Apache Tomcat 8

• Introduction
• Enabling JMX Remote
• Manage Tomcat with JMX remote Ant Tasks
• JMXAccessorOpenTask - JMX open connection task
• JMXAccessorGetTask: get attribute value Ant task
• JMXAccessorSetTask: set attribute value Ant task
• JMXAccessorInvokeTask: invoke MBean operation Ant task
• JMXAccessorQueryTask: query MBean Ant task
• JMXAccessorCreateTask: remote create MBean Ant task
• JMXAccessorUnregisterTask: remote unregister MBean Ant task
• JMXAccessorCondition: express condition
• JMXAccessorEqualsCondition: equals MBean Ant condition
• Using the JMXProxyServlet

Monitoring is a key aspect of system administration. Looking inside a running server, obtaining some statistics or reconfiguring some aspects of an application are all daily administration tasks.

Note: This configuration is needed only if you are going to monitor Tomcat remotely. It is not needed if you are going to monitor it locally, using the same user that Tomcat runs with.

The Oracle website includes the list of options and how to configure JMX Remote on Java 8: http://docs.oracle.com/javase/6/docs/technotes/guides/management/agent.html.

The following is a quick configuration guide for Java 8:

Add the following parameters to setenv.bat script of your Tomcat (see RUNNING.txt for details).
Note: This syntax is for Microsoft Windows. The command has to be on the same line. It is wrapped to be more readable. If Tomcat is running as a Windows service, use its configuration dialog to set java options for the service. For Linux, MacOS, etc, remove "set " from beginning of the line.

set CATALINA_OPTS=-Dcom.sun.management.jmxremote.port=%my.jmx.port%
  -Dcom.sun.management.jmxremote.rmi.port=%my.rmi.port%
  -Dcom.sun.management.jmxremote.ssl=false
  -Dcom.sun.management.jmxremote.authenticate=false

If you don't set com.sun.management.jmxremote.rmi.port then the JSR 160 JMX-Adaptor will select a port at random which will may it difficult to configure a firewall to allow access.

If you require TLS:

1. change and add this:

     -Dcom.sun.management.jmxremote.ssl=true
     -Dcom.sun.management.jmxremote.registry.ssl=true
   

2. to configure the protocols and/or cipher suites use:

     -Dcom.sun.management.jmxremote.ssl.enabled.protocols=%my.jmx.ssl.protocols%
     -Dcom.sun.management.jmxremote.ssl.enabled.cipher.suites=%my.jmx.cipher.suites%
   

3. to client certificate authentication use:

     -Dcom.sun.management.jmxremote.ssl.need.client.auth=%my.jmx.ssl.clientauth%

If you require authorization (it is strongly recommended that TLS is always used with authentication):

1. change and add this:

     -Dcom.sun.management.jmxremote.authenticate=true
     -Dcom.sun.management.jmxremote.password.file=../conf/jmxremote.password
     -Dcom.sun.management.jmxremote.access.file=../conf/jmxremote.access

2. edit the access authorization file $CATALINA_BASE/conf/jmxremote.access:

   monitorRole readonly
   controlRole readwrite

3. edit the password file $CATALINA_BASE/conf/jmxremote.password:

   monitorRole tomcat
   controlRole tomcat

   Tip: The password file should be read-only and only accessible by the operating system user Tomcat is running as.
4. Alternatively, you can configure a JAAS login module with:

     -Dcom.sun.management.jmxremote.login.config=%login.module.name%

If you need to specify a host name to be used in the RMI stubs sent to the client (e.g. because the public host name that must be used to connect is not the same as the local host name) then you can set:

set CATALINA_OPTS=-Djava.rmi.server.hostname

If you need to specify a specific interface for the JMX service to bind to then you can set:

set CATALINA_OPTS=-Dcom.sun.management.jmxremote.host

To simplify JMX usage with Ant, a set of tasks is provided that may be used with antlib.

antlib: Copy your catalina-ant.jar from $CATALINA_HOME/lib to $ANT_HOME/lib.

The following example shows the JMX Accessor usage:
Note: The name attribute value was wrapped here to be more readable. It has to be all on the same line, without spaces.

