Configuring Zabbix server for use with Java gateway
---------------------------------------------------

Zabbix server need to be configured for zabbix-java-gateway.
In the "/etc/zabbix/zabbix_server.conf" make sure to
edit the following keys:

    JavaGateway
    JavaGatewayPort     # if port is not 10052
    StartJavaPollers

In frontend add JMX interface with port of a monitored
Java/JMX service, it is NOT a port 10052.


Debugging Java gateway
----------------------

In case there are any problems with Java gateway or an error message
that you see about an item in the frontend is not descriptive enough,
you might wish to increase logging verbosity. This can be done
by replacing

    <root level="info">

with

    <root level="debug">

in "/etc/zabbix/zabbix_java_gateway.logback.xml".

Note that unlike Zabbix server or Zabbix proxy, there is no need to restart
Zabbix Java gateway after changing logback.xml file - changes in
logback.xml will be picked up automatically. When you are done
with debugging, you can return the logging level to "info".


Configuring monitored host
--------------------------

Use "Template_JMX_Generic" or "Template_JMX_Tomcat".

Sample key:

    jmx["java.lang:type=Memory","HeapMemoryUsage.used"]

Read more:

    https://www.zabbix.com/documentation/6.0/manual/config/items/itemtypes/jmx_monitoring


Monitoring Java applications
----------------------------

As a bare minimum, if you just wish to get started by monitoring a simple
Java application on a local host with no security enforced, start it with
these options:

~~~~
java \
-Dcom.sun.management.jmxremote=true \
-Dcom.sun.management.jmxremote.port=12345 \
-Dcom.sun.management.jmxremote.authenticate=false \
-Dcom.sun.management.jmxremote.ssl=false \
-jar /usr/share/doc/openjdk-11-jre-headless/demo/jfc/Notepad/Notepad.jar
~~~~

In some situations (e.g. host with multiple network interfaces) it might be
necessary to set "-Djava.rmi.server.hostname={HOSTNAME}", where {HOSTNAME}
is the name of the host where application is running or its IP address.


This makes Java listen for incoming JMX connections on
port 12345 and tells it not to require authentication or SSL.

Note: "Notepad.jar" is proveded by "openjdk-11-demo" package.

Read more about JMX monitoring and management:

    http://docs.oracle.com/javase/1.5.0/docs/guide/management/agent.html
    http://docs.oracle.com/javase/6/docs/technotes/guides/jmx/
    https://docs.oracle.com/javase/9/management/monitoring-and-management-using-jmx-technology.htm
    https://support.oracle.com/knowledge/Middleware/1641501_1.html