClass " + ("client".equals(mode) ? Constants.LaunchWrapper.DEFAULT_FABRIC_CLIENT_TWEAKER : Constants.LaunchWrapper.DEFAULT_FABRIC_SERVER_TWEAKER);
 		} else {
 			runConfig.mainClass = "net.fabricmc.devlaunchinjector.Main";
@@ -149,35 +147,74 @@ public class RunConfig {
 		}
 	}
 
-	public static RunConfig clientRunConfig(Project project) {
+	// Turns camelCase/PascalCase into Capital Case
-		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+	// caseConversionExample -> Case Conversion Example
+	private static String capitalizeCamelCaseName(String name) {
+		if (name.length() == 0) {
+			return "";
+		}
 
-		RunConfig ideaClient = new RunConfig();
+		return name.substring(0, 1).toUpperCase() + name.substring(1).replaceAll("([^A-Z])([A-Z])", "$1 $2");
-		ideaClient.configName = "Minecraft Client";
-		ideaClient.programArgs = "";
-		populate(project, extension, ideaClient, "client");
-		ideaClient.vmArgs += getOSClientJVMArgs();
-		ideaClient.vmArgs += " -Dfabric.dli.main=" + getMainClass("client", extension);
-
-		return ideaClient;
 	}
 
-	public static RunConfig serverRunConfig(Project project) {
+	public static RunConfig runConfig(Project project, RunConfigSettings settings) {
 		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		String name = settings.getName();
 
-		RunConfig ideaServer = new RunConfig();
+		String configName = settings.getConfigName();
-		ideaServer.configName = "Minecraft Server";
+		String mode = settings.getMode();
-		ideaServer.programArgs = "nogui ";
+		SourceSet sourceSet = settings.getSource(project);
-		populate(project, extension, ideaServer, "server");
-		ideaServer.vmArgs += " -Dfabric.dli.main=" + getMainClass("server", extension);
 
-		return ideaServer;
+		String defaultMain = settings.getDefaultMainClass();
-	}
 
-	// This can be removed at somepoint, its not ideal but its the best solution I could thing of
+		if (defaultMain == null) {
-	public static boolean needsUpgrade(File file) throws IOException {
+			throw new IllegalArgumentException("Run configuration '" + name + "' must specify 'defaultMainClass'");
-		String contents = FileUtils.readFileToString(file, StandardCharsets.UTF_8);
+		}
-		return !(contents.contains("net.fabricmc.devlaunchinjector.Main"));
+
+		if (configName == null) {
+			configName = "";
+			String srcName = sourceSet.getName();
+
+			if (!srcName.equals(SourceSet.MAIN_SOURCE_SET_NAME)) {
+				configName += capitalizeCamelCaseName(srcName) + " ";
+			}
+
+			configName += "Minecraft " + capitalizeCamelCaseName(name);
+		}
+
+		if (mode == null) {
+			mode = name;
+		}
+
+		String runDir = settings.getRunDir();
+
+		if (runDir == null) {
+			runDir = "run";
+		}
+
+		RunConfig runConfig = new RunConfig();
+		runConfig.configName = configName;
+		populate(project, extension, runConfig, mode);
+		runConfig.ideaModuleName = getIdeaModuleName(project, sourceSet);
+		runConfig.runDirIdeaUrl = "file://$PROJECT_DIR$/" + runDir;
+		runConfig.runDir = runDir;
+
+		// Custom parameters
+		for (String progArg : settings.getProgramArgs()) {
+			runConfig.programArgs += " " + progArg;
+		}
+
+		for (String vmArg : settings.getVmArgs()) {
+			runConfig.vmArgs += " " + vmArg;
+		}
+
+		runConfig.vmArgs += " -Dfabric.dli.main=" + getMainClass(mode, extension, defaultMain);
+
+		// Remove unnecessary leading/trailing whitespaces we might have generated
+		runConfig.programArgs = runConfig.programArgs.trim();
+		runConfig.vmArgs = runConfig.vmArgs.trim();
+
+		return runConfig;
 	}
 
