[fix][broker] Extract additional servlets to the default directory by… (

#17477)

pulsar-broker-common/src/main/java/org/apache/pulsar/broker/web/plugin/servlet/AdditionalServlets.java

@@ -23,6 +23,7 @@
 import java.util.Map;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.StringUtils;
 import org.apache.pulsar.common.configuration.PulsarConfiguration;
 import org.apache.pulsar.common.nar.NarClassLoader;
 
@@ -70,7 +71,7 @@ public static AdditionalServlets load(PulsarConfiguration conf) throws IOExcepti
         }
 
         String narExtractionDirectory = conf.getProperties().getProperty(NAR_EXTRACTION_DIRECTORY);
-        if (narExtractionDirectory == null) {
+        if (StringUtils.isBlank(narExtractionDirectory)) {
             narExtractionDirectory = NarClassLoader.DEFAULT_NAR_EXTRACTION_DIR;
         }
 

pulsar-broker-common/src/test/java/org/apache/pulsar/broker/web/plugin/servlet/AdditionalServletsTest.java

@@ -0,0 +1,82 @@
+/**
+ * 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.pulsar.broker.web.plugin.servlet;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.mockStatic;
+import org.apache.pulsar.common.configuration.PulsarConfiguration;
+import org.mockito.MockedStatic;
+import org.mockito.Mockito;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+import java.io.IOException;
+import java.nio.file.Paths;
+import java.util.Properties;
+
+public class AdditionalServletsTest {
+
+
+    @Test
+    public void testEmptyStringAsExtractionDirectory() throws IOException {
+        Properties p = new Properties();
+        p.put("narExtractionDirectory", "");
+        p.put("additionalServlets", "AS1,AS2");
+        p.put("additionalServletDirectory", "/additionalServletDirectory");
+
+        PulsarConfiguration config = mock(PulsarConfiguration.class);
+        Mockito.when(config.getProperties()).thenReturn(p);
+
+        AdditionalServletMetadata asm1 = additionalServletMetadata(1);
+        AdditionalServletMetadata asm2 = additionalServletMetadata(2);
+
+        AdditionalServletDefinitions definitions = new AdditionalServletDefinitions();
+        definitions.servlets().put("AS1", asm1);
+        definitions.servlets().put("AS2", asm2);
+
+        AdditionalServletWithClassLoader as1 = mock(AdditionalServletWithClassLoader.class);
+        AdditionalServletWithClassLoader as2 = mock(AdditionalServletWithClassLoader.class);
+
+        String originalTmpDirectory = System.getProperty("java.io.tmpdir");
+        try (MockedStatic<AdditionalServletUtils> utils = mockStatic(AdditionalServletUtils.class)) {
+            String tmpDirectory = "/my/tmp/directory";
+            System.setProperty("java.io.tmpdir", tmpDirectory);
+            utils.when(() -> AdditionalServletUtils.searchForServlets(
+                    "/additionalServletDirectory", tmpDirectory)).thenReturn(definitions);
+            utils.when(() -> AdditionalServletUtils.load(asm1, tmpDirectory)).thenReturn(as1);
+            utils.when(() -> AdditionalServletUtils.load(asm2, tmpDirectory)).thenReturn(as2);
+
+            AdditionalServlets servlets = AdditionalServlets.load(config);
+
+            Assert.assertEquals(servlets.getServlets().get("AS1"), as1);
+            Assert.assertEquals(servlets.getServlets().get("AS2"), as2);
+        } finally {
+            System.setProperty("java.io.tmpdir", originalTmpDirectory);
+        }
+    }
+
+    private AdditionalServletMetadata additionalServletMetadata(int index) {
+        AdditionalServletMetadata as = new AdditionalServletMetadata();
+        as.setArchivePath(Paths.get("/additionalServletDirectory/" + index));
+        as.setDefinition(new AdditionalServletDefinition());
+        as.getDefinition().setName("as" + index);
+        as.getDefinition().setAdditionalServletClass("com.example.AS" + index);
+        as.getDefinition().setDescription("Additional Servlet " +index);
+        return as;
+    }
+}