  
  
  
  

  
    
    
    
    
    
    
    
    
    
    
    
      
      
    
    
    
    

senderObjectNames: ${senderObjectNames.0}
IDataSender.backup.connected: ${IDataSender.backup.connected}
session: ${sessions.0}
manager.length: ${manager.length}
manager.0.name: ${manager.0.name}
manager.1.name: ${manager.1.name}
hello: ${Hello}
manager.ClusterTest.0.name: ${manager.ClusterTest.0.name}
manager.ClusterTest.0.activeSessions: ${manager.ClusterTest.0.activeSessions}
manager.ClusterTest.0.counterSend_EVT_SESSION_EXPIRED:
 ${manager.ClusterTest.0.counterSend_EVT_SESSION_EXPIRED}
manager.ClusterTest.0.counterSend_EVT_GET_ALL_SESSIONS:
 ${manager.ClusterTest.0.counterSend_EVT_GET_ALL_SESSIONS}


  

import: Import the JMX Accessor Project with and reference the tasks with jmxOpen, jmxSet, jmxGet, jmxQuery, jmxInvoke, jmxEquals and jmxCondition.

List of Attributes

Example to open a new JMX connection

Example to open a JMX connection from URL, with authorization and store at other reference

Example to open a JMX connection from URL, with authorization and store at other reference, but only when property jmx.if exists and jmx.unless not exists

Note: All properties from jmxOpen task also exists at all other tasks and conditions.

List of Attributes

Example to get remote MBean attribute from default JMX connection

Example to get and result array and split it at separate properties

Access the senderObjectNames properties with:

  ${senderObjectNames.length} give the number of returned sender list.
  ${senderObjectNames.[0..N]} found all sender object names

Example to get IDataSender attribute connected only when cluster is configured.
Note: The name attribute value was wrapped here to be more readable. It has to be all on the same line, without spaces.

List of Attributes

Example to set remote MBean attribute value

List of Attributes

stop an application

Now you can find the sessionid at ${sessions.[0..N} properties and access the count with ${sessions.length} property.

Example to get all sessionids

Now you can find the sessionid at ${sessions.[0..N} properties and access the count with ${sessions.length} property.

Example to get remote MBean session attribute from session ${sessionid.0}

Example to create a new access logger valve at vhost localhost

Now you can find new MBean with name stored at ${accessLoggerObjectName} property.

List of Attributes

Get all Manager ObjectNames from all services and Hosts

Now you can find the Session Manager at ${manager.[0..N].name} properties and access the result object counter with ${manager.length} property.

Example to get the Manager from servlet-examples application an bind all MBean properties

Now you can find the manager at ${manager.servletExamples.0.name} property and can access all properties from this manager with ${manager.servletExamples.0.[manager attribute names]}. The result object counter from MBeans is stored ad ${manager.length} property.

Example to get all MBeans from a server and store inside an external XML property file

Now you can find all MBeans inside the file mbeans.properties.

List of Attributes

Example to create remote MBean

Warning: Many Tomcat MBeans can't be linked to their parent once
created. The Valve, Cluster and Realm MBeans are not automatically
connected with their parent. Use the MBeanFactory create
operation instead.

List of Attributes

Example to unregister remote MBean

Warning: A lot of Tomcat MBeans can't be unregister.
The MBeans are not unlinked from their parent. Use MBeanFactory
remove operation instead.

List of Attributes

Wait for server connection and that cluster backup node is accessible

List of Attributes

Wait for server connection and that cluster backup node is accessible

Tomcat offers an alternative to using remote (or even local) JMX connections while still giving you access to everything JMX has to offer: Tomcat's JMXProxyServlet.

The JMXProxyServlet allows a client to issue JMX queries via an HTTP interface. This technique offers the following advantages over using JMX directly from a client program:

• You don't have to launch a full JVM and make a remote JMX connection just to ask for one small piece of data from a running server
• You don't have to know how to work with JMX connections
• You don't need any of the complex configuration covered in the rest of this page
• Your client program does not have to be written in Java

A perfect example of JMX overkill can be seen in the case of popular server-monitoring software such as Nagios or Icinga: if you want to monitor 10 items via JMX, you will have to launch 10 JVMs, make 10 JMX connections, and then shut them all down every few minutes. With the JMXProxyServlet, you can make 10 HTTP connections and be done with it.

You can find out more information about the JMXProxyServlet in the documentation for the Tomcat manager.