 	public String fromDummy(String dummy) throws IOException {
@@ -191,6 +228,7 @@ public class RunConfig {
 		dummyConfig = dummyConfig.replace("%MAIN_CLASS%", mainClass);
 		dummyConfig = dummyConfig.replace("%ECLIPSE_PROJECT%", eclipseProjectName);
 		dummyConfig = dummyConfig.replace("%IDEA_MODULE%", ideaModuleName);
+		dummyConfig = dummyConfig.replace("%RUN_DIRECTORY%", runDir);
 		dummyConfig = dummyConfig.replace("%PROGRAM_ARGS%", programArgs.replaceAll("\"", """));
 		dummyConfig = dummyConfig.replace("%VM_ARGS%", vmArgs.replaceAll("\"", """));
 
@@ -205,7 +243,7 @@ public class RunConfig {
 		return "";
 	}
 
-	private static String getMainClass(String side, LoomGradleExtension extension) {
+	private static String getMainClass(String side, LoomGradleExtension extension, String defaultMainClass) {
 		JsonObject installerJson = extension.getInstallerJson();
 
 		if (installerJson != null && installerJson.has("mainClass")) {
@@ -231,7 +269,7 @@ public class RunConfig {
 			return "net.minecraft.launchwrapper.Launch";
 		}
 
-		return "net.fabricmc.loader.launch.knot.Knot" + side.substring(0, 1).toUpperCase(Locale.ROOT) + side.substring(1).toLowerCase(Locale.ROOT);
+		return defaultMainClass;
 	}
 
