Fix #175: Add a RunModel property to replace the log4j2.xml file

Author: Technici4n

src/main/java/net/neoforged/moddevgradle/dsl/RunModel.java

@@ -14,6 +14,7 @@
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.dsl.Dependencies;
 import org.gradle.api.file.DirectoryProperty;
+import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.MapProperty;
 import org.gradle.api.provider.Property;
@@ -243,6 +244,12 @@ public Configuration getAdditionalRuntimeClasspathConfiguration() {
      */
     public abstract Property<Level> getLogLevel();
 
+    /**
+     * Overrides the {@code log4j2.xml} configuration file.
+     * If unset, MDG will use a default configuration file with the chosen {@link #getLogLevel() log level}.
+     */
+    public abstract RegularFileProperty getLog4jConfigurationFile();
+
     /**
      * Sets the source set to be used as the main classpath of this run.
      * Defaults to the {@code main} source set.

src/main/java/net/neoforged/moddevgradle/internal/ModDevRunWorkflow.java

@@ -332,6 +332,7 @@ private static TaskProvider<PrepareRun> setupRunInGradle(
             task.getGameDirectory().set(run.getGameDirectory());
             task.getVmArgsFile().set(RunUtils.getArgFile(argFileDir, run, RunUtils.RunArgFile.VMARGS));
             task.getProgramArgsFile().set(RunUtils.getArgFile(argFileDir, run, RunUtils.RunArgFile.PROGRAMARGS));
+            task.getLog4jConfigFileOverride().set(run.getLog4jConfigurationFile());
             task.getLog4jConfigFile().set(RunUtils.getArgFile(argFileDir, run, RunUtils.RunArgFile.LOG4J_CONFIG));
             task.getRunType().set(run.getType());
             task.getRunTypeTemplatesSource().from(runTemplatesFile);

src/main/java/net/neoforged/moddevgradle/internal/PrepareRunOrTest.java

@@ -4,6 +4,7 @@
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -55,6 +56,17 @@ abstract class PrepareRunOrTest extends DefaultTask {
     @OutputFile
     public abstract RegularFileProperty getProgramArgsFile();
 
+    /**
+     * A file to use for the {@code log4j2.xml} config file that will be written.
+     * If absent, the standard log4j2.xml file produced by {@link RunUtils#writeLog4j2Configuration} will be used.
+     */
+    @InputFile
+    @Optional
+    public abstract RegularFileProperty getLog4jConfigFileOverride();
+
+    /**
+     * Where the {@code log4j2.xml} config file will be written.
+     */
     @OutputFile
     @Optional
     public abstract RegularFileProperty getLog4jConfigFile();
@@ -239,7 +251,11 @@ private void writeJvmArguments(UserDevRunType runConfig, Map<String, String> add
 
         if (getLog4jConfigFile().isPresent()) {
             var log4jConfigFile = getLog4jConfigFile().get().getAsFile();
-            RunUtils.writeLog4j2Configuration(getGameLogLevel().get(), log4jConfigFile.toPath());
+            if (getLog4jConfigFileOverride().isPresent()) {
+                Files.copy(getLog4jConfigFileOverride().get().getAsFile().toPath(), log4jConfigFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
+            } else {
+                RunUtils.writeLog4j2Configuration(getGameLogLevel().get(), log4jConfigFile.toPath());
+            }
             lines.add(RunUtils.escapeJvmArg("-Dlog4j2.configurationFile=" + log4jConfigFile.getAbsolutePath()));
         }