Am new to cacti so please forgive me if my question sounds stupid, I have tried my best to find the solution for the problem but still needs help. I want to gather number of lines in the haproxy.log file from a remote front end(FE) machine, I have added this device successfully in cacti and graphs like load average are being drawn. I followed this: http://www.cacti.net/downloads/docs/html/how_to.html to add a graph to this device using shell script, I added a Data input method selecting Script/Command as the input type and /home/ubuntu/script.sh as the input string, added a output field too. Next I added a data source with out a template and selecting FE as the host, then as mentioned in the link I added the graph and things look fine till now, problem is that nothing is being plotted in the graph, cacti log files(Debug mode) shows the following:

CMDPHP: Poller[0] Host[5] DS[29] CMD: /home/ubuntu/script.sh, output: U 12/30/2011 12:35:07 AM - CMDPHP: Poller[0] Host[5] DS[29] WARNING: Result from CMD not valid. Partial Result: U

Now I know that script should print out the output only as this is one output field, my script contains the following

temp=$(sudo ssh -i /home/ubuntu/key.pem user@ '/var/log/haproxy.log | wc -l') echo $temp

the script is owned by ubuntu as there is no cacti user on cacti server, someone else installed cacti server and I have now been asked to take care of it.

If I execute the script from cacti server command line it works fine and am executing it as user ubuntu only.

Please help me I dont know where am I going wrong.



From memory, the cacti poller runs as the www-data user, therefore won't have permission to read your private key.

  • Thanks for the reply, so can you please suggest how can I connect to the remote machine to get the data. – APZ Dec 30 '11 at 15:09
  • First thing, check it actually is www-data the poller's running as. There should be a job in /etc/cron.d somewhere that fires it every 5 minutes. Then chown the private key file to www-data. Finally su to the www-data user: su - www-data and try to run the script from as the www-data user and see if it works. – growse Dec 30 '11 at 15:19
  • but isn't changing the ownership of pem key to www-data insecure? – APZ Dec 30 '11 at 15:38
  • Quite probably. Which is why SNMP might be a better way to go, rather than logging in via SSH just to count the number of lines in a text file. snmpd on ubuntu can handle the exec statement to run a script in response to a particular SNMP query, and cacti loves using SNMP for everything. In fact, I'll write you a better answer. – growse Dec 30 '11 at 15:43

SSH isn't a brilliant way for cacti to get data from remote machines. There's numerous alternatives, but the one I've had success with is using SNMP to return data from the remote host back to cacti.

The SNMP daemon on ubuntu can use the exec configuration to execute scripts in response to specific SNMP queries. The example given in the ubuntu snmpd.conf is this:

exec . mailq /usr/bin/mailq

This will return the current mailq output to any client that queries . You should be able to set up something similar and configure cacti to use a simple SNMP query to receive the data.

This is a lot easier than faffing around with custom script inputs, in my view.

  • I tried what u mentioned, added sh shelltest /bin/bash /tmp/shtest to conf file but the output am getting is not correct. UCD-SNMP-MIB::extIndex.1 = INTEGER: 1 UCD-SNMP-MIB::extCommand.1 =STRING: /bin/bash UCD-SNMP-MIB::extResult.1 = INTEGER: 0 UCD-SNMP-MIB::extOutput.1 = STRING: 0 UCD-SNMP-MIB::extErrFix.1 = INTEGER: noError(0) UCD-SNMP-MIB::extErrFixCmd.1 = STRING: Please help me in getting just the lines in haproxy log file getting displayed, script is owned by ubuntu. Please help. – APZ Jan 2 '12 at 2:12
  • Continuation of the last comment, I used snmp walk command and got this output both on local machine and from cacti server. – APZ Jan 2 '12 at 2:23
  • That snmp output says that you just ran bash, and it exited code 0. Why are you trying to run sh shelltest /bin/bash /tmp/shtest? Why not just have exec [oid] shelltest /tmp/shtest directly? What happens if you run shtest from the command line? Also, don't put scripts like this in /tmp - There's no guarantee that they'll get left alone by the kernel. Put them in /usr/local/bin/ or similar instead. – growse Jan 2 '12 at 10:45
  • from the command line, shtest gives the right output:25061(number of lines in haproxy.log file) but when I use snmpwalk snmpwalk -v 1 -c aaaa . I get permission denied UCD-SNMP-MIB::extIndex.1 = INTEGER: 1 UCD-SNMP-MIB::extNames.1 = STRING: shelltest UCD-SNMP-MIB::extCommand.1 = STRING: /bin/bash UCD-SNMP-MIB::extResult.1 = INTEGER: 0 UCD-SNMP-MIB::extOutput.1 = STRING: cat: /var/log/haproxy.log: Permission denied UCD-SNMP-MIB::extErrFix.1 = INTEGER: noError(0) UCD-SNMP-MIB::extErrFixCmd.1 = STRING: – APZ Jan 3 '12 at 18:44
  • Sounds like the user snmpd is running as doesn't have permission to read haproxy.log. – growse Jan 3 '12 at 19:08

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