 	private static String encodeEscaped(String s) {

src/main/java/net/fabricmc/loom/configuration/ide/RunConfigSettings.java

@@ -0,0 +1,291 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.configuration.ide;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+
+import org.gradle.api.Named;
+import org.gradle.api.Project;
+import org.gradle.api.plugins.JavaPluginConvention;
+import org.gradle.api.tasks.SourceSet;
+import org.jetbrains.annotations.ApiStatus;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.OperatingSystem;
+
+/**
+ * Experimental for now, please make sure to direct any suggests towards the github.
+ */
+@ApiStatus.Experimental
+public final class RunConfigSettings implements Named {
+	/**
+	 * Arguments for the JVM, such as system properties.
+	 */
+	private final List<String> vmArgs = new ArrayList<>();
+
+	/**
+	 * Arguments for the program's main class.
+	 */
+	private final List<String> programArgs = new ArrayList<>();
+
+	/**
+	 * The mode to run, which is the name of the run config in {@code fabric_installer.[method].json}.
+	 */
+	private String mode;
+
+	/**
+	 * The full name of the run configuration, i.e. 'Minecraft Client'.
+	 *
+	 * <p>By default this is determined from the base name.
+	 */
+	private String name;
+
+	/**
+	 * The default main class of the run configuration.
+	 *
+	 * <p>This can be overwritten in {@code fabric_installer.[method].json}. Note that this <em>doesn't</em> take
+	 * priority over the main class specified in the Fabric installer configuration.
+	 */
+	private String defaultMainClass;
+
+	/**
+	 * The source set getter, which obtains the source set from the given project.
+	 */
+	private Function<Project, SourceSet> source;
+
+	/**
+	 * The run directory for this configuration, relative to the root project directory.
+	 */
+	private String runDir;
+
+	/**
+	 * The base name of the run configuration, which is the name it is created with, i.e. 'client'
+	 */
+	private final String baseName;
+
+	private final Project project;
+	private final LoomGradleExtension extension;
+
+	public RunConfigSettings(Project project, String baseName) {
+		this.baseName = baseName;
+		this.project = project;
+		this.extension = project.getExtensions().getByType(LoomGradleExtension.class);
+
+		mode(baseName);
+		source("main");
+		runDir("run");
+	}
+
+	public Project getProject() {
+		return project;
+	}
+
+	public LoomGradleExtension getExtension() {
+		return extension;
+	}
+
+	@Override
+	public String getName() {
+		return baseName;
+	}
+
+	public List<String> getVmArgs() {
+		return vmArgs;
+	}
+
+	public List<String> getProgramArgs() {
+		return programArgs;
+	}
+
+	public String getMode() {
+		return mode;
+	}
+
+	public void setMode(String mode) {
+		this.mode = mode;
+	}
+
+	public String getConfigName() {
+		return name;
+	}
+
+	public void setConfigName(String name) {
+		this.name = name;
+	}
+
+	public String getDefaultMainClass() {
+		return defaultMainClass;
+	}
+
+	public void setDefaultMainClass(String defaultMainClass) {
+		this.defaultMainClass = defaultMainClass;
+	}
+
+	public String getRunDir() {
+		return runDir;
+	}
+
+	public void setRunDir(String runDir) {
+		this.runDir = runDir;
+	}
+
+	public SourceSet getSource(Project proj) {
+		return source.apply(proj);
+	}
+
+	public void setSource(SourceSet source) {
+		this.source = proj -> source;
+	}
+
+	public void setSource(Function<Project, SourceSet> sourceFn) {
+		this.source = sourceFn;
+	}
+
+	public void mode(String mode) {
+		setMode(mode);
+	}
+
+	public void name(String name) {
+		setConfigName(name);
+	}
+
+	public void defaultMainClass(String cls) {
+		setDefaultMainClass(cls);
+	}
+
+	public void runDir(String dir) {
+		setRunDir(dir);
+	}
+
+	public void vmArg(String arg) {
+		vmArgs.add(arg);
+	}
+
+	public void vmArgs(String... args) {
+		vmArgs.addAll(Arrays.asList(args));
+	}
+
+	public void vmArgs(Collection<String> args) {
+		vmArgs.addAll(args);
+	}
+
+	public void property(String name, String value) {
+		vmArg("-D" + name + "=" + value);
+	}
+
+	public void property(String name) {
+		vmArg("-D" + name);
+	}
+
+	public void properties(Map<String, String> props) {
+		props.forEach(this::property);
+	}
+
+	public void programArg(String arg) {
+		programArgs.add(arg);
+	}
+
+	public void programArgs(String... args) {
+		programArgs.addAll(Arrays.asList(args));
+	}
+
+	public void programArgs(Collection<String> args) {
+		programArgs.addAll(args);
+	}
+
+	public void source(SourceSet source) {
+		setSource(source);
+	}
+
+	public void source(String source) {
+		setSource(proj -> {
+			JavaPluginConvention conv = proj.getConvention().getPlugin(JavaPluginConvention.class);
+			return conv.getSourceSets().getByName(source);
+		});
+	}
+
+	/**
+	 * Add the {@code -XstartOnFirstThread} JVM argument when on OSX.
+	 */
+	public void startFirstThread() {
+		if (OperatingSystem.getOS().equalsIgnoreCase("osx")) {
+			vmArg("-XstartOnFirstThread");
+		}
+	}
+
+	/**
+	 * Removes the {@code nogui} argument for the server configuration. By default {@code nogui} is specified, this is
+	 * a convenient way to remove it if wanted.
+	 */
+	public void serverWithGui() {
+		programArgs.removeIf("nogui"::equals);
+	}
+
+	/**
+	 * Configure run config with the default client options.
+	 */
+	public void client() {
+		startFirstThread();
+		mode("client");
+		defaultMainClass(Constants.Knot.KNOT_CLIENT);
+	}
+
+	/**
+	 * Configure run config with the default server options.
+	 */
+	public void server() {
+		programArg("nogui");
+		mode("server");
+		defaultMainClass(Constants.Knot.KNOT_SERVER);
+	}
+
+	/**
+	 * Copies settings from another run configuration.
+	 */
+	public void inherit(RunConfigSettings parent) {
+		vmArgs.addAll(0, parent.vmArgs);
+		programArgs.addAll(0, parent.programArgs);
+
+		mode = parent.mode;
+		name = parent.name;
+		defaultMainClass = parent.defaultMainClass;
+		source = parent.source;
+	}
+
+	public void makeRunDir() {
+		File file = new File(getProject().getRootDir(), runDir);
+
+		if (!file.exists()) {
+			file.mkdir();
+		}
+	}
+}

