HDDS-499. Display descriptions for properties on the configuration page

hadoop-hdds/framework/src/main/java/org/apache/hadoop/hdds/conf/HddsConfServlet.java

@@ -19,7 +19,9 @@
 
 import com.google.common.annotations.VisibleForTesting;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.Writer;
+import java.net.URL;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
@@ -28,10 +30,20 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.ws.rs.core.HttpHeaders;
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import org.apache.commons.lang3.StringUtils;
 import org.apache.hadoop.hdds.annotation.InterfaceAudience;
 import org.apache.hadoop.hdds.annotation.InterfaceStability;
 import org.apache.hadoop.hdds.server.JsonUtils;
 import org.apache.hadoop.hdds.server.http.HttpServer2;
+import org.apache.hadoop.util.XMLUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
 
 /**
  * A servlet to print out the running configuration data.
@@ -41,13 +53,53 @@
 public class HddsConfServlet extends HttpServlet {
 
   private static final long serialVersionUID = 1L;
+  private static final Logger LOG = LoggerFactory.getLogger(HddsConfServlet.class);
 
   protected static final String FORMAT_JSON = "json";
   protected static final String FORMAT_XML = "xml";
   private static final String COMMAND = "cmd";
   private static final OzoneConfiguration OZONE_CONFIG =
       new OzoneConfiguration();
 
+  /**
+   * Represents metadata for a configuration property, including its name, value and description.
+   */
+  public static class PropertyMetadata {
+    private String name;
+    private String value;
+    private String description;
+
+    public PropertyMetadata(String name, String value, String description) {
+      this.name = name;
+      this.value = value;
+      this.description = description;
+    }
+
+    public String getName() {
+      return name;
+    }
+
+    public void setName(String name) {
+      this.name = name;
+    }
+
+    public String getValue() {
+      return value;
+    }
+
+    public void setValue(String value) {
+      this.value = value;
+    }
+
+    public String getDescription() {
+      return description;
+    }
+
+    public void setDescription(String description) {
+      this.description = description;
+    }
+  }
+
   /**
    * Return the Configuration of the daemon hosting this servlet.
    * This is populated when the HttpServer starts.
@@ -149,12 +201,21 @@ private void processConfigTagRequest(HttpServletRequest request, String cmd,
         throw new IllegalArgumentException("The tags parameter should be set" +
                 " when using the getPropertyByTag command.");
       }
-      Map<String, Properties> propMap = new HashMap<>();
+
+      Map<String, String> descriptionMap = buildDescriptionMap(config);
+      Map<String, Map<String, PropertyMetadata>> propMap = new HashMap<>();
 
       for (String tag : tags.split(",")) {
         if (config.isPropertyTag(tag)) {
           Properties properties = config.getAllPropertiesByTag(tag);
-          propMap.put(tag, properties);
+          Map<String, PropertyMetadata> metadataMap = new HashMap<>();
+
+          for (String propName : properties.stringPropertyNames()) {
+            String value = properties.getProperty(propName);
+            String description = descriptionMap.getOrDefault(propName, "");
+            metadataMap.put(propName, new PropertyMetadata(propName, value, description));
+          }
+          propMap.put(tag, metadataMap);
         }
       }
       out.write(JsonUtils.toJsonString(propMap));
@@ -165,6 +226,92 @@ private void processConfigTagRequest(HttpServletRequest request, String cmd,
 
