Add external reader support in pkl-gradle

Author: HT154

pkl-gradle/src/main/java/org/pkl/gradle/ExternalReader.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright © 2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.gradle;
+
+import java.io.Serializable;
+import java.util.List;
+import org.pkl.core.util.Nullable;
+
+public record ExternalReader(String executable, @Nullable List<String> arguments)
+    implements Serializable {
+  public ExternalReader(String executable) {
+    this(executable, null);
+  }
+}

pkl-gradle/src/main/java/org/pkl/gradle/PklPlugin.java

@@ -472,6 +472,8 @@ private <T extends BasePklTask, S extends BasePklSpec> void configureBaseTask(T
     task.getHttpProxy().set(spec.getHttpProxy());
     task.getHttpNoProxy().set(spec.getHttpNoProxy());
     task.getHttpRewrites().set(spec.getHttpRewrites());
+    task.getExternalModuleReaders().set(spec.getExternalModuleReaders());
+    task.getExternalResourceReaders().set(spec.getExternalResourceReaders());
   }
 
   private List<File> getTransitiveModules(AnalyzeImportsTask analyzeTask) {

pkl-gradle/src/main/java/org/pkl/gradle/spec/BasePklSpec.java

@@ -22,6 +22,7 @@
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.MapProperty;
 import org.gradle.api.provider.Property;
+import org.pkl.gradle.ExternalReader;
 
 /** Configuration options shared between plugin features. Documented in user manual. */
 public interface BasePklSpec {
@@ -59,4 +60,8 @@ public interface BasePklSpec {
   ListProperty<String> getHttpNoProxy();
 
   MapProperty<URI, URI> getHttpRewrites();
+  
+  MapProperty<String, ExternalReader> getExternalModuleReaders();
+
+  MapProperty<String, ExternalReader> getExternalResourceReaders();
 }

pkl-gradle/src/main/java/org/pkl/gradle/task/BasePklTask.java

@@ -40,12 +40,15 @@
 import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.InputFiles;
 import org.gradle.api.tasks.Internal;
+import org.gradle.api.tasks.Nested;
 import org.gradle.api.tasks.Optional;
 import org.gradle.api.tasks.TaskAction;
 import org.pkl.commons.cli.CliBaseOptions;
 import org.pkl.core.evaluatorSettings.Color;
+import org.pkl.core.evaluatorSettings.PklEvaluatorSettings;
 import org.pkl.core.util.LateInit;
 import org.pkl.core.util.Nullable;
+import org.pkl.gradle.ExternalReader;
 import org.pkl.gradle.utils.PluginUtils;
 
 public abstract class BasePklTask extends DefaultTask {
@@ -145,6 +148,14 @@ public Provider<String> getEvalRootDirPath() {
   @Input
   @Optional
   public abstract MapProperty<URI, URI> getHttpRewrites();
+  
+  @Input
+  @Optional
+  public abstract MapProperty<String, ExternalReader> getExternalModuleReaders();
+
+  @Input
+  @Optional
+  public abstract MapProperty<String, ExternalReader> getExternalResourceReaders();
 
   /**
    * There are issues with using native libraries in Gradle plugins. As a workaround for now, make
@@ -200,8 +211,8 @@ protected CliBaseOptions getCliBaseOptions() {
               getHttpProxy().getOrNull(),
               getHttpNoProxy().getOrElse(List.of()),
               getHttpRewrites().getOrNull(),
-              Map.of(),
-              Map.of(),
+              parseExternalReaders(getExternalModuleReaders()),
+              parseExternalReaders(getExternalResourceReaders()),
               null);
     }
     return cachedOptions;
@@ -237,4 +248,15 @@ protected List<Pattern> patternsFromStrings(List<String> patterns) {
     @Nullable T value = provider.getOrNull();
     return value == null ? null : f.apply(value);
   }
+
+  protected Map<String, PklEvaluatorSettings.ExternalReader> parseExternalReaders(
+      Provider<Map<String, ExternalReader>> provider) {
+    return provider.getOrElse(Map.of()).entrySet().stream()
+        .collect(
+            Collectors.toMap(
+                Map.Entry::getKey,
+                (it) ->
+                    new PklEvaluatorSettings.ExternalReader(
+                        it.getValue().executable(), it.getValue().arguments())));
+  }
 }

pkl-gradle/src/main/java/org/pkl/gradle/task/ModulesTask.java

@@ -164,8 +164,8 @@ protected CliBaseOptions getCliBaseOptions() {
               null,
               List.of(),
               getHttpRewrites().getOrNull(),
-              Map.of(),
-              Map.of(),
+              parseExternalReaders(getExternalModuleReaders()),
+              parseExternalReaders(getExternalResourceReaders()),
               null);
     }
     return cachedOptions;