HadoopYARN-11726: Add logging statements for successful and unsucessful password retrieval operations

Author: Hean Chhinling

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/webapp/util/WebAppUtils.java

@@ -47,6 +47,8 @@
 import org.apache.hadoop.yarn.webapp.NotFoundException;
 import org.apache.http.NameValuePair;
 import org.apache.http.client.utils.URLEncodedUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import javax.servlet.http.HttpServletRequest;
 
@@ -61,6 +63,7 @@ public class WebAppUtils {
       "ssl.server.keystore.keypassword";
   public static final String HTTPS_PREFIX = "https://";
   public static final String HTTP_PREFIX = "http://";
+  public static final Logger LOG = LoggerFactory.getLogger(WebAppUtils.class);
 
   public static void setRMWebAppPort(Configuration conf, int port) {
     String hostname = getRMWebAppURLWithoutScheme(conf);
@@ -509,10 +512,12 @@ static String getPassword(Configuration conf, String alias) {
       char[] passchars = conf.getPassword(alias);
       if (passchars != null) {
         password = new String(passchars);
+        LOG.debug("Successful password retrieval for alias: {}", alias);
       }
     }
     catch (IOException ioe) {
       password = null;
+      LOG.error("Unable to retrieve password for alias: {}", alias, ioe);
     }
     return password;
   }