Chapter 1. Introduction

Table of Contents

1.1. MonAMI architecture
1.2. The three monitoring flows
1.3. Datatrees

This document describes how to configure and run MonAMI: a universal sensor infrastructure. Following the Unix philosophy, it aims to do a simple job well. That job is to move monitoring information from a service into a monitoring system. It does not attempt to store monitoring information or display (graphically) the data, as other systems exist that already do this. Rather, it aims to interface well with existing software.

To understand how MonAMI may be configured, a brief introduction to the underlying ideas of MonAMI must be given. This introduction chapter will give an overview of how MonAMI allows monitoring information to flow. This is important as later chapters (which describe specific aspects of MonAMI) may be confusing without a clear understanding of the “big picture.

It is worth stressing at this stage that monitoring is a more involved process than merely periodically collecting data. Without a clear understanding of this, MonAMI may appear superfluous!

In essence, MonAMI allows the collection of information from one or more services. This information is then sent off, perhaps to some data storage or to be displayed within some monitoring software. This gathering of information can be triggered by MonAMI internally or from an external agent, depending on how MonAMI is configured.

1.1. MonAMI architecture

MonAMI has two parts: a core infrastructure and a set of plugins. Plugins do the more immediately useful activity, such as collecting information and sending the information somewhere. There are broadly two classes of plugins: monitoring plugins and reporting plugins.

Monitoring plugins can collect information from a specific source; for example, the MySQL plugin (described in Section 3.4.8, “MySQL”) can collect the current performance of a MySQL database. A configured monitoring plugin will act as a source of monitoring information.

Reporting plugins store gathered information or send it to some monitoring system. For example, the filelog plugin (described in Section 3.5.1, “filelog”) will store information as a single line within a log file, each line starting with the appropriate date/time stamp information. Another example is the Ganglia plugin (see Section 3.5.3, “Ganglia”), which sends network packets containing the information so that an existing Ganglia monitoring system can display the information. A configured reporting plugin will act as a sink of information.

A target is a configured instance of a plugin, one that is monitoring something specific or sending information to a specific information system. MonAMI can be configured so it has many MySQL targets, each monitoring target monitoring a different MySQL database server. Another example is when the filelog plugin is used to log data to different files. Although there is only ever one filelog plugin, there are many filelog targets, one per file.

MonAMI-core provides the infrastructure that allows gathered information (provided by monitoring plugins) to be sent to reporting plugins (which send the information off to where it is needed). MonAMI-core also handles internal bookkeeping and the functionality common between plugins, such as reading configuration files and caching results.

Diagram illustrating the MonAMI architecture.

Figure 1.1. Illustration of MonAMI architecture

Several useful plugins (both monitoring and reporting) are included with the default distribution. However, MonAMI aims to be extensible. Writing a new monitoring plugin allows data to be sent to any of the existing reporting plugins; writing a new reporting plugin allows any of the MonAMI data to be sent to a new storage or monitoring system. Instructions on how to write new plugins are given in the developers guide (the file README.developers).