[ZBXNEXT-701] Possibility to use subagents in zabbix-agent Created: 2011 Mar 14  Updated: 2014 Jan 06  Resolved: 2014 Jan 06

Status: Closed
Project: ZABBIX FEATURE REQUESTS
Component/s: Agent (G)
Affects Version/s: 1.8.4
Fix Version/s: None

Type: New Feature Request Priority: Major
Reporter: Marc Schoechlin Assignee: Unassigned
Resolution: Won't fix Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Duplicate
is duplicated by ZBXNEXT-1010 Co-processes for Agent for fast retri... Closed

 Description   

Hi,

thanks for writing this great piece of software.

Many companies run java software in their productive environments - currently it´s a little
bit difficult/uncomfortable to monitor the behavior of java-services with zabbix.
(see: http://www.kjkoster.org/zapcat/Zapcat_JMX_Zabbix_Bridge.html and
http://www.zabbix.com/documentation/1.8/manual/cookbook/specific?s[]=jmx#jmx)
A handy possibility to monitor java applications would be very welcome in many datacenters!

The java way to monitor applications is JMX (Java Management Extensions,
http://en.wikipedia.org/wiki/Java_Management_Extensions).

There are some specific solutions which use jmx-bridges deployed in application-servers - but existing possibilities
have some disadvantages:

  • it´s necessary to deploy the jmx-bridge in the application to be monitored
    (this is not not a good option - especially if you have support contracts for
    that applications)
  • it´s necessary to add a UserParameter for every monitored value to every agent
  • invoking a complete jvm for getting one single value consumes a lot of resources
    (especially if you monitor i.e. 20 items every minute)

In my opinion it would be a good idea to enhance the agent to have the possibility
to invoke a subagent and to communicate via stdin/stdout descriptors.
This can be used to write powerful tools which collect information in a flexible and
efficient way.

The configuration syntax could look like this:

SubAgent=java-jmx-agent-activemq,/usr/sbin/java --jmx-url "service:jmx:rmi:///jndi/rmi://localhost:9999/jmxrmi"
SubAgent=java-jmx-agent-generic,/usr/sbin/java --pidfile /var/run/jboss/jboss.pid

Agent and subagent may chat in the following way:

Gain list of measures
–
AGENT>list
SUBAGENT>foo
SUBAGENT>foobar
SUBAGENT>barfoo
–

Gain a measure
–
AGENT>get foobar
SUBAGENT>10111.5

AGENT>get barfoo
SUBAGENT>OK
–

Subagent child processes will be handeled like this:

  • they are started with the first monitoring request to the subagent item
  • they are stopped on agent shutdown with SIGTERM
  • they are restarted if subagent´s pid is missing

What do you think about this?

Do you have suggestion for the implementation?

Can you recommend some source locations?

Regards
Marc

 Comments   
Comment by Aleksandrs Saveljevs [ 2011 Mar 15 ]

Feature ZBXNEXT-555 (hopefully, soon to be merged into trunk) might solve your problem with JMX.

Comment by Marc Schoechlin [ 2011 Apr 18 ]

This might be cool.

Anyway - subagent support would be a great thing for enhancing the zabbix agent by complexer check-items.

Especially:

  • for reducing start overhead of checks
  • for checks which need to track and aggregate previous measurement values
Comment by Marc Schoechlin [ 2011 Apr 28 ]

Let me describe the "aggregate" thing a little bit more detailed:

We currently develop a commandline tool which collects statistics from a mysql database. Invoking a mysql connection for every ~300 different measurements is pretty resource consuming. To reduce the overhead of measurements my coworker created a small commandline utility (written in c) which collects all values with a single mysql-request and stores/caches them by using a shared memory segment.
The tool is invoked for every ~300 measurements, but uses shm-caching prevent DDOS of our mysql databases

We have to do this because there is currently no efficient way to transfer a high numbers of items/values to zabbix.

With the possibility of using a permanent process (managed by zabbix) this can be done very easy by any sysadmin with python/perl/python/ ...scripting-capabilities.
No need to write complex, performance-optimized and nifty tools.

Create a platform for exchanging and publishing tools/templates like this and call it "zabbix-exchange"

Comment by Marc Schoechlin [ 2011 Nov 23 ]

It would be a cool thing to use jmxterm as a subagent (http://wiki.cyclopsgroup.org/jmxterm)
Because establishing a jmx connection is expensive, a permanent connection via stdin/stdout to
a subagent would be beautiful/efficient....
--------------------------------------------
$ java -jar jmxterm-1.0-alpha-4-uber.jar -n
Welcome to JMX terminal. Type "help" for available commands.
jvms
5902 ( ) - jmxterm-1.0-alpha-4-uber.jar -n
open 5902
#Connection to 5902 is opened
domain java.lang
#domain is set to java.lang
bean type=Memory
#bean is set to java.lang:type=Memory
get *
#mbean = java.lang:type=Memory:
Verbose = false;

HeapMemoryUsage =

{ committed = 122421248; init = 127723648; max = 1817575424; used = 10287088; }

;

NonHeapMemoryUsage =

{ committed = 24313856; init = 24313856; max = 136314880; used = 11114696; }

;

ObjectPendingFinalizationCount = 0;
--------------------------------------------

Subagents will open a new world of agent-extensions....

Comment by richlv [ 2011 Nov 24 ]

hopefully jmx monitoring will be covered by the zabbix java gateway (http://www.zabbix.com/documentation/2.0/manual/config/items/itemtypes/jmx_monitoring)

Comment by Marc Schoechlin [ 2012 Jul 24 ]

Besides JMX, the subagent feature will also a cool thing to integrate complexer measurement tools with huge startuptimes of complex logic....

Comment by Marc Schoechlin [ 2014 Jan 06 ]

Possibly misunderstood, see ZBXNEXT-2098

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