Helidon service Shade maven plugin transformer

etc/checkstyle.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-    Copyright (c) 2016, 2022 Oracle and/or its affiliates.
+    Copyright (c) 2016, 2024 Oracle and/or its affiliates.
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -119,7 +119,10 @@
         <module name="JavadocVariable">
             <property name="scope" value="protected"/>
         </module>
-        <module name="JavadocStyle"/>
+        <module name="JavadocStyle">
+            <!-- https://github.com/checkstyle/checkstyle/issues/3351 -->
+            <property name="checkHtml" value="false"/>
+        </module>
 
         <!-- Checks for Naming Conventions.                  -->
         <!-- See http://checkstyle.sf.net/config_naming.html -->

etc/copyright-exclude.txt

@@ -42,3 +42,4 @@ expected
 expected-config
 .helidon
 jvm.config
+.loader

maven-plugins/pom.xml

@@ -42,5 +42,6 @@
         <module>sitegen-maven-plugin</module>
         <module>snakeyaml-codegen-maven-plugin</module>
         <module>stager-maven-plugin</module>
+        <module>shade-extensions</module>
     </modules>
 </project>

maven-plugins/shade-extensions/README.md

@@ -0,0 +1,42 @@
+# Helidon Shade Maven Plugin Extensions
+
+Allows shading Helidon artefacts with[ Maven Shade plugin](https://maven.apache.org/plugins/maven-shade-plugin/) 
+by providing transformer for aggregating service registry files.
+
+Aggregated files:
+ * `META-INF/helidon/service-registry.json`
+ * `META-INF/helidon/config-metadata.json`
+ * `META-INF/helidon/service.loader`
+ * `META-INF/helidon/serial-config.properties`
+ * `META-INF/helidon/feature-metadata.properties`
+
+### General usage
+
+```xml
+<plugin>
+    <groupId>org.apache.maven.plugins</groupId>
+    <artifactId>maven-shade-plugin</artifactId>
+    <version>3.5.1</version>
+    <executions>
+        <execution>
+            <phase>package</phase>
+            <goals>
+                <goal>shade</goal>
+            </goals>
+            <configuration>
+                <transformers>
+                    <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
+                    <transformer implementation="io.helidon.build.maven.shade.HelidonServiceTransformer"/>
+                </transformers>
+            </configuration>
+        </execution>
+    </executions>
+    <dependencies>
+        <dependency>
+            <groupId>io.helidon.build-tools</groupId>
+            <artifactId>helidon-shade-extensions</artifactId>
+            <version>4.0.0-SNAPSHOT</version>
+        </dependency>
+    </dependencies>
+</plugin>
+```

maven-plugins/shade-extensions/pom.xml

@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    Copyright (c) 2024 Oracle and/or its affiliates.
+
+    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
+
+        http://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.
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>io.helidon.build-tools</groupId>
+        <artifactId>helidon-build-tools-project</artifactId>
+        <version>4.0.0-SNAPSHOT</version>
+        <relativePath>../../pom.xml</relativePath>
+    </parent>
+    <artifactId>helidon-shade-extensions</artifactId>
+    <name>Helidon Shade Maven Plugin Extensions</name>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-shade-plugin</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.glassfish</groupId>
+            <artifactId>javax.json</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

maven-plugins/shade-extensions/src/main/java/io/helidon/build/maven/shade/Aggregator.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * 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
+ *
+ *     http://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 io.helidon.build.maven.shade;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.jar.JarOutputStream;
+
+interface Aggregator {
+    String path();
+    boolean hasTransformedResource();
+    void aggregate(InputStream is) throws IOException;
+    void writeToJar(JarOutputStream jos) throws IOException;
+}

