PingRequestHandler is now directly configured with a "healthcheckFile" instead of looking for the legacy <admin><healthcheck/></admin> syntax. Filenames specified as relative paths have been fixed so that they are resolved against the data dir instead of the CWD of the java process.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1333598 13f79535-47bb-0310-9956-ffa450edef68

solr/CHANGES.txt

@@ -78,6 +78,12 @@ Upgrading from Solr 3.6-dev
   CommonsHttpSolrServer is now HttpSolrServer, and 
   StreamingUpdateSolrServer is now ConcurrentUpdateSolrServer.
 
+* The PingRequestHandler no longer looks for a <healthcheck/> option in the 
+  (legacy) <admin> section of solrconfig.xml.  Users who wish to take 
+  advantage of this feature should configure a "healthcheckFile" init param 
+  directly on the  PingRequestHandler.  As part of this change, relative file 
+  paths have been fixed to be resolved against the data dir.  See the example 
+  solrconfig.xml and SOLR-1258 for more details.
 
 Detailed Change List
 ----------------------
@@ -535,6 +541,12 @@ Other Changes
 * SOLR-3403: Deprecated Analysis Factories now log their own deprecation messages.
   No logging support is provided by Factory parent classes. (Chris Male)
 
+* SOLR-1258: PingRequestHandler is now directly configured with a 
+  "healthcheckFile" instead of looking for the legacy 
+  <admin><healthcheck/></admin> syntax.  Filenames specified as relative 
+  paths have been fixed so that they are resolved against the data dir 
+  instead of the CWD of the java process. (hossman)
+
 Documentation
 ----------------------
 

solr/contrib/clustering/src/test-files/clustering/solr/conf/solrconfig.xml

@@ -464,10 +464,6 @@
   <!-- config for the admin interface --> 
   <admin>
     <defaultQuery>solr</defaultQuery>
-    
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/contrib/dataimporthandler-extras/src/test-files/dihextras/solr/conf/dataimport-solrconfig.xml

@@ -305,10 +305,6 @@
   <!-- config for the admin interface --> 
   <admin>
     <defaultQuery>*:*</defaultQuery>
-    
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/contrib/dataimporthandler/src/test-files/dih/solr/conf/contentstream-solrconfig.xml

@@ -309,10 +309,6 @@
   <!-- config for the admin interface --> 
   <admin>
     <defaultQuery>*:*</defaultQuery>
-    
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
   <updateRequestProcessorChain key="contentstream" default="true">

solr/contrib/dataimporthandler/src/test-files/dih/solr/conf/dataimport-nodatasource-solrconfig.xml

@@ -307,10 +307,6 @@
   <!-- config for the admin interface --> 
   <admin>
     <defaultQuery>*:*</defaultQuery>
-    
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/contrib/dataimporthandler/src/test-files/dih/solr/conf/dataimport-solrconfig.xml

@@ -305,10 +305,6 @@
   <!-- config for the admin interface --> 
   <admin>
     <defaultQuery>*:*</defaultQuery>
-    
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
   <updateRequestProcessorChain key="dataimport" default="true">

solr/contrib/uima/src/test-files/uima/solr/conf/solrconfig.xml

@@ -968,11 +968,6 @@
   <!-- config for the admin interface -->
   <admin>
     <defaultQuery>*</defaultQuery>
-
-    <!--
-      configure a healthcheck file for servers behind a loadbalancer
-      <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/contrib/uima/src/test-files/uima/uima-tokenizers-solrconfig.xml

@@ -850,11 +850,6 @@
   <!-- config for the admin interface -->
   <admin>
     <defaultQuery>*</defaultQuery>
-
-    <!--
-      configure a healthcheck file for servers behind a loadbalancer
-      <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/core/src/java/org/apache/solr/handler/PingRequestHandler.java

@@ -19,31 +19,155 @@ package org.apache.solr.handler;
 
 import java.io.File;
 import java.io.FileWriter;
-import java.text.SimpleDateFormat;
+import java.io.IOException;
 import java.util.Date;
 import java.util.Locale;
 
