Monitoring Apache Tomcat Servers With Nagios XI

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1 Purpose This document describes how to add custom Apache Tomcat plugins and checks, namely check_tomcatsessions, to your server. Implementing Apache Tomcat plugins within will allow you the to monitor the health and vital statistics of your Apache Tomcat systems. Target Audience This document is intended for use by administrators who are responsible for monitoring Apache Tomcat servers. What Is Apache Tomcat? Apache Tomcat is an open source web server and servlet container developed by the Apache Software Foundation. Tomcat implements the Java Servlet and the JavaServer Pages specifications from Sun Microsystems, and provides a "pure Java" HTTP web server environment for Java code to run in Prerequisites Apache Tomcat (6, 7, 8, or 9) server Access to a user who is assigned the role manager-script If you need assistance adding a new user such as nagios to the Tomcat server with the above roles please reference A recent version of the check_tomcatsessions plugin installed on your Nagios server steps provided below A network route from your Nagios server to the Tomcat server Page 1 / 10

2 Installing Tomcat Plugin You will need to download the plugin check_tomcatsessions from the Nagios Exchange, which can be downloaded from the following location: Tomcat/check_tomcatSessions/details The download will be a zip file and inside that file will be the check_tomcatsessions plugin. To upload the file to the server, open the web interface and navigate to Admin > System Extensions > Manage Plugins. Use the Browse and Upload Plugin buttons to upload the check_tomcatsessions plugin. More information on managing plugins in can be found in the following documentation: Managing Plugins In Now that you have installed the Tomcat plugin, the next step is to proceed to executing the check from the command line of your server. We do this to verify the plugin is working before moving on to integrating it within. Executing check_tomcatsessions From The Command Line You should now have the check_tomcatsessions plugin on your Nagios server in your plugins directory (/usr/local/nagios/libexec/). Establish a terminal session to your server as the root user and change into that directory: cd /usr/local/nagios/libexec/ Begin by executing the plugin with the -h flag. Most Nagios plugins provide this flag to outline the command line options so you can sculpt your remote host check../check_tomcatsessions -h Page 2 / 10

3 You should see output similar to: Usage: check_tomcatsessions [ -H hostname or IP address ] [ -P port ] [ -u username ] [ -p password ] [ -s session_name ] [ -w warning ] [ -c critical ] [ -V tomcat_version (6 for tomcat pre-7 or 7) ] If session_name is omitted (default) then the total number of sessions is calculated DEFAULTS hostname=localhost port=8080 username=administrator password=password session_name= warning=100 critical=400 tomcat_version=6 The above tells us we need to provide the following arguments: -H = Address of Tomcat server, this example will use P = Port the Tomcat server is listening on, this example will use u = Username to access the Tomcat server, this example will use nagios -p = Password for the username, this example will use nagiosxi -s = The session name to check, this example will use manager -w = The warning threshold, this example will use 10 -c = The critical threshold, this example will use 40 -V = The Tomcat version, this example will use 7 Page 3 / 10

4 Here is the command with all those arguments:./check_tomcatsessions -H P u nagios -p nagiosxi -s manager -w 10 -c 40 -V 7 The output for this command will look similar to: Tomcat sessions manager OK: 4 sessions=4 The above tells us the manager session is in an OK state, because only 4 sessions are running at this time. Implement Check in Nagios Now that you have tested the check_tomcatsessions plugin and it is running successfully from the command line and returning valid information, you can move on to integrating this check with. This is done by: Create a command definition for the check_tomcatsessions plugin Creating a host object for your Tomcat server Create a service that uses the newly created command Seeing as Apache Tomcat is a web server, the Website Wizard will be used to create the host object, using a wizard makes it easy. Page 4 / 10

5 Create Command Definition To create a command within, navigate to Configure > Core Config Manager > Commands > >_Commands. Click the Add New button. Create the command using the information as follows: Command Name: check_tomcatsessions Command Line: $USER1$/check_tomcatSessions -H $HOSTNAME$ $ARG1$ Command Type: check command Click the Save button and then Apply Configuration. Page 5 / 10

6 Create Tomcat Server Host Object: As mentioned earlier, using the Website Wizard will make this step easy. Navigate via the top menu bar to Configure > Run a configuration wizard and select the Website wizard from the list. In the screenshot on the following page you can see how the search field allows you to quickly find a wizard. On Step 1 enter the URL to your Tomcat server, in this example it is Click Next to continue to Step 2. Page 6 / 10

7 Step 2 is where you define the monitoring options. For this example, the only options defined were: Host Name This is the name the host will be given in. Under Website Services the HTTP service has been selected. After the wizard has created this service you'll go into Core Configuration Manager (CCM) and change this service so it performs the Apache Tomcat check. Click Next and then complete the wizard by choosing the required options in Step 3 Step 5. To finish up, click on Finish in the final step of the wizard. After the wizard has completed, navigate to Configure > Core Config Manager > Monitoring > Hosts. Click the Edit icon in the actions column to begin editing the new Tomcat host. Page 7 / 10

8 In the Check command drop down list select check-host-alive. You need to choose this command as the Tomcat server by default doesn't listen on Port 80, so the host will appear as down. Assuming your Tomcat server responds to ping checks the check-host-alive command will ensure the host appears as up. Click the Save button. There's no need to apply configuration right now, proceed to the next step. Define Tomcat Service: Now you need to correctly define the Tomcat service. Navigate to Configure > Core Config Manager > Monitoring > Services. Page 8 / 10

9 Use the Config Name drop down list to select the new Tomcat host, this will display the new HTTP service. Click the Edit icon in the actions column to begin editing the service. Change the Description to Tomcat Sessions. In the Check command drop down list select check_tomcatsessions. Enter the following into the $ARG1$ field (replace the existing text in this field:) -P u nagios -p nagiosxi -s manager -w 10 -c 40 -V 7 You can continue to configure the service object as you normally would using templates, check,alert and misc. settings. Using the Configuration Wizard to create this service means that there isn't anything else you need to do. Click the Save button. Apply Configuration to start monitoring the new service. Page 9 / 10

10 The check should now be active and working. From the navigation menu search for Tomcat and your new host and service will appear with it's current state. Finishing Up This completes the documentation on monitoring Apache Tomcat servers in. If you have additional questions or other support related questions, please visit us at our Nagios Support Forums: The Nagios Support Knowledgebase is also a great support resource: Page 10 / 10