zabby Documentation Release Evgeniy Petrov

Transcription

1 zabby Documentation Release Evgeniy Petrov November 02, 2013

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3 CONTENTS 1 Introduction Goals Maturity How zabby works Requirements Python Operating system Installation From source From debian package Testing your installation Extending tutorial Monitoring a constant Monitoring content of a file Monitoring result of executing commands in a shell i

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5 CHAPTER ONE INTRODUCTION 1.1 Goals Be easy to understand Be easy to modify Be easy to extend and maintain extensions 1.2 Maturity Zabby is used on all production Linux servers at i-free since august 2013, this includes debian lenny(we are building required python 2.6 packages), squeeze and wheezy. There are plans to use zabby to monitor windows servers. 1.3 How zabby works Zabby s only function is to answer requests of the following form(zabbix format) key[argument1,argument2] Answers are calculated by looking up 1 functions by key and calling them with provided arguments, like so(python call) functions[key](argument1, argument2) Result of this call will be sent as a response. If anything unexpected happens(there is no function associated with key, wrong arguments are provided for function, function throws exception) ZBX_NOTSUPPORTED will be sent as a response. 1 Key/function associations are obtained from python files. If there are several functions with the same key, zabby will use function that was loaded last. 1

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7 CHAPTER TWO REQUIREMENTS 2.1 Python Zabby supports Python >=2.6 and >= Operating system Currently zabby only supports Linux(>=2.6.26), but there are plans to support other operating systems. 3

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9 CHAPTER THREE INSTALLATION 3.1 From source You can clone the public repo: $ git clone Or download tarball. Once you have the source, you can install it into your site-packages with $ python setup.py install After installing zabby run it with $ zabby -c /usr/local/lib/python2.6/dist-packages/zabby/examples/config.py Config path will differ, based on your python version 3.2 From debian package Install build dependencies $ aptitude install devscripts build-essential Build $ debuild Install $ dpkg -i../zabby*.deb Zabby will be started automatically by post-install script. 3.3 Testing your installation After installing and running zabby query it with $ zabby_get agent.ping 5

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11 CHAPTER FOUR EXTENDING TUTORIAL 4.1 Monitoring a constant To monitor anything with zabby you must write a function and associate it with a key. Create a file named 30_constants.py with the following content def one(): return 1 items = { one : one, } And place it in items directory of your zabby configuration directory(default in debian packages is /etc/zabby/items). Start or reload zabby, you should see something like this in the log :44:03 DEBUG [zabby.config_manager] Loading items from /etc/zabby/items/30_constants.py Now you can query zabby for your constant $ zabby_get one 1 You ve created an extension file for zabby, you ve defined a function that always returns 1 and you have associated it with a key one. Now every time zabby receives a request with key one it will call this function and answer with the result of calling this function. 4.2 Monitoring content of a file Say you want to monitor when was the last time that puppet client ran successfully on a server. You can make puppet do something like this 1, after every successful run /bin/date +%s > /tmp/puppet_last_run~; mv /tmp/puppet_last_run~ /tmp/puppet_last_run The only thing needed now is to read the value from a file. Create a file named 30_puppet.py with the following content 1 mv is an atomic operation on POSIX systems, while opening, writing to a file, flushing and closing it is not an atomic operation. Using /bin/date +%s > /tmp/puppet_last_run may cause occasional reads of an empty file 7

12 zabby Documentation, Release from zabby.core.utils import lines_from_file def puppet_last_run(): Returns the epoch describing the last time puppet has succesfully ran. /tmp/puppet_last_run is filled by puppet client with output from date +%s lines = lines_from_file( /tmp/puppet_last_run ) last_run = lines[0] return last_run items = { puppet.last_run : puppet_last_run, } Zabby contains some useful function that can be used in extensions. lines_from_file reads all lines from a file and presents them as a list. Run a python interpreter supplying it with created file and call the function you have just defined $ sudo -u zabby python -i 30_puppet.py >>> puppet_last_run() Traceback (most recent call last):... IOError: [Errno 2] No such file or directory: /tmp/puppet_last_run If that function went into production you would receive ZBX_NOTSUPPORTED if /tmp/puppet_last_run was missing on any of your servers. But absence of this file probably means that puppet never ran, and we would like to detect such situations. Edit 30_puppet.py so that puppet_last_run looks like this def puppet_last_run(): try: lines = lines_from_file( /tmp/puppet_last_run ) last_run = lines[0] except IOError: last_run = 0 return last_run This way, if file is missing, it is assumed that puppet never ran and 0 is returned to indicate just that. Run python interpreter again $ sudo -u zabby python -i 30_puppet.py >>> puppet_last_run() 0 $ date +%s > /tmp/puppet_last_run $ sudo -u zabby python -i 30_puppet.py >>> puppet_last_run() Now, if you create a trigger like puppet_last_run < (now() - 1h) it will generate an event even if /tmp/puppet_last_run is missing. 8 Chapter 4. Extending tutorial

13 zabby Documentation, Release Monitoring result of executing commands in a shell Sometimes it is not practical to write a function in pure python, especially if you already have a working combination of executable files. Say you need to monitor a number of zombie processes. Create a file named 30_zombie_processes.py with the following content from zabby.core.utils import sh items = { "zombie_processes.count": sh("ps -A -o state,pid grep Z wc -l"), } sh returns a function that, when called, executes given command in a shell and returns everything this command has written to standard output. Run python interpreter >>> items[ zombie_processes.count ] <function call_command at 0x7fcb0bdfad70> >>> items[ ifree.zombie_process.count ]() 0 The function returned by sh is now associated with a key Monitoring result of executing commands in a shell 9