# <a id="about-icinga2"></a> About Icinga 2

## <a id="what-is-icinga2"></a> What is Icinga 2?

Icinga 2 is an open source monitoring system which checks the availability of your
network resources, notifies users of outages, and generates performance data for reporting.

Scalable and extensible, Icinga 2 can monitor large, complex environments across
multiple locations.

## <a id="licensing"></a> Licensing

Icinga 2 and the Icinga 2 documentation are licensed under the terms of the GNU
General Public License Version 2, you will find a copy of this license in the
LICENSE file included in the source package.

## <a id="support"></a> Support

Support for Icinga 2 is available in a number of ways. Please have a look at
the support overview page at [https://support.icinga.org].

## <a id="contribute"></a> Contribute

There are many ways to contribute to Icinga - whether it be sending patches, testing,
reporting bugs, or reviewing and updating the documentation. Every contribution
is appreciated!

Please get in touch with the Icinga team at [https://www.icinga.org/ecosystem/].

## <a id="development"></a> Icinga 2 Development

You can follow Icinga 2's development closely by checking
out these resources:

* Development Bug Tracker: [https://dev.icinga.org/projects/i2?jump=issues] ([http://www.icinga.org/faq/how-to-report-a-bug/])
* Git Repositories: [https://git.icinga.org/?p=icinga2.git;a=summary] (mirror at [https://github.com/Icinga/icinga2])
* Git Checkins Mailinglist: [https://lists.icinga.org/mailman/listinfo/icinga-checkins]
* Development Mailinglist: [https://lists.icinga.org/mailman/listinfo/icinga-devel]
* \#icinga-devel on irc.freenode.net [http://webchat.freenode.net/?channels=icinga-devel] including a Git Commit Bot

For general support questions, please refer to [https://www.icinga.org/support/].

## <a id="demo-vm"></a> Demo VM

Icinga 2 is available as [Vagrant Demo VM](#vagrant).

## <a id="whats-new"></a> What's new

### What's New in Version 2.0.0 Beta 1

Lots of things. Please read [Icinga 2 in a nutshell](#icinga2-in-a-nutshell).

#### Changes

* Updated sample configuration for final release.

### Archive

Please check the `ChangeLog` file.

## <a id="icinga2-in-a-nutshell"></a> Icinga 2 in a Nutshell

* Use [Packages](#getting-started)

Look for available packages on [http://packages.icinga.org] or ask your distribution's maintainer.
Compiling from source is not recommended.

* Real Distributed Architecture

[Cluster](#distributed-monitoring-high-availability) model for distributed setups, load balancing
and High-Availability installations. Secured by SSL x509 certificates, supporting IPv4 and IPv6.

* High Performance

Multithreaded and scalable for small embedded systems as well as large scale environments.
Running checks every second is no longer a problem.

* Modular & flexible [features](#features)

Enable only the features you require. Want to use Icinga Web 2 with DB IDO but no status data?
No problem! Just enable ido-mysql and disable statusdata. Another example: Graphite should be enabled 
on a dedicated cluster node. Enable it over there and point it to the carbon cache socket.

* Native support for the [Livestatus protocol](#setting-up-livestatus)

In Icinga2, the 'Livestatus' protocol is available for use as either a UNIX, or TCP socket.

* Native support for [Graphite](#graphite-carbon-cache-writer)

Icinga 2 still supports writing performance data files for graphing addons, but also adds the
capability of writing performance data directly into a Graphite TCP socket simplifying realtime
monitoring graphs.

* Dynamic configuration language

Simple [apply](#using-apply) and [assign](#group-assign) rules for creating configuration object
relationships based on patterns. Supported with [duration literals](#duration-literals) for interval
attributes, [expression operators](#expression-operators), [function calls](#function-calls) for
pattern and regex matching and (global) [constants](#constants).
Sample configuration for common plugins is shipped with Icinga 2 as
part of the [Icinga Template Library](#itl).

* Revamped Commands

One command to rule them all - supporting optional and conditional [command arguments](#commands-arguments).
[Environment variables](#command-environment-variables) exported on-demand populated with
runtime evaluated macros.
Three types of commands used for different actions: checks, notifications and events.
Check timeout for commands instead of a global option. Commands also have custom attributes allowing
you to specify default values.

* Custom Runtime Macros

Access [custom attributes](#custom-attributes) with their short name, for example $mysql_user$,
or any object attribute, for example $host.notes$. Additional macros with runtime and statistic
information are available as well. Use these [runtime macros](#runtime-custom-attributes) in
the command line, environment variables and custom attribute assignments.

* Notifications simplified

Multiple [notifications](#notifications) for one host or service with existing users
and notification commands. No more duplicated contacts for different notification types.
Telling notification filters by state and type, even more fine-grained than Icinga 1.x.
[Escalation notifications](#notification-escalations) and [delayed notifications](#first-notification-delay)
are just notifications with an additional begin and/or end time attribute.

* Dependencies between Hosts and Services

Classic [dependencies](#dependencies) between host and parent hosts, and services and parent services work the
same way as "mixed" dependencies from a service to a parent host and vice versa. Host checks
depending on an upstream link port (as service) are not a problem anymore.
No more additional parents settings - host dependencies already define the host parent relationship
required for network reachability calculations.

* [Recurring Downtimes](#recurring-downtimes)

Forget using cronjobs to set up recurring downtime - you can configure them as Icinga2 configuration 
objects and specify their active time window.

* Embedded Health Checks

No more external statistic tool but an [instance](#itl-icinga) and [cluster](#itl-cluster) health
check providing direct statistics as performance data for your graphing addon, for example Graphite.

* Compatibility with Icinga 1.x

All known interfaces are optional available: [status files](#status-data), [logs](#compat-logging),
[DB IDO](#configuring-ido) MySQL/PostgreSQL, [performance data](#performance-data),
[external command pipe](#external-commands) and for migration reasons a
[checkresult file reader](#check-result-files) too.
All [Monitoring Plugins](#setting-up-check-plugins) can be integrated into Icinga 2 with
newly created check command configuration if not already provided.
[Configuration migration](#configuration-migration) is possible through the Icinga Web 2 CLI tool.
Additional information on the differences is documented in the [migration](#differences-1x-2) chapter.

* [Vagrant Demo VM](#vagrant)

Used for demo cases and development tests. Get Icinga 2 running within minutes and spread the #monitoringlove
to your friends and colleagues.