   }
 
+  /**
+   * Build a map of property names to descriptions by reading from configuration resources.
+   * @param config the OzoneConfiguration to extract descriptions from
+   * @return map of property name to description
+   */
+  private Map<String, String> buildDescriptionMap(OzoneConfiguration config) {
+    Map<String, String> descriptionMap = new HashMap<>();
+
+    // List of configuration resource names to check
+    String[] configResources = new String[] {
+        "core-default.xml",
+        "core-site.xml",
+        "hdfs-default.xml",
+        "hdfs-site.xml",
+        "hdds-common-default.xml",
+        "hdds-client-default.xml",
+        "hdds-container-service-default.xml",
+        "hdds-server-framework-default.xml",
+        "hdds-server-scm-default.xml",
+        "ozone-common-default.xml",
+        "ozone-csi-default.xml",
+        "ozone-manager-default.xml",
+        "ozone-recon-default.xml",
+        "ozone-default.xml",
+        "ozone-site.xml"
+    };
+
+    for (String resourceName : configResources) {
+      try {
+        URL resourceUrl = config.getResource(resourceName);
+        if (resourceUrl != null) {
+          parseXmlDescriptions(resourceUrl, descriptionMap);
+        }
+      } catch (Exception e) {
+        LOG.error("Could not read descriptions from resource: {}", resourceName, e);
+      }
+    }
+
+    return descriptionMap;
+  }
+
+  /**
+   * Parse XML configuration file and extract property descriptions using DOM parser.
+   * @param resourceUrl URL of the XML resource to parse
+   * @param descriptionMap map to populate with property name -> description mappings
+   */
+  private void parseXmlDescriptions(URL resourceUrl, Map<String, String> descriptionMap) {
+    try (InputStream inputStream = resourceUrl.openStream()) {
+      DocumentBuilderFactory factory = XMLUtils.newSecureDocumentBuilderFactory();
+      DocumentBuilder builder = factory.newDocumentBuilder();
+      Document doc = builder.parse(inputStream);
+
+      NodeList propertyNodes = doc.getElementsByTagName("property");
+      for (int i = 0; i < propertyNodes.getLength(); i++) {
+        Node propertyNode = propertyNodes.item(i);
+        if (propertyNode.getNodeType() == Node.ELEMENT_NODE) {
+          Element propertyElement = (Element) propertyNode;
+
+          String name = getTextContent(propertyElement, "name");
+          String description = getTextContent(propertyElement, "description");
+
+          if (name != null && !StringUtils.isBlank(description)) {
+            descriptionMap.put(name, description.trim());
+          }
+        }
+      }
+    } catch (Exception e) {
+      LOG.error("Failed to parse XML from resource: {}", resourceUrl, e);
+    }
+  }
+
+  /**
+   * Get text content of a child element by tag name.
+   * @param parent parent element
+   * @param tagName tag name of child element
+   * @return text content of the child element, or null if not found
+   */
+  private String getTextContent(Element parent, String tagName) {
+    NodeList nodeList = parent.getElementsByTagName(tagName);
+    if (nodeList.getLength() > 0) {
+      Node node = nodeList.item(0);
+      return node.getTextContent();
+    }
+    return null;
+  }
+
   private static OzoneConfiguration getOzoneConfig() {
     return OZONE_CONFIG;
   }

hadoop-hdds/framework/src/main/resources/webapps/static/ozone.js

@@ -296,13 +296,15 @@
         for (var idx in srcObj) {
           //console.log("Adding keys for "+idx)
           for (var key in srcObj[idx]) {
-
+            var propMetadata = srcObj[idx][key];
+
             if (ctrl.keyTagMap.hasOwnProperty(key)) {
               ctrl.keyTagMap[key]['tag'].push(idx);
             } else {
               var newProp = {};
-              newProp['name'] = key;
-              newProp['value'] = srcObj[idx][key];
+              newProp['name'] = propMetadata.name || key;
+              newProp['value'] = propMetadata.value;
+              newProp['description'] = propMetadata.description || '';
               newProp['tag'] = [];
               newProp['tag'].push(idx);
               ctrl.keyTagMap[key] = newProp;
@@ -392,4 +394,4 @@
     }
   });
 
-})();
+})();

hadoop-hdds/framework/src/main/resources/webapps/static/templates/config.html

@@ -81,8 +81,8 @@
       <tbody>
       <tr
           ng-repeat="config in $ctrl.configs | filter:search | orderBy:$ctrl.propertyName:$ctrl.reverse">
-        <td style="word-wrap: break-word;">{{config.name}}</td>
-        <td style="word-wrap: break-word;">{{config.value}}</td>
+        <td style="word-wrap: break-word; font-family: monospace;">{{config.name}}</td>
+        <td style="word-wrap: break-word; font-family: monospace;">{{config.value}}</td>
         <td style="word-wrap: break-word;">{{config.description}}</td>
       </tr>
       </tbody>