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JMX Monitoring

Video Lecture

Configure JMX Monitoring in Zabbix

Description

JMX stands for Java Management Extensions. It is a framework for monitoring Java processes, and we can configure Zabbix to connect to a running JMX daemon thread.

To demonstrate, I will install a basic setup of Tomcat server on an Ubuntu 22.04 and enable it to be monitored using JMX.

On the server where you want to run Tomcat, create a separate unprivileged user to run it. I named my user tomcat.

sudo useradd -m -d /opt/tomcat -U -s /bin/false tomcat

Update the package manager cache.

sudo apt update

Install the JDK

sudo apt install default-jdk

Check that Java is working

java -version

The response will be similar to

openjdk version "11.0.16" 2022-07-19
OpenJDK Runtime Environment (build 11.0.16+8-post-Ubuntu-0ubuntu122.04)
OpenJDK 64-Bit Server VM (build 11.0.16+8-post-Ubuntu-0ubuntu122.04, mixed mode, sharing)

Now download the Tomcat core. I downloaded 10.0.23.

wget https://dlcdn.apache.org/tomcat/tomcat-10/v10.0.23/bin/apache-tomcat-10.0.23.tar.gz

Extract the downloaded file

sudo tar xzvf apache-tomcat-10.0.23.tar.gz -C /opt/tomcat --strip-components=1

Grant your tomcat user ownership of the folder where the tar was extracted

sudo chown -R tomcat:tomcat /opt/tomcat/

And make the files executable

sudo chmod -R u+x /opt/tomcat/bin

CD into it and check

cd /opt/tomcat/bin
ls -lh

Start the Tomcat web server.

./catalina.sh start

Visit it in your browser

http://[IP address of server running Tomcat]:8080

You should see the Tomcat homepage.

Now we need to modify the configuration to enable the inbuilt JMX daemon to return its monitoring data.

In the same folder at /opt/tomcat/bin, we create a new file named setenv.sh

sudo nano setenv.sh

Copy and paste the text,

CATALINA_OPTS="-Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=9000 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Djava.rmi.server.hostname=[IP address of server running Tomcat]"

Note the option -Djava.rmi.server.hostname=. This is needed for remote connections. If you are connecting to the JMX daemon locally only, then you can omit this parameter.

Also replace the text [IP address of server running Tomcat] with the IP address of your server where you just installed Tomcat.

I have put my Tomcat servers external IP address, since I will be monitoring it remotely from my Zabbix server.

Save by pressing CTRL-X then Y

Check setenv.sh now exists in the folder

ls -lh

Also make the setenv.sh file executable

chmod 750 setenv.sh

Check it again

ls -lh

Change the setenv.sh file owner to tomcat:tomcat

sudo chown -R tomcat:tomcat setenv.sh

And check again

ls -lh

Now we can restart Tomcat

./catalina.sh stop
./catalina.sh start

We should now see the CATALINA_OPTS in the response showing our JMX configuration.

We can check if port 9000 is open to connections.

ss -ntlp | grep 9000

Now to set up Zabbix.

SSH onto your Zabbix server and check if we can telnet to port 9000 on our tomcat servers external IP address.

telnet [IP address of server running Tomcat] 9000

Next to create a JMX host in Zabbix.

I am going to assign the Apache Tomcat by JMX template.

Create the host and name it what you want.

You will find the Apache Tomcat by JMX template in the Templates/Applications host group.

Add the host to any group.

Add the JMX interface.

Set the IP address that Zabbix server (or proxy if host is monitored by proxy) will use to find it.

Set the port to 9000.

We can do various tests to see if it's working. It will not be. There are several more things to do.

We need to install the Java gateway on our Zabbix server, or Zabbix proxy if the host will be monitored by proxy.

sudo apt install zabbix-java-gateway

The Zabbix Java Gateway has its own configuration file. We can leave the defaults. You can view it using,

sudo nano /etc/zabbix/zabbix_java_gateway.conf

Next to update Zabbix servers (or Zabbix proxy) configuration to point to the Java gateway.

sudo nano /etc/zabbix/zabbix_server.conf

Uncomment and change parameters,

JavaGateway=127.0.0.1
JavaGatewayPort=10052
StartJavaPollers=5

Restart the Zabbix server (or proxy if using the Zabbix proxy)

sudo service zabbix-server restart

Do some tests, and run execute now on the items and discovery rules. The JMX icon should light up green, and there will be data in the MonitoringLatest Data page.

Troubleshooting

Your problems are likely to be firewall, user permissions, JMX daemon related or Zabbix server/proxy configuration. You need to recheck everything.

Java Gateway Configuration Parameter not Set or Empty

You need to install the Zabbix Java Gateway process and set the Zabbix server configuration to point to it. See instructions above.

jmxterm

You can also test independently of Zabbix if the JMX daemon is actually responding, via a shell program called jmxterm.

Furthermore, you can install this on the server running the JMX daemon to test it locally, or on a remote server, such as your Zabbix server or Zabbix proxy where you can also test it from.

Download jmxterm from its official repository at https://github.com/jiaqi/jmxterm

wget https://github.com/jiaqi/jmxterm/releases/download/v1.0.1/jmxterm-1.0.1-uber.jar

Start jmxterm using Java:

java -jar jmxterm-1.0.1-uber.jar

Open a local JMX connection

$>open localhost:9000

or open a remote JMX connection

$>open <IP Address of Server exposing JMX daemon port>:9000

It should respond that the connection is opened, otherwise it will display some kind of error.

Now run some tests

$>beans
$>get -b NIO:name=accepted,type=total *
$>get -b java.lang:type=Memory *
$>get -b NIO:name=accepted,type=total *

Official JMX Monitoring Documentation

Debian/Ubuntu Java Gateway Install Instructions

Install Apache Tomcat

Configure JMX for Apache Tomcat

jmxterm