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.params.CommonParams;
 import org.apache.solr.common.params.SolrParams;
+import org.apache.solr.common.util.NamedList;
 import org.apache.solr.core.SolrCore;
+import org.apache.solr.util.plugin.SolrCoreAware;
 import org.apache.solr.request.SolrQueryRequest;
 import org.apache.solr.request.SolrRequestHandler;
 import org.apache.solr.response.SolrQueryResponse;
+import org.apache.solr.schema.DateField;
 
+import org.apache.commons.io.FileUtils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
- * Ping solr core
+ * Ping Request Handler for reporting SolrCore health to a Load Balancer.
+ *
+ * <p>
+ * This handler is designed to be used as the endpoint for an HTTP 
+ * Load-Balancer to use when checking the "health" or "up status" of a 
+ * Solr server.
+ * </p>
  * 
+ * <p> 
+ * In it's simplest form, the PingRequestHandler should be
+ * configured with some defaults indicating a request that should be
+ * executed.  If the request succeeds, then the PingRequestHandler
+ * will respond back with a simple "OK" status.  If the request fails,
+ * then the PingRequestHandler will respond back with the
+ * corrisponding HTTP Error code.  Clients (such as load balancers)
+ * can be configured to poll the PingRequestHandler monitoring for
+ * these types of responses (or for a simple connection failure) to
+ * know if there is a problem with the Solr server.
+ * </p>
+ *
+ * <pre class="prettyprint">
+ * &lt;requestHandler name="/admin/ping" class="solr.PingRequestHandler"&gt;
+ *   &lt;lst name="invariants"&gt;
+ *     &lt;str name="qt"&gt;/search&lt;/str&gt;&lt;!-- handler to delegate to --&gt;
+ *     &lt;str name="q"&gt;some test query&lt;/str&gt;
+ *   &lt;/lst&gt;
+ * &lt;/requestHandler&gt;
+ * </pre>
+ *
+ * <p>
+ * A more advanced option available, is to configure the handler with a 
+ * "healthcheckFile" which can be used to enable/disable the PingRequestHandler.
+ * </p>
+ *
+ * <pre class="prettyprint">
+ * &lt;requestHandler name="/admin/ping" class="solr.PingRequestHandler"&gt;
+ *   &lt;!-- relative paths are resolved against the data dir --&gt;
+ *   &lt;str name="healthcheckFile"&gt;server-enabled.txt&lt;/str&gt;
+ *   &lt;lst name="invariants"&gt;
+ *     &lt;str name="qt"&gt;/search&lt;/str&gt;&lt;!-- handler to delegate to --&gt;
+ *     &lt;str name="q"&gt;some test query&lt;/str&gt;
+ *   &lt;/lst&gt;
+ * &lt;/requestHandler&gt;
+ * </pre>
+ *
+ * <ul>
+ *   <li>If the health check file exists, the handler will execute the 
+ *       delegated query and return status as described above.
+ *   </li>
+ *   <li>If the health check file does not exist, the handler will return 
+ *       an HTTP error even if the server is working fine and the delegated 
+ *       query would have succeeded
+ *   </li>
+ * </ul>
+ *
+ * <p> 
+ * This health check file feature can be used as a way to indicate
+ * to some Load Balancers that the server should be "removed from
+ * rotation" for maintenance, or upgrades, or whatever reason you may
+ * wish.  
+ * </p>
+ *
+ * <p> 
+ * The health check file may be created/deleted by any external
+ * system, or the PingRequestHandler itself can be used to
+ * create/delete the file by specifying an "action" param in a
+ * request: 
+ * </p>
+ *
+ * <ul>
+ *   <li><code>http://.../ping?action=enable</code>
+ *       - creates the health check file if it does not already exist
+ *   </li>
+ *   <li><code>http://.../ping?action=disable</code>
+ *       - deletes the health check file if it exists
+ *   </li>
+ *   <li><code>http://.../ping?action=status</code>
+ *       - returns a status code indicating if the healthcheck file exists 
+ *       ("<code>enabled</code>") or not ("<code>disabled<code>")
+ *   </li>
+ * </ul>
+ *
  * @since solr 1.3
  */
-public class PingRequestHandler extends RequestHandlerBase 
+public class PingRequestHandler extends RequestHandlerBase implements SolrCoreAware
 {
+  public static Logger log = LoggerFactory.getLogger(PingRequestHandler.class);
 