src/main/java/net/fabricmc/loom/configuration/ide/SetupIntelijRunConfigs.java

@@ -50,12 +50,6 @@ public class SetupIntelijRunConfigs {
 		} catch (IOException e) {
 			throw new RuntimeException("Failed to generate run configs", e);
 		}
-
-		File runDir = new File(project.getRootDir(), extension.runDir);
-
-		if (!runDir.exists()) {
-			runDir.mkdirs();
-		}
 	}
 
 	private static void generate(Project project) throws IOException {
@@ -72,22 +66,23 @@ public class SetupIntelijRunConfigs {
 
 		File projectDir = rootProject.file(".idea");
 		File runConfigsDir = new File(projectDir, "runConfigurations");
-		File clientRunConfigs = new File(runConfigsDir, "Minecraft_Client" + projectPath + ".xml");
-		File serverRunConfigs = new File(runConfigsDir, "Minecraft_Server" + projectPath + ".xml");
 
 		if (!runConfigsDir.exists()) {
 			runConfigsDir.mkdirs();
 		}
 
-		String clientRunConfig = RunConfig.clientRunConfig(project).fromDummy("idea_run_config_template.xml");
+		for (RunConfigSettings settings : extension.getRuns()) {
-		String serverRunConfig = RunConfig.serverRunConfig(project).fromDummy("idea_run_config_template.xml");
+			RunConfig config = RunConfig.runConfig(project, settings);
+			String name = config.configName.replaceAll("[^a-zA-Z0-9$_]", "_");
 
-		if (!clientRunConfigs.exists() || RunConfig.needsUpgrade(clientRunConfigs)) {
+			File runConfigs = new File(runConfigsDir, name + projectPath + ".xml");
-			FileUtils.writeStringToFile(clientRunConfigs, clientRunConfig, StandardCharsets.UTF_8);
+			String runConfigXml = config.fromDummy("idea_run_config_template.xml");
-		}
 
-		if (!serverRunConfigs.exists() || RunConfig.needsUpgrade(serverRunConfigs)) {
+			if (!runConfigs.exists()) {
-			FileUtils.writeStringToFile(serverRunConfigs, serverRunConfig, StandardCharsets.UTF_8);
+				FileUtils.writeStringToFile(runConfigs, runConfigXml, StandardCharsets.UTF_8);
+			}
+
+			settings.makeRunDir();
 		}
 	}
 }

src/main/java/net/fabricmc/loom/task/AbstractRunTask.java

@@ -85,8 +85,7 @@ public abstract class AbstractRunTask extends JavaExec {
 		}
 
 		args(argsSplit);
-		LoomGradleExtension extension = this.getProject().getExtensions().getByType(LoomGradleExtension.class);
+		setWorkingDir(new File(getProject().getRootDir(), config.runDir));
-		setWorkingDir(new File(getProject().getRootDir(), extension.runDir));
 
 		super.exec();
 	}

src/main/java/net/fabricmc/loom/task/GenEclipseRunsTask.java

@@ -32,30 +32,28 @@ import org.apache.commons.io.FileUtils;
 import org.gradle.api.tasks.TaskAction;
 import org.gradle.plugins.ide.eclipse.model.EclipseModel;
 
+import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.RunConfig;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
 
 public class GenEclipseRunsTask extends AbstractLoomTask {
 	@TaskAction
 	public void genRuns() throws IOException {
 		EclipseModel eclipseModel = getProject().getExtensions().getByType(EclipseModel.class);
-		File clientRunConfigs = new File(getProject().getRootDir(), eclipseModel.getProject().getName() + "_client.launch");
+		LoomGradleExtension extension = getExtension();
-		File serverRunConfigs = new File(getProject().getRootDir(), eclipseModel.getProject().getName() + "_server.launch");
 
