If this than that recipes alert for Commuter Train trouble

The ingredient is tweet, Twitter Search use case is no longer just sentiment analysis, its function extends to alert, even close to real time–I’m pretty optimistic given the number of Commuter Line users joining the conversation. Now, the no-code part of our recipe, a Twitter search query, that is

(to:krlmania OR @krlmania OR from:CommuterLine)
AND (gangguan OR pantograf OR wesel OR patah)
-semoga -smoga -moga

and a brief explanation is that it queries for some keywords for potential trouble within mentions/replies to @krlmania and official announcements of @CommuterLine. Exclusion added to the search, the sentiment part of tweets, expressing wishes to shoo trouble away–I’m sorry, but keep praying online anyway.

When Twitter launched Twitter Stories in 2011, I read about Ravi Pina running the crowd sourced @Caltrain. Later now I see that official accounts like @SMRT_Singapore is also a model of service disruption info center. We can go deeper to better stats from the API web service that shows real time position (an app is out there showing that the location data API is working), but until its open data status is known, crowd sourcing stays as the most reliable solution, independent to regulation, and easiest to implement. Does the recipe work? During the first week of testing, alerts were flooding–within limit of course–as trouble really happened. So, cook your own ingredients or get my recipes served here.

Both of course based on .htaccess manipulation (mod_rewrite of Apache must be enabled). I install Yourls in side http://my.web/somedir. To make my short URL to use something like http://my.web/xGf12 instead of http://my.web/somedir/xGf12, I run the regular install with that somedir as based URL, but then create .htaccess in http://my.web/.htaccess (instead of http://my.web/somedir/.htaccess) However, I intend to use prefix x for the shorten URL. Here is how the regular expression implemented:

# BEGIN YOURLS
 
RewriteEngine On
RewriteBase /somedir/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(x[0-9A-Za-z]+)/?$ /somedir/yourls-go.php?id=$1 [L]
RewriteRule ^(x[0-9A-Za-z]+)\+/?$ /somedir/yourls-infos.php?id=$1 [L]
RewriteRule ^(x[0-9A-Za-z]+)\+all/?$ /somedir/yourls-infos.php?id=$1&all=1 [L]
 
# END YOURLS

I decided to install in RedHat 5.2. Maybe it is easier in Ubuntu (Nagios 3 already listed in the repository, but I haven’t tried it). As pointed out by the quickstart (it is meant for Fedora by the way), requirements are:

1. php, httpd
2. gcc, glibc, glibc-common
3. gd, gd-devel

After getting those, the configure-make-install procedure runs well, except that I don’t check the warnings. It turns out that only some of Nagios core components are installed. It can be seen from the content of /usr/local/nagios/libexec directory. There is no check_snmp etc. Error also appears in statusmap page of Nagios.

Compile More Nagios Core Components

I run through ./configure once more, check out all warnings, and begin to evaluate requirements (found this text inside nagios-plugins-1.4.14 tarball)

MySQL

For check_mysql functionality, mysql (MySQL client for linux) must be installed. ./configure also test this client, by default config, to the local MySQL socket, hence mysql-server must also exist.

Radius Client

Client from freeradius package doesn’t meet Nagios requirements. It must be the ones from original radiusclient, I found RPMs for radiusclient-0.3.2-0.2.el5.rf.i386.rpm and radiusclient-devel-0.3.2-0.2.el5.rf.i386.rpm.

GD

It is quite tricky to get statusmap.c to be compiled for the .cgi of Nagios status map. Compilation needs gd library from http://www.libgd.org/. gd requires zlib, libjpeg, and libpng. On first attempt, I installed from RPMs. This appeared to be not working as I could still see warnings about gd2 during ./configure.

So, I choose to compile from the source gd-2.0.33.tar.bz2. This tarball was found in the older section of current gd2 web. I chose this version because the RPM used was gd-2.0.33-9.4.el5_1.1.rpm. I removed this RPM first which made me to remove also libmwf and ImageMagick.

After straightforward  configure-make-install the library will be installed under /usr/local/lib i.e libgd.so.2.0.0. Header files will also be available in /usr/local/include i.e gd.h. These are different from the situation when I installed from RPM where libgd.so.2.0.0 is under /usr/lib/ and no gd.h found under /usr/include.

So, I make devclean and rerun

./configure --with-gd-lib=/usr/local/lib --with-gd-inc=/usr/local/include --with-command-group=nagcmd

I configure the /usr/local/nagios/etc/cgi.conf but status map page is still empty. Next workaround is to install back  gd-2.0.33-9.4.el5_1.1.rpm. (which also bring back libmwf and ImageMagick) and point the gd library to the ones created from RPM. I make devclean and rerun:

./configure --with-gd-lib=/usr/lib --with-gd-inc=/usr/local/include --with-command-group=nagcmd

At this point I regret not to have Ubuntu implementation in the first place. Just a small regret.

Other library needed for check_smtp, check_http, etc. don’t seem to trouble me much, I need openssl, openldap, etc. and simply get them from RPMs.

In localhost snmpd is installed and configured /etc/default/snmpd:

SNMPDOPTS='-Lsd -Lf /dev/null -u snmp -I -smux -p /var/run/snmpd.pid'

and edit /etc/snmp/snmpd.conf to have:

com2sec readonly  localhost         <some community string>

Install snmp, then I can test snmpwalk:

$ snmpwalk -Os -c <some community string> -v 1 localhost system

Cacti requires RRDTool and the correct version to be set in Settings menu of the Cacti web console. In my case, RRDTool version is 1.3x. In Cacti 0.8.6.x and above poller.php is called by cron instead of cmd.php, put this trough crontab in Cacti user (enter this Cacti user crontab from crontab -e -u or embed the user in crontab by root instead of individually edited).

*/2 * * * * /usr/bin/php /var/www/cacti/poller.php

It will generate file under rra directory of the web /var/www/cacti/rra/.rrd. RRD tool will create image based on this polling result file.