-  SimpleDateFormat formatRFC3339 = new SimpleDateFormat("yyyy-MM-dd'T'h:m:ss.SZ");
+  public static final String HEALTHCHECK_FILE_PARAM = "healthcheckFile";
   protected enum ACTIONS {STATUS, ENABLE, DISABLE, PING};
-  private String healthcheck = null;
   
+  private String healthFileName = null;
+  private File healthcheck = null;
+
+  public void init(NamedList args) {
+    super.init(args);
+    Object tmp = args.get(HEALTHCHECK_FILE_PARAM);
+    healthFileName = (null == tmp ? null : tmp.toString());
+  }
+
+  public void inform( SolrCore core ) {
+    if (null != healthFileName) {
+      healthcheck = new File(healthFileName);
+      if ( ! healthcheck.isAbsolute()) {
+        healthcheck = new File(core.getDataDir(), healthFileName);
+        healthcheck = healthcheck.getAbsoluteFile();
+      }
+
+      if ( ! healthcheck.getParentFile().canWrite()) {
+        // this is not fatal, users may not care about enable/disable via 
+        // solr request, file might be touched/deleted by an external system
+        log.warn("Directory for configured healthcheck file is not writable by solr, PingRequestHandler will not be able to control enable/disable: {}",
+                 healthcheck.getParentFile().getAbsolutePath());
+      }
+
+    }
+    
+  }
+  
+  /**
+   * Returns true if the healthcheck flag-file is enabled but does not exist, 
+   * otherwise (no file configured, or file configured and exists) 
+   * returns false. 
+   */
+  public boolean isPingDisabled() {
+    return (null != healthcheck && ! healthcheck.exists() );
+  }
+
   @Override
   public void handleRequestBody(SolrQueryRequest req, SolrQueryResponse rsp) throws Exception 
   {
@@ -51,9 +175,6 @@ public class PingRequestHandler extends RequestHandlerBase
     SolrParams params = req.getParams();
     SolrCore core = req.getCore();
     
-    // Check if the service is available
-    healthcheck = core.getSolrConfig().get("admin/healthcheck/text()", null );
-    
     String actionParam = params.get("action");
     ACTIONS action = null;
     if (actionParam == null){
@@ -70,32 +191,28 @@ public class PingRequestHandler extends RequestHandlerBase
     }
     switch(action){
       case PING:
-        if( healthcheck != null && !new File(healthcheck).exists() ) {
+        if( isPingDisabled() ) {
-          throw new SolrException(SolrException.ErrorCode.SERVICE_UNAVAILABLE, "Service disabled");
+          throw new SolrException(SolrException.ErrorCode.SERVICE_UNAVAILABLE, 
+                                  "Service disabled");
         }
         handlePing(req, rsp);
         break;
       case ENABLE:
-        handleEnable(healthcheck,true);
+        handleEnable(true);
         break;
       case DISABLE:
-        handleEnable(healthcheck,false);
+        handleEnable(false);
         break;
       case STATUS:
-        if( healthcheck == null){
+        if( healthcheck == null ){
-          SolrException e = new SolrException(SolrException.ErrorCode.SERVICE_UNAVAILABLE, "healthcheck not configured");
+          SolrException e = new SolrException
+            (SolrException.ErrorCode.SERVICE_UNAVAILABLE, 
+             "healthcheck not configured");
           rsp.setException(e);
-        }
+        } else {
-        else {
+          rsp.add( "status", isPingDisabled() ? "disabled" : "enabled" );      
-          if ( new File(healthcheck).exists() ){
-            rsp.add( "status",  "enabled");      
-          }
-          else {
-            rsp.add( "status",  "disabled");      
-          }
         }
     }
-
   }
   
   protected void handlePing(SolrQueryRequest req, SolrQueryResponse rsp) throws Exception
@@ -136,24 +253,25 @@ public class PingRequestHandler extends RequestHandlerBase
     rsp.add( "status", "OK" );
   }
   