-		String clientRunConfig = RunConfig.clientRunConfig(getProject()).fromDummy("eclipse_run_config_template.xml");
+		for (RunConfigSettings settings : extension.getRuns()) {
-		String serverRunConfig = RunConfig.serverRunConfig(getProject()).fromDummy("eclipse_run_config_template.xml");
+			String name = settings.getName();
 
-		if (!clientRunConfigs.exists() || RunConfig.needsUpgrade(clientRunConfigs)) {
+			File configs = new File(getProject().getRootDir(), eclipseModel.getProject().getName() + "_" + name + ".launch");
-			FileUtils.writeStringToFile(clientRunConfigs, clientRunConfig, StandardCharsets.UTF_8);
+			RunConfig configInst = RunConfig.runConfig(getProject(), settings);
-		}
+			String config = configInst.fromDummy("eclipse_run_config_template.xml");
 
-		if (!serverRunConfigs.exists() || RunConfig.needsUpgrade(serverRunConfigs)) {
+			if (!configs.exists()) {
-			FileUtils.writeStringToFile(serverRunConfigs, serverRunConfig, StandardCharsets.UTF_8);
+				FileUtils.writeStringToFile(configs, config, StandardCharsets.UTF_8);
-		}
+			}
 
-		File runDir = new File(getProject().getRootDir(), getExtension().runDir);
+			settings.makeRunDir();
-
-		if (!runDir.exists()) {
-			runDir.mkdirs();
 		}
 	}
 }

src/main/java/net/fabricmc/loom/task/GenIdeaProjectTask.java

@@ -46,6 +46,7 @@ import org.xml.sax.SAXException;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.RunConfig;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
 
 public class GenIdeaProjectTask extends AbstractLoomTask {
 	@TaskAction
@@ -82,8 +83,10 @@ public class GenIdeaProjectTask extends AbstractLoomTask {
 			throw new RuntimeException("Failed to generate IntelliJ run configurations (runManager was not found)");
 		}
 
-		runManager.appendChild(RunConfig.clientRunConfig(project).genRuns(runManager));
+		for (RunConfigSettings settings : getExtension().getRuns()) {
-		runManager.appendChild(RunConfig.serverRunConfig(project).genRuns(runManager));
+			runManager.appendChild(RunConfig.runConfig(project, settings).genRuns(runManager));
+			settings.makeRunDir();
+		}
 
 		TransformerFactory transformerFactory = TransformerFactory.newInstance();
 		Transformer transformer = transformerFactory.newTransformer();
@@ -92,11 +95,5 @@ public class GenIdeaProjectTask extends AbstractLoomTask {
 		transformer.setOutputProperty(OutputKeys.INDENT, "yes");
 		transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
 		transformer.transform(source, result);
-
-		File runDir = new File(getProject().getRootDir(), extension.runDir);
-
-		if (!runDir.exists()) {
-			runDir.mkdirs();
-		}
 	}
 }

src/main/java/net/fabricmc/loom/task/GenVsCodeProjectTask.java

@@ -38,6 +38,7 @@ import org.gradle.api.tasks.TaskAction;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.RunConfig;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
 
 // Recommended vscode plugins:
 // https://marketplace.visualstudio.com/items?itemName=redhat.java
@@ -61,8 +62,11 @@ public class GenVsCodeProjectTask extends AbstractLoomTask {
 		}
 
 		VsCodeLaunch launch = new VsCodeLaunch();
-		launch.add(RunConfig.clientRunConfig(project));
+
-		launch.add(RunConfig.serverRunConfig(project));
+		for (RunConfigSettings settings : getExtension().getRuns()) {
+			launch.add(RunConfig.runConfig(project, settings));
+			settings.makeRunDir();
+		}
 
