KNOX-3051: Ability to extend classpath with configurable paths (#971)

* KNOX-3051: Ability to extend classpath with configurable paths

* KNOX-3051: Code cleanup

* KNOX-3051: Rename Extender class, modified Extender to not retain reference to the properties

gateway-util-launcher/src/main/java/org/apache/knox/gateway/launcher/Command.java

@@ -19,6 +19,7 @@
 
 import java.io.File;
 import java.io.FilenameFilter;
+import java.io.IOException;
 import java.lang.reflect.InvocationTargetException;
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -53,14 +54,17 @@ class Command {
   Boolean fork = Boolean.FALSE;
   Boolean redirect = Boolean.FALSE; // Controls redirecting stderr to stdout if forking.
   Boolean restream = Boolean.TRUE; // Controls creation of threads to read/write stdin, stdout, stderr of child if forking.
+  GatewayServerClasspathExtender gatewayServerClasspathExtender;
 
-  Command( File base, Properties config, String[] args ) throws MalformedURLException {
+  Command( File base, Properties config, String[] args ) throws IOException {
     this.base = base;
     this.mainArgs = args ;
+    this.gatewayServerClasspathExtender = new GatewayServerClasspathExtender( base );
     consumeConfig( config );
   }
 
-  void consumeConfig( Properties config ) throws MalformedURLException {
+  void consumeConfig( Properties config ) throws IOException {
+    gatewayServerClasspathExtender.extendClassPathProperty(config);
     mainClass = config.getProperty( MAIN_CLASS );
     config.remove( MAIN_CLASS );
     mainMethod = config.getProperty( MAIN_METHOD, mainMethod );

gateway-util-launcher/src/main/java/org/apache/knox/gateway/launcher/GatewayServerClasspathExtender.java

@@ -0,0 +1,75 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.knox.gateway.launcher;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.Properties;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class GatewayServerClasspathExtender {
+
+    private static final String CLASSPATH_EXTENSION_PROPERTY = "gateway.server.classpath.extension";
+    private static final String CLASSPATH_PROPERTY_PATTERN = "<property>\\s*<name>" + CLASSPATH_EXTENSION_PROPERTY + "</name>\\s*<value>(.*?)</value>\\s*</property>";
+    private static final String CONFIG_FILE = "gateway-site.xml";
+    private static final String CONFIG_PATH = "../conf/" + CONFIG_FILE;
+    private static final String CLASS_PATH_PROPERTY = "class.path";
+    private static final String MAIN_CLASS_PROPERTY = "main.class";
+    private static final String GATEWAY_SERVER_MAIN_CLASS = "org.apache.knox.gateway.GatewayServer";
+    private static final String[] CLASS_PATH_DELIMITERS = new String[]{",", ";"};
+
+    private final File base;
+    private final Pattern pattern = Pattern.compile(CLASSPATH_PROPERTY_PATTERN, Pattern.DOTALL);
+
+    public GatewayServerClasspathExtender(File base) {
+        this.base = base;
+    }
+
+    public void extendClassPathProperty(Properties properties) throws IOException {
+        Path configFilePath = Paths.get(base.getPath(), CONFIG_PATH);
+        if (GATEWAY_SERVER_MAIN_CLASS.equals(properties.getProperty(MAIN_CLASS_PROPERTY)) && Files.isReadable(configFilePath)) {
+            String configContent = new String(Files.readAllBytes(configFilePath), StandardCharsets.UTF_8);
+            extractExtensionPathIntoProperty(configContent, properties);
+        }
+    }
+
+    protected void extractExtensionPathIntoProperty(String configContent, Properties properties) {
+        final Matcher matcher = pattern.matcher(configContent);
+
+        if (matcher.find()) {
+            StringBuilder newClassPath = new StringBuilder(matcher.group(1).trim());
+            if (newClassPath.length() > 0) {
+                if (!endsWithDelimiter(newClassPath.toString())) {
+                    newClassPath.append(CLASS_PATH_DELIMITERS[1]);
+                }
+                newClassPath.append(properties.getProperty(CLASS_PATH_PROPERTY));
+                properties.setProperty(CLASS_PATH_PROPERTY, newClassPath.toString());
+            }
+        }
+    }
+
+    private boolean endsWithDelimiter(String path) {
+        return Arrays.stream(CLASS_PATH_DELIMITERS).anyMatch(path::endsWith);
+    }
+}

gateway-util-launcher/src/test/java/org/apache/knox/gateway/launcher/GatewayServerClasspathExtenderTest.java