-  protected void handleEnable(String healthcheck, boolean enable) throws Exception
+  protected void handleEnable(boolean enable) throws SolrException {
-  {
     if (healthcheck == null) {
       throw new SolrException(SolrException.ErrorCode.SERVICE_UNAVAILABLE, 
         "No healthcheck file defined.");
     }
-    File enableFile = new File(healthcheck);
     if ( enable ) {
-      enableFile.createNewFile();
+      try {
-      
+        // write out when the file was created
-      // write out when the file was created
+        FileUtils.write(healthcheck, 
-      FileWriter fw = new FileWriter(enableFile);      
+                        DateField.formatExternal(new Date()), "UTF-8");
-      fw.write(formatRFC3339.format(new Date()));
+      } catch (IOException e) {
-      fw.close(); 
+        throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, 
-      
+                                "Unable to write healthcheck flag file", e);
+      }
     } else {
-      if (enableFile.exists() && !enableFile.delete()){
+      if (healthcheck.exists() && !healthcheck.delete()){
-        throw new SolrException( SolrException.ErrorCode.NOT_FOUND,"Did not successfully delete healthcheck file:'"+healthcheck+"'");
+        throw new SolrException(SolrException.ErrorCode.NOT_FOUND,
+                                "Did not successfully delete healthcheck file: "
+                                +healthcheck.getAbsolutePath());
       }
     }
   }

solr/core/src/test/org/apache/solr/handler/PingRequestHandlerTest.java

@@ -20,21 +20,24 @@ package org.apache.solr.handler;
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
+import java.io.IOException;
 
 import org.apache.solr.SolrTestCaseJ4;
 import org.apache.solr.common.SolrException;
+import org.apache.solr.common.util.NamedList;
 import org.apache.solr.request.SolrQueryRequest;
 import org.apache.solr.response.SolrQueryResponse;
+
+import org.apache.commons.io.FileUtils;
+
 import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Ignore;
-import org.junit.Test;
-
 
 public class PingRequestHandlerTest extends SolrTestCaseJ4 {
 
-  private String healthcheck = "server-enabled";
+  private final String fileName = this.getClass().getName() + ".server-enabled";
-  private File healthcheckFile = new File(healthcheck);
+  private File healthcheckFile = null;
   private PingRequestHandler handler = null;
   
   @BeforeClass
@@ -43,116 +46,149 @@ public class PingRequestHandlerTest extends SolrTestCaseJ4 {
   }
 
   @Before
-  public void before() {
+  public void before() throws IOException {
-    healthcheckFile.delete();
-    handler = new PingRequestHandler();
-  }
-  
-  @Test
-  public void testPing() throws Exception {
-     
-    SolrQueryRequest req = req();
-    SolrQueryResponse rsp = new SolrQueryResponse();
-    
-    handler.handleRequestBody(req, rsp);
-    String status = (String) rsp.getValues().get("status");
-    assertEquals("OK", status);
-    req.close();
-    
-    req = req("action","ping");
-    rsp = new SolrQueryResponse();
-    
-    handler.handleRequestBody(req, rsp);
-    status = (String) rsp.getValues().get("status");
-    assertEquals("OK", status);
-    req.close();    
-  }
-  
-  @Test
-  public void testEnablingServer() throws Exception {
-    
-        
-    handler.handleEnable(healthcheck, true);
-    
-    assertTrue(healthcheckFile.exists());
-    
-    SolrQueryRequest req = req();
-    SolrQueryResponse rsp = new SolrQueryResponse();
 