 		Gson gson = new GsonBuilder().setPrettyPrinting().create();
 		String json = gson.toJson(launch);
@@ -72,12 +76,6 @@ public class GenVsCodeProjectTask extends AbstractLoomTask {
 		} catch (IOException e) {
 			throw new RuntimeException("Failed to write launch.json", e);
 		}
-
-		File runDir = new File(project.getRootDir(), extension.runDir);
-
-		if (!runDir.exists()) {
-			runDir.mkdirs();
-		}
 	}
 
 	private static class VsCodeLaunch {
@@ -94,7 +92,7 @@ public class GenVsCodeProjectTask extends AbstractLoomTask {
 		public String type = "java";
 		public String name;
 		public String request = "launch";
-		public String cwd = "${workspaceFolder}/run";
+		public String cwd;
 		public String console = "internalConsole";
 		public boolean stopOnEntry = false;
 		public String mainClass;
@@ -106,6 +104,7 @@ public class GenVsCodeProjectTask extends AbstractLoomTask {
 			this.mainClass = runConfig.mainClass;
 			this.vmArgs = runConfig.vmArgs;
 			this.args = runConfig.programArgs;
+			this.cwd = "${workspaceFolder}/" + runConfig.runDir;
 		}
 	}
 }

src/main/java/net/fabricmc/loom/task/LoomTasks.java

@@ -29,6 +29,7 @@ import org.gradle.api.tasks.TaskContainer;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.api.decompilers.LoomDecompiler;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
 import net.fabricmc.loom.decompilers.fernflower.FabricFernFlowerDecompiler;
 
 public final class LoomTasks {
@@ -40,7 +41,7 @@ public final class LoomTasks {
 
 		tasks.register("migrateMappings", MigrateMappingsTask.class, t -> {
 			t.setDescription("Migrates mappings to a new version.");
-			t.getOutputs().upToDateWhen((o) -> false);
+			t.getOutputs().upToDateWhen(o -> false);
 		});
 
 		tasks.register("remapJar", RemapJarTask.class, t -> {
@@ -52,7 +53,7 @@ public final class LoomTasks {
 		tasks.register("remapSourcesJar", RemapSourcesJarTask.class, t -> t.setDescription("Remaps the project sources jar to intermediary names."));
 
 		registerIDETasks(tasks);
-		registerRunTasks(tasks);
+		registerRunTasks(tasks, project);
 		registerDecompileTasks(tasks, project);
 	}
 
@@ -81,25 +82,31 @@ public final class LoomTasks {
 		});
 	}
 
-	private static void registerRunTasks(TaskContainer tasks) {
+	private static void registerRunTasks(TaskContainer tasks, Project project) {
-		tasks.register("runClient", RunClientTask.class, t -> {
+		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
-			t.setDescription("Starts a development version of the Minecraft client.");
-			t.dependsOn("downloadAssets");
-			t.setGroup("fabric");
-		});
 
-		tasks.register("runServer", RunServerTask.class, t -> {
+		extension.getRuns().create("client", RunConfigSettings::client);
-			t.setDescription("Starts a development version of the Minecraft server.");
+		extension.getRuns().create("server", RunConfigSettings::server);
-			t.setGroup("fabric");
+
+		project.afterEvaluate(p -> {
+			for (RunConfigSettings config : extension.getRuns()) {
+				String configName = config.getName();
+				String taskName = "run" + configName.substring(0, 1).toUpperCase() + configName.substring(1);
+
+				tasks.register(taskName, RunGameTask.class, config).configure(t -> {
+					t.setDescription("Starts the '" + config.getConfigName() + "' run configuration");
+					t.setGroup("fabric");
+				});
+			}
 		});
 	}
 
 	private static void registerDecompileTasks(TaskContainer tasks, Project project) {
 		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
 
-		project.afterEvaluate((p) -> {
+		project.afterEvaluate(p -> {
 			for (LoomDecompiler decompiler : extension.getDecompilers()) {
-				String taskName = (decompiler instanceof FabricFernFlowerDecompiler) ? "genSources" : "genSourcesWith" + decompiler.name();
+				String taskName = decompiler instanceof FabricFernFlowerDecompiler ? "genSources" : "genSourcesWith" + decompiler.name();
 				// decompiler will be passed to the constructor of GenerateSourcesTask
 				tasks.register(taskName, GenerateSourcesTask.class, decompiler);
 			}

src/main/java/net/fabricmc/loom/task/RunClientTask.java

@@ -24,10 +24,15 @@
 
 package net.fabricmc.loom.task;
 