@@ -0,0 +1,176 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.knox.gateway.launcher;
+
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Properties;
+
+import static org.junit.Assert.assertEquals;
+
+public class GatewayServerClasspathExtenderTest {
+
+    private Path tempDir;
+    private Path confDir;
+    private Path configFilePath;
+
+    @Before
+    public void setupDirs() throws IOException {
+        tempDir = Files.createTempDirectory("cp_extender_test");
+        confDir = Files.createDirectory(tempDir.resolve("conf"));
+        configFilePath = confDir.resolve("gateway-site.xml");
+    }
+
+    @After
+    public void cleanUpDirs() throws IOException {
+        Files.deleteIfExists(configFilePath);
+        Files.deleteIfExists(confDir);
+        Files.deleteIfExists(tempDir);
+    }
+
+    @Test
+    public void extendClassPathPropertyTest() throws IOException {
+        Properties properties = new Properties();
+        properties.setProperty("class.path", "classpath");
+        properties.setProperty("main.class", "org.apache.knox.gateway.GatewayServer");
+        GatewayServerClasspathExtender gatewayServerClasspathExtender = new GatewayServerClasspathExtender(confDir.toFile());
+
+        String configContent = this.getConfigContent("/new/classp/*");
+        Files.write(configFilePath, configContent.getBytes(StandardCharsets.UTF_8));
+        gatewayServerClasspathExtender.extendClassPathProperty(properties);
+
+        assertEquals("/new/classp/*;classpath", properties.getProperty("class.path"));
+    }
+
+    @Test
+    public void extendClassPathPropertyDifferentMainClassTest() throws IOException {
+        Properties properties = new Properties();
+        properties.setProperty("class.path", "classpath");
+        properties.setProperty("main.class", "org.apache.knox.gateway.KnoxCLI");
+        GatewayServerClasspathExtender gatewayServerClasspathExtender = new GatewayServerClasspathExtender(confDir.toFile());
+
+        String configContent = this.getConfigContent("/new/classp/*");
+        Files.write(configFilePath, configContent.getBytes(StandardCharsets.UTF_8));
+        gatewayServerClasspathExtender.extendClassPathProperty(properties);
+
+        assertEquals("classpath", properties.getProperty("class.path"));
+    }
+
+    @Test
+    public void extractExtensionPathIntoPropertyNoDelimTest() {
+        Properties properties = new Properties();
+        properties.setProperty("class.path", "classpath");
+        GatewayServerClasspathExtender gatewayServerClasspathExtender = new GatewayServerClasspathExtender(null);
+
+        String configContent = this.getConfigContent("/new/classp/*");
+        gatewayServerClasspathExtender.extractExtensionPathIntoProperty(configContent, properties);
+
+        assertEquals("/new/classp/*;classpath", properties.getProperty("class.path"));
+    }
+
+    @Test
+    public void extractExtensionPathIntoPropertyXMLFormatTest() {
+        Properties properties = new Properties();
+        properties.setProperty("class.path", "classpath");
+        GatewayServerClasspathExtender gatewayServerClasspathExtender = new GatewayServerClasspathExtender(null);
+
+        String configContent = this.getConfigContent("/new/classp/*;");
+        gatewayServerClasspathExtender.extractExtensionPathIntoProperty(configContent, properties);
+
+        assertEquals("/new/classp/*;classpath", properties.getProperty("class.path"));
+    }
+
+    @Test
+    public void extractExtensionPathIntoPropertyWhitespaceTest() {
+        Properties properties = new Properties();
+        properties.setProperty("class.path", "classpath");
+        GatewayServerClasspathExtender gatewayServerClasspathExtender = new GatewayServerClasspathExtender(null);
+
+        String configContent = this.getConfigContent(" /new/classp/*; ");
+        gatewayServerClasspathExtender.extractExtensionPathIntoProperty(configContent, properties);
+
+        assertEquals("/new/classp/*;classpath", properties.getProperty("class.path"));
+    }
+
+    @Test
+    public void extractExtensionPathIntoPropertyMultipleTest() {
+        Properties properties = new Properties();
+        properties.setProperty("class.path", "classpath");
+        GatewayServerClasspathExtender gatewayServerClasspathExtender = new GatewayServerClasspathExtender(null);
+
+        String configContent = this.getConfigContent("/new/classp/*,../classp");
+        gatewayServerClasspathExtender.extractExtensionPathIntoProperty(configContent, properties);
+
+        assertEquals("/new/classp/*,../classp;classpath", properties.getProperty("class.path"));
+    }
+
+    @Test
+    public void extractExtensionPathIntoPropertyEmptyTest() {
+        Properties properties = new Properties();
+        properties.setProperty("class.path", "classpath");
+        GatewayServerClasspathExtender gatewayServerClasspathExtender = new GatewayServerClasspathExtender(null);
+
+        String configContent = this.getConfigContent("");
+        gatewayServerClasspathExtender.extractExtensionPathIntoProperty(configContent, properties);
+
+        assertEquals("classpath", properties.getProperty("class.path"));
+    }
+
+    @Test
+    public void extractExtensionPathIntoPropertyEmptyWhitespaceTest() {
+        Properties properties = new Properties();
+        properties.setProperty("class.path", "classpath");
+        GatewayServerClasspathExtender gatewayServerClasspathExtender = new GatewayServerClasspathExtender(null);
+
+        String configContent = this.getConfigContent(" ");
+        gatewayServerClasspathExtender.extractExtensionPathIntoProperty(configContent, properties);
+
+        assertEquals("classpath", properties.getProperty("class.path"));
+    }
+
+    @Test
+    public void extractExtensionPathIntoPropertyNoConfigTest() throws IOException {
+        Properties properties = new Properties();
+        properties.setProperty("class.path", "classpath");
+        GatewayServerClasspathExtender gatewayServerClasspathExtender = new GatewayServerClasspathExtender(null);
+
+        ClassLoader classLoader = getClass().getClassLoader();
+        File file = new File(classLoader.getResource("gateway-site-test.xml").getFile());
+
+        gatewayServerClasspathExtender.extractExtensionPathIntoProperty(new String(Files.readAllBytes(file.toPath()), StandardCharsets.UTF_8), properties);
+
+        assertEquals("classpath", properties.getProperty("class.path"));
+    }
+
+    private String getConfigContent(String extensionValue) {
+        return "<configuration>\n" +
+                "    <property>\n" +
+                "        <name>gateway.server.classpath.extension</name>\n" +
+                "        <value>" + extensionValue + "</value>\n" +
+                "    </property>\n" +
+                "</configuration>";
+    }
+}