Tomcat is a popular open source implementation of the Java Servlet specification. For more information visit tomcat.apache.org.
Even if the Tomcat plugin is not configured, Monitoring will discover Tomcat services as a webserver.
The services discovered are displayed on the Tomcat Services page in the Resources menu. After you install the monitoring agent and configure the Tomcat plugin on your instances, Monitoring populates the Tomcat Services page with inventory and metrics.
Configuring Monitoring to monitor Tomcat
After you install the monitoring agent,
use the following instructions to configure the Tomcat plugin on your instances.
For instructions on upgrading from the legacy
jmxtrans monitoring, see
Upgrading from jmxtrans below.
The Tomcat plugin requires version 5.5.0-257 or later of the monitoring agent. To update the agent, see Upgrading the agent.
Tomcat must be set to enable external JMX monitoring. See the JMX documentation at tomcat.apache.org.
Enabling the Tomcat monitoring plugin
Tomcat is monitored via JMX. Monitoring supports monitoring Tomcat version 7. Tomcat version 8 is not currently supported.
(cd /opt/stackdriver/collectd/etc/collectd.d/ && curl -O https://raw.githubusercontent.com/Stackdriver/stackdriver-agent-service-configs/master/etc/collectd.d/tomcat-7.conf)
The downloaded plugin configuration file assumes that your Tomcat instance is configured to accept JMX connections on port 9012. If you have configured Tomcat with a different JMX port, edit the file and follow the instructions to change the JMX port settings.
After adding the configuration file, restart the monitoring agent by running the following command:
sudo service stackdriver-agent restart
Information on other plugin configuration options can be found at collectd.org.
What is monitored
The Tomcat plugin monitors the following metrics:
- Threads: Total and busy threads in the Tomcat process.
- Requests: The number of completed and error requests that took place.
- Sessions: How many sessions are active in Tomcat.
Monitoring also monitors the following basic JVM metrics:
- Active JVM Threads
- JVM Heap memory usage
- JVM Non-Heap memory usage
- JVM Open File Descriptors
- JVM Garbage Collection Count
Upgrading from jmxtrans
If you are currently running a VM with the legacy
you need to upgrade all of the Java-based plugins, namely
Tomcat. After you've upgraded those plugins
and restarted the
stackdriver-agent service, you can shut down the
process. You can then uninstall
jmxtrans by removing the
tree and the
/etc/init.d/jmxtrans script (if the script is present).