+import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.RunConfig;
 
+@Deprecated // Replaced by RunGameTask
 public class RunClientTask extends AbstractRunTask {
 	public RunClientTask() {
-		super(RunConfig::clientRunConfig);
+		super(project -> {
+			LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+			return RunConfig.runConfig(project, extension.getRuns().getByName("client"));
+		});
 	}
 }

src/main/java/net/fabricmc/loom/task/RunGameTask.java

@@ -0,0 +1,37 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.task;
+
+import javax.inject.Inject;
+
+import net.fabricmc.loom.configuration.ide.RunConfig;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
+
+public class RunGameTask extends AbstractRunTask {
+	@Inject
+	public RunGameTask(RunConfigSettings settings) {
+		super(proj -> RunConfig.runConfig(proj, settings));
+	}
+}

src/main/java/net/fabricmc/loom/task/RunServerTask.java

@@ -24,10 +24,15 @@
 
 package net.fabricmc.loom.task;
 
+import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.RunConfig;
 
+@Deprecated // Replaced by RunGameTask
 public class RunServerTask extends AbstractRunTask {
 	public RunServerTask() {
-		super(RunConfig::serverRunConfig);
+		super(project -> {
+			LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+			return RunConfig.runConfig(project, extension.getRuns().getByName("client"));
+		});
 	}
 }

src/main/java/net/fabricmc/loom/util/Constants.java

@@ -126,4 +126,12 @@ public class Constants {
 		private LaunchWrapper() {
 		}
 	}
+
+	public static final class Knot {
+		public static final String KNOT_CLIENT = "net.fabricmc.loader.launch.knot.KnotClient";
+		public static final String KNOT_SERVER = "net.fabricmc.loader.launch.knot.KnotServer";
+
+		private Knot() {
+		}
+	}
 }

src/main/resources/eclipse_run_config_template.xml

@@ -12,5 +12,5 @@
     <stringAttribute key="org.eclipse.jdt.launching.PROGRAM_ARGUMENTS" value="%PROGRAM_ARGS%"/>
     <stringAttribute key="org.eclipse.jdt.launching.PROJECT_ATTR" value="%ECLIPSE_PROJECT%"/>
     <stringAttribute key="org.eclipse.jdt.launching.VM_ARGUMENTS" value="%VM_ARGS%"/>
-    <stringAttribute key="org.eclipse.jdt.launching.WORKING_DIRECTORY" value="${workspace_loc:%ECLIPSE_PROJECT%}/run"/>
+    <stringAttribute key="org.eclipse.jdt.launching.WORKING_DIRECTORY" value="${workspace_loc:%ECLIPSE_PROJECT%}/%RUN_DIRECTORY%"/>
 </launchConfiguration>

src/main/resources/idea_run_config_template.xml

@@ -4,9 +4,9 @@
     <module name="%IDEA_MODULE%" />
     <option name="PROGRAM_PARAMETERS" value="%PROGRAM_ARGS%" />
     <option name="VM_PARAMETERS" value="%VM_ARGS%" />
-    <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/run/" />
+    <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/%RUN_DIRECTORY%/" />
     <method v="2">
       <option name="Make" enabled="true" />
     </method>
   </configuration>
-</component>
+</component>

src/test/groovy/net/fabricmc/loom/MixinBuildFunctionalTest.groovy

@@ -54,7 +54,7 @@ class MixinBuildFunctionalTest extends Specification {
 		when:
 		def result = GradleRunner.create()
 				.withProjectDir(testProjectDir.root)
-				.withArguments('build')
+				.withArguments('build','--stacktrace')
 				.withPluginClasspath()
 				.forwardOutput()
 				.build()