Cacti 0.8 Beginner's Guide: Learn Cacti and design a robust Network Operations Center

As most of Cacti is built as a web interface, a web server is needed. This can be Apache's httpd or Microsoft's Internet Information Server (IIS) if installing on Windows, but in fact, any PHP-capable web server can be used to run the web interface. For optimal support, the use of Apache or IIS is suggested.

Cacti is built with the PHP programming language and therefore needs PHP to be installed on the system. Most Linux distributions already have a base PHP environment installed, but some might need additional packages for Cacti to function properly. In particular, the LDAP, SNMP, and MySQL extensions should be installed.

Cacti uses the freely available MySQL database engine as its database server and it is available on most operating systems. One should note that the database server does not need to be installed on the same host as Cacti. For best performance, MySQL version 5 should be used.

The NET-SNMP package provides the SNMP binaries used by Cacti and supports SNMPv1, SNMPv2c, and SNMPv3.

The NET-SNMP package also provides the SNMP daemon for Linux.

Assume that the CentOS system has been installed with only the "Server Package" selected and there is no graphical user interface installed.

This is the default installation for a CentOS system with no manual package selection.

You just gave the system a location to find the remaining packages needed for the Cacti installation and then installed them; therefore, you are now ready to start the next installation phase.

Go to http://www.cacti.net and download the latest version of Cacti. In the top-left corner, under Latest Files, right-click on the tar.gz file and save the link address to the clipboard. You are going to need this link later. For simplicity we're assuming that your server has an Internet connection.

You downloaded the latest Cacti version to the root directory of the web server and created a symbolic link to the extracted directory. With the Cacti files in place, you are now ready for the next phase of the installation process.

The database isn't automatically created during the installation of Cacti. Therefore, you need to create it here. At the same time, a database user for Cacti should be created to allow it to access the database. It's also a good idea to secure the MySQL database server by using one of the included CentOS tools.

You used some tools to secure the MySQL server and created a database. You also filled the Cacti database with the initial data and created a MySQL user for Cacti. However, Cacti still needs to know how to access the database, so let's move on to the next step.

In case you are not using CentOS to install Cacti, you can use some MySQL internal functions to secure your installation.

You need to tell Cacti where to find the database and which credentials it should use to access it. This is done by editing the config.php file in the include directory.

You changed the database configuration for Cacti to the username and password that you created earlier. These settings will tell Cacti where to find the database and what credentials it needs to use to connect to it. You also changed the default URL path to fit your installation. As you install Cacti to /var/www/html/cacti, a sub-directory of the document root, you need to change this setting to /cacti/, otherwise Cacti will not work correctly.

For the poller to work correctly, Cacti needs a system user account. You are going to create one now and also set up the poller's cron entry.

You just created a system user which runs the Cacti poller and scheduled the poller to run every 5 minutes. Five minutes is the default interval, but it can be changed to 1 minute if needed. For more information on how to do so, go the following post in the Cacti forums: http://forums.cacti.net/viewtopic.php?p=116403.

By default, Cacti comes with a poller written in PHP. For small-to-medium installations, this poller does its job just fine, but for larger installations, an alternative poller, spine, needs to be used. It is written in C and is much faster than the original poller, as it makes use of the multi-tasking capabilities of modern operating systems and hardware.

Here we will deep-dive into installing and configuring the spine poller.

You just set up a basic development environment for compiling Spine, compiled it, and then installed it. You also configured Spine to use the correct database information.

The main difference between installing Cacti from source and using APT/Yum-based installations is the location of configuration files and availability of patches. Cacti, by default, does not follow the Filesystem Hierarchy Standard (FHS) defined for the Linux operating systems. The FHS defines directories where applications should add their configuration or log files. APT/Yum-based installations usually follow this standard. Due to this, add-ons such as the Plugin Architecture may not be available on all platforms using APT/Yum.

The main advantage of using APT/Yum-based installations is the ease of installation but as we've just seen, installing Cacti isn't very difficult.

However, the disadvantage of using APT or Yum is the availability of newer Cacti versions. Source-based Cacti installations can be upgraded to the latest version as soon as it is available on the Cacti website, while APT/Yum-based installations might need to wait until the package maintainers update their repositories.

Here is a little challenge for you. It's not difficult but it will allow you to alter the installation to suit your needs. What if you want to use a remote database server? Maybe you want to use an existing dedicated MySQL server, instead of hosting the database on the same system as Cacti, or you want to separate the roles to allow more growth. Can you figure out what to change?

Solution: Create the MySQL database on the remote system using the same command as if you were installing it locally, but this time use the -h <hostname> option to specify the remote server. When creating the user and granting it permissions, use the following command, assuming the Cacti server has the IP '192.168.0.10':

GRANT ALL ON cacti.* TO cactiuser@'192.168.0.10' IDENTIFIED BY 'MyV3ryStr0ngPassword'; 
flush privileges; 
exit

This will allow the Cacti user access to the database from the Cacti server. Now change $database_hostname in config.php and DB_Host in spine.conf on the Cacti server to point to your remote database server.

Instead of installing every prerequisite individually, the community-built Windows Installer provides a convenient way of installing them together with Cacti.

You installed Cacti on Windows along with all the prerequisites.

Unlike Linux, where compilation from source is the preferred method, Cacti has pre-compiled binaries for Windows. You can download the latest versions from http://www.cacti.net. Click on Download under the Spine (Cactid) section and download the latest Windows binary from there. Extract the archive to the computer running Cacti and edit spine.conf to fit your database settings. In case you want to compile spine yourself, you will have to install a working copy of Cygwin. The following URL will provide you with some information on how to compile Spine using Cygwin:

http://www.cacti.net/spine_install_wincyg.php.

You upgraded Cacti to a newer version. As a safety net, you created a backup of the database so you can revert back to the old version in case of an error. You copied the RRD files and other resources to the new installation and switched over by changing the symbolic link to point to the new location. You finished the upgrade process by going to the install URL which provided the final web-based upgrade process.

You finalized your Cacti installation by running the included web-based installer. If you have been following the instructions correctly, you will now have a working Cacti installation.

The installation will leave you with the default cmd.php poller. If you want to use Spine, you will now have to logon to the Cacti web interface and set the Spine Poller File Path in the Paths section of the Settings page. You also have to change the Poller Type to Spine in the Poller section.

The Console tab is where you manage your Cacti installation. From here you can add devices and users or create graphs and assign them to a tree. We're going to explain each of the menu sections next.

The Graphs tab is the main screen for end users. Here they can view the graphs for their devices and systems and also change some personal settings:

The Graphs tab contains a hierarchical tree to the left containing all of the devices which a user is allowed to view. The main part of the page contains the graphs and a filtering system which can be used to customize the timeframe or to search for specific graphs.