-    handler.handlePing(req, rsp);
+    // by default, use relative file in dataDir
-    String status = (String) rsp.getValues().get("status");
+    healthcheckFile = new File(dataDir, fileName);
-    assertEquals("OK", status);
+    String fileNameParam = fileName;
-    req.close();
+
-    
+    // sometimes randomly use an absolute File path instead 
-    FileReader fr = new FileReader(healthcheckFile);
+    if (random().nextBoolean()) {
-  
+      healthcheckFile = new File(TEMP_DIR, fileName);
-    BufferedReader br = new BufferedReader(fr); 
+      fileNameParam = healthcheckFile.getAbsolutePath();
-    String s = br.readLine();
+    } 
-    assertNotNull(s);
+      
-     
+    if (healthcheckFile.exists()) FileUtils.forceDelete(healthcheckFile);
+
+    handler = new PingRequestHandler();
+    NamedList initParams = new NamedList();
+    initParams.add(PingRequestHandler.HEALTHCHECK_FILE_PARAM,
+                   fileNameParam);
+    handler.init(initParams);
+    handler.inform(h.getCore());
   }
   
-  @Test
+  public void testPingWithNoHealthCheck() throws Exception {
-  public void testDisablingServer() throws Exception {
     
+    // for this test, we don't want any healthcheck file configured at all
+    handler = new PingRequestHandler();
+    handler.init(new NamedList());
+    handler.inform(h.getCore());
+
+    SolrQueryResponse rsp = null;
+    
+    rsp = makeRequest(handler, req());
+    assertEquals("OK", rsp.getValues().get("status"));
+    
+    rsp = makeRequest(handler, req("action","ping"));
+    assertEquals("OK", rsp.getValues().get("status")); 
+
+  }
+  
+  public void testEnablingServer() throws Exception {
+
+    assertTrue(! healthcheckFile.exists());
+
+    // first make sure that ping responds back that the service is disabled
+
+    try {
+      makeRequest(handler, req());
+      fail("Should have thrown a SolrException because not enabled yet");
+    } catch (SolrException se){
+      assertEquals(SolrException.ErrorCode.SERVICE_UNAVAILABLE.code,se.code());
+    }
+
+    // now enable
+
+    makeRequest(handler, req("action", "enable"));
+
+    assertTrue(healthcheckFile.exists());
+    assertNotNull(FileUtils.readFileToString(healthcheckFile), "UTF-8");
+
+    // now verify that the handler response with success
+
+    SolrQueryResponse rsp = makeRequest(handler, req());
+    assertEquals("OK", rsp.getValues().get("status"));
+
+    // enable when already enabled shouldn't cause any problems
+    makeRequest(handler, req("action", "enable"));
+    assertTrue(healthcheckFile.exists());
+
+  }
+  
+  public void testDisablingServer() throws Exception {
+
+    assertTrue(! healthcheckFile.exists());
         
     healthcheckFile.createNewFile();
+
+    // first make sure that ping responds back that the service is enabled
+
+    SolrQueryResponse rsp = makeRequest(handler, req());
+    assertEquals("OK", rsp.getValues().get("status"));
+
+    // now disable
     
-    handler.handleEnable(healthcheck, false);
+    makeRequest(handler, req("action", "disable"));
     
     assertFalse(healthcheckFile.exists());
 
+    // now make sure that ping responds back that the service is disabled
+
+    try {
+      makeRequest(handler, req());
+      fail("Should have thrown a SolrException because not enabled yet");
+    } catch (SolrException se){
+      assertEquals(SolrException.ErrorCode.SERVICE_UNAVAILABLE.code,se.code());
+    }
+    
+    // disable when already disabled shouldn't cause any problems
+    makeRequest(handler, req("action", "disable"));
+    assertFalse(healthcheckFile.exists());
     
   }
+
   
-  @Test
-  @Ignore // because of how we load the healthcheck file, we have to change it in schema.xml
   public void testGettingStatus() throws Exception {
+    SolrQueryResponse rsp = null;
+
+    handler.handleEnable(true);
     
-        
+    rsp = makeRequest(handler, req("action", "status"));
-    handler.handleEnable(healthcheck, true);
+    assertEquals("enabled", rsp.getValues().get("status"));
-    
-    
-    SolrQueryRequest req = req("action", "status");
-    SolrQueryResponse rsp = new SolrQueryResponse();
-        
-    handler.handleRequestBody(req, rsp);
-    
-    String status = (String) rsp.getValues().get("status");
-    assertEquals("enabled", status);
-    
-    req.close();    
  