maven-plugins/shade-extensions/src/main/java/io/helidon/build/maven/shade/FeatureMetadataAggregator.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * 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
+ *
+ *     http://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 io.helidon.build.maven.shade;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Optional;
+import java.util.Properties;
+import java.util.jar.JarEntry;
+import java.util.jar.JarOutputStream;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+/**
+ * Feature properties can't be effectively aggregated, instead single feature file is created.
+ *
+ * Example:
+ * <pre>{@code
+ * # Features aggregated by HelidonServiceTransformer during shading:
+ * # - CDI
+ * # - Config
+ * # - Object Mapping
+ * # - YAML
+ * # - Observe
+ * # - CORS
+ * # - WebServer
+ * # - Media
+ * # - Encoding
+ * # - Static Content
+ * # - JSONP
+ * # - Config
+ * # - Encryption
+ * # - WebClient
+ * # - HTTP/1.1
+ * n=Helidon Shaded
+ * d=Helidon modules shaded in to the single module.
+ * }</pre>
+ */
+class FeatureMetadataAggregator implements Aggregator {
+
+    static final String FEATURE_METADATA_PATH = "META-INF/helidon/feature-metadata.properties";
+    private final List<String> features = new LinkedList<>();
+
+    @Override
+    public String path() {
+        return FEATURE_METADATA_PATH;
+    }
+
+    @Override
+    public boolean hasTransformedResource() {
+        return true;
+    }
+
+    @Override
+    public void aggregate(InputStream is) throws IOException {
+        Properties properties = new Properties();
+        properties.load(is);
+        Optional.ofNullable(properties.getProperty("n")).ifPresent(features::add);
+    }
+
+    @Override
+    public void writeToJar(JarOutputStream jos) throws IOException {
+        JarEntry entry = new JarEntry(path());
+        entry.setTime(Long.MIN_VALUE);
+        jos.putNextEntry(entry);
+        Writer writer = new OutputStreamWriter(jos, UTF_8);
+        writer.write("# Features aggregated by HelidonServiceTransformer during shading:");
+        writer.write("\n# - " + String.join("\n# - ", features));
+        writer.write("\nn=Helidon Shaded");
+        writer.write("\nd=Helidon modules shaded in to the single module.");
+        writer.write("\n");
+        writer.flush();
+    }
+}

maven-plugins/shade-extensions/src/main/java/io/helidon/build/maven/shade/HelidonServiceTransformer.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * 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
+ *
+ *     http://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 io.helidon.build.maven.shade;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.jar.JarOutputStream;
+import java.util.stream.Stream;
+
+import org.apache.maven.plugins.shade.relocation.Relocator;
+import org.apache.maven.plugins.shade.resource.ReproducibleResourceTransformer;
+
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Maven Shade plugin custom transformer for merging Helidon service-registry files.
+ * Usage:
+ * <pre>{@code
+ * <plugin>
+ *    <groupId>org.apache.maven.plugins</groupId>
+ *    <artifactId>maven-shade-plugin</artifactId>
+ *    <version>3.5.1</version>
+ *    <executions>
+ *        <execution>
+ *            <phase>package</phase>
+ *            <goals>
+ *                <goal>shade</goal>
+ *            </goals>
+ *            <configuration>
+ *                <transformers>
+ *                    <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
+ *                    <transformer implementation="io.helidon.build.maven.shade.HelidonServiceTransformer"/>
+ *                </transformers>
+ *            </configuration>
+ *        </execution>
+ *    </executions>
+ *    <dependencies>
+ *        <dependency>
+ *            <groupId>io.helidon.build-tools</groupId>
+ *            <artifactId>helidon-shade-extensions</artifactId>
+ *            <version>4.0.0-SNAPSHOT</version>
+ *        </dependency>
+ *    </dependencies>
+ * </plugin>
+ * }</pre>
+ */
+public class HelidonServiceTransformer implements ReproducibleResourceTransformer {
+
+    static final String SERVICE_REGISTRY_PATH = "META-INF/helidon/service-registry.json";
+    static final String CONFIG_METADATA_PATH = "META-INF/helidon/config-metadata.json";
+
+    private final Map<String, Aggregator> aggregators = Stream
+            .of(
+                    new JsonArrayAggregator(SERVICE_REGISTRY_PATH),
+                    new JsonArrayAggregator(CONFIG_METADATA_PATH),
+                    new ServiceLoaderAggregator(),
+                    new SerialConfigAggregator(),
+                    new FeatureMetadataAggregator()
+            )
+            .collect(toMap(Aggregator::path, Function.identity()));
+
+    @Override
+    public boolean canTransformResource(String resource) {
+        return aggregators.containsKey(resource);
+    }
+
+    @Override
+    public void processResource(String resource, InputStream is, List<Relocator> relocators) throws IOException {
+        processResource(resource, is, relocators, 0);
+    }
+
+    @Override
+    public boolean hasTransformedResource() {
+        return aggregators.values().stream().anyMatch(Aggregator::hasTransformedResource);
+    }
+
+    @Override
+    public void modifyOutputStream(JarOutputStream jarOutputStream) throws IOException {
+        for (Aggregator a : aggregators.values()) {
+            a.writeToJar(jarOutputStream);
+        }
+    }
+
+    @Override
+    public void processResource(String resource, InputStream is, List<Relocator> relocators, long time) throws IOException {
+        aggregators.get(resource).aggregate(is);
+    }
+}