Purpose

You are monitoring one or several computers running Mac OS X on your local network using cacti — but the Memory Usage graph is empty? No wonder: Apple does not provide /proc/meminfo where net-snmp usually would derive this information from.

In order to remedy this situation, I borrowed two scripts available online, modified and integrated them into my setup.

Using the memory.py script and some tweaks to /etc/snmp/snmpd.conf, I can insert information from running vm_stat on the local computer (ie. the computer to be monitored by cacti) into SNMP.

Using check_snmp_extend.py - or actually rather the wrapper script mac_memory.sh - I can query the SNMP servers on my Macs for the memory attributes provided by memory.py and pass this information to cacti.

Installation Instructions

On the Mac you want to monitor using SNMP

1. Copy memory.py to a convenient location on your Mac, e.g. /usr/local/bin
2. Make memory.py readable and executable for the SNMP user
3. Add all lines starting with exec in snmpd.partial.conf to /etc/snmp/snmpd.conf

• Adjust path to memory.py according to the location of the script defined in first step

1. Restart snmpd daemon using restart-snmp.sh

If you want to check whether SNMP returns memory information, execute the following command on the Mac you want to monitor:

snmpwalk -v 1 -c public localhost .1.3.6.1.4.1.2021.8.1
UCD-SNMP-MIB::extIndex.1 = INTEGER: 1
UCD-SNMP-MIB::extIndex.2 = INTEGER: 2
UCD-SNMP-MIB::extIndex.3 = INTEGER: 3
UCD-SNMP-MIB::extIndex.4 = INTEGER: 4
UCD-SNMP-MIB::extIndex.5 = INTEGER: 5
UCD-SNMP-MIB::extNames.1 = STRING: memory_free
UCD-SNMP-MIB::extNames.2 = STRING: memory_wired
UCD-SNMP-MIB::extNames.3 = STRING: memory_active
UCD-SNMP-MIB::extNames.4 = STRING: memory_inactive
UCD-SNMP-MIB::extNames.5 = STRING: memory_used
UCD-SNMP-MIB::extCommand.1 = STRING: /usr/bin/python
UCD-SNMP-MIB::extCommand.2 = STRING: /usr/bin/python
UCD-SNMP-MIB::extCommand.3 = STRING: /usr/bin/python
UCD-SNMP-MIB::extCommand.4 = STRING: /usr/bin/python
UCD-SNMP-MIB::extCommand.5 = STRING: /usr/bin/python
UCD-SNMP-MIB::extResult.1 = INTEGER: 0
UCD-SNMP-MIB::extResult.2 = INTEGER: 0
UCD-SNMP-MIB::extResult.3 = INTEGER: 0
UCD-SNMP-MIB::extResult.4 = INTEGER: 0
UCD-SNMP-MIB::extResult.5 = INTEGER: 0
UCD-SNMP-MIB::extOutput.1 = STRING: 7727325184
UCD-SNMP-MIB::extOutput.2 = STRING: 2521927680
UCD-SNMP-MIB::extOutput.3 = STRING: 2995613696
UCD-SNMP-MIB::extOutput.4 = STRING: 2286985216
UCD-SNMP-MIB::extOutput.5 = STRING: 7804522496
UCD-SNMP-MIB::extErrFix.1 = INTEGER: noError(0)
UCD-SNMP-MIB::extErrFix.2 = INTEGER: noError(0)
UCD-SNMP-MIB::extErrFix.3 = INTEGER: noError(0)
UCD-SNMP-MIB::extErrFix.4 = INTEGER: noError(0)
UCD-SNMP-MIB::extErrFix.5 = INTEGER: noError(0)
UCD-SNMP-MIB::extErrFixCmd.1 = STRING: 
UCD-SNMP-MIB::extErrFixCmd.2 = STRING: 
UCD-SNMP-MIB::extErrFixCmd.3 = STRING: 
UCD-SNMP-MIB::extErrFixCmd.4 = STRING: 
UCD-SNMP-MIB::extErrFixCmd.5 = STRING:

On the cacti server

1. Copy mac_memory.sh and check_snmp_extend.py to <cacti>/scripts

In the cacti web interface

1. Log into the administration interface
2. In the console tab, select "Import Templates" in the section "Import/Export"
3. Import cacti_graph_template_mac_os_x_-_memory_usage_-_graph_template.xml
4. Add the graph template Mac OS X - Memory Usage - Graph Template to an existing device
5. Enjoy!

Links

• http://apple.stackexchange.com/questions/4286/is-there-a-mac-os-x-terminal-version-of-the-free-command-in-linux-systems
• http://www.cmdln.org/2011/04/28/extended-monitoring-via-snmp/