-    handler.handleEnable(healthcheck, false);   
+    handler.handleEnable(false);   
     
-    req = req("action", "status");
+    rsp = makeRequest(handler, req("action", "status"));
-    rsp = new SolrQueryResponse();
+    assertEquals("disabled", rsp.getValues().get("status"));
-    
-    handler.handleRequestBody(req, rsp);
-        
-    status = (String) rsp.getValues().get("status");
-    assertEquals("disabled", status);
-       
-    req.close();    
  
   }
   
-  @Test
   public void testBadActionRaisesException() throws Exception {
     
-    SolrQueryRequest req = req("action", "badaction");
-    SolrQueryResponse rsp = new SolrQueryResponse();
-    
     try {
-      handler.handleRequestBody(req, rsp);
+      SolrQueryResponse rsp = makeRequest(handler, req("action", "badaction"));
       fail("Should have thrown a SolrException for the bad action");
-    }
+    } catch (SolrException se){
-    catch (SolrException se){
       assertEquals(SolrException.ErrorCode.BAD_REQUEST.code,se.code());
     }
-
-    req.close();    
-    
   }
-  
+
+  /**
+   * Helper Method: Executes the request against the handler, returns 
+   * the response, and closes the request.
+   */
+  private SolrQueryResponse makeRequest(PingRequestHandler handler,
+                                        SolrQueryRequest req) 
+    throws Exception {
+
+    SolrQueryResponse rsp = new SolrQueryResponse();
+    try {
+      handler.handleRequestBody(req, rsp);
+    } finally {
+      req.close();
+    }
+    return rsp;
+  }
+
 }

solr/example/example-DIH/solr/db/conf/solrconfig.xml

@@ -488,10 +488,6 @@
   <!-- config for the admin interface --> 
   <admin>
     <defaultQuery>*:*</defaultQuery>
-    
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/example/example-DIH/solr/mail/conf/solrconfig.xml

@@ -674,10 +674,6 @@
   <!-- config for the admin interface -->
   <admin>
     <defaultQuery>solr</defaultQuery>
-
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/example/example-DIH/solr/rss/conf/solrconfig.xml

@@ -487,10 +487,6 @@
   <!-- config for the admin interface --> 
   <admin>
     <defaultQuery>*:*</defaultQuery>
-    
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/example/example-DIH/solr/solr/conf/solrconfig.xml

@@ -486,10 +486,6 @@
   <!-- config for the admin interface --> 
   <admin>
     <defaultQuery>*:*</defaultQuery>
-    
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/example/example-DIH/solr/tika/conf/solrconfig.xml

@@ -311,10 +311,6 @@
   <!-- config for the admin interface --> 
   <admin>
     <defaultQuery>*:*</defaultQuery>
-    
-    <!-- configure a healthcheck file for servers behind a loadbalancer
-    <healthcheck type="file">server-enabled</healthcheck>
-    -->
   </admin>
 
 </config>

solr/example/solr/conf/solrconfig.xml

@@ -1064,6 +1064,12 @@
     <lst name="defaults">
       <str name="echoParams">all</str>
     </lst>
+    <!-- An optional feature of the PingRequestHandler is to configure the 
+         handler with a "healthcheckFile" which can be used to enable/disable 
+         the PingRequestHandler.
+         relative paths are resolved against the data dir 
+      -->
+    <!-- <str name="healthcheckFile">server-enabled.txt</str> -->
   </requestHandler>
 
   <!-- Echo the request contents back to the client -->
@@ -1683,13 +1689,6 @@
   <!-- Legacy config for the admin interface -->
   <admin>
     <defaultQuery>*:*</defaultQuery>
-
-    <!-- configure a healthcheck file for servers behind a
-         loadbalancer 
-      -->
-    <!--
-       <healthcheck type="file">server-enabled</healthcheck>
-      -->
   </admin>
 
 </config>