What is Sensu?

Sensu is an infrastructure and application monitoring and telemetry solution. Sensu provides a framework for monitoring infrastructure, service & application health, and business KPIs. Sensu is specifically designed to solve monitoring challenges introduced by modern infrastructure platforms with a mix of static, dynamic, and ephemeral infrastructure at scale (i.e. public, private, and hybrid clouds).

Sensu allows organizations to compose comprehensive monitoring & telemetry solutions to meet unique business requirements. By providing a platform to build upon, Sensu enables you to focus on what to monitor and measure, rather than how. Sensu is installed on your organizations infrastructure – it is not a Software-as-a-Service (SaaS) solution – which means Sensu gives you full control over the availability of your monitoring solution.


Sensu is a comprehensive infrastructure and application monitoring solution that provides the following benefits:

  • Monitor servers, services, application health, and business KPIs

Sensu is an infrastructure and application monitoring & telemetry solution.

  • Send alerts and notifications

Sensu integrates with the tools and services your organization is already using to do things like send emails, PagerDuty alerts, Slack, HipChat, IRC notifications, and many more.

  • Dynamic client registration & de-registration

When servers are provisioned, they automatically register themselves with Sensu, so there’s no need to manually add or configure new servers.

  • A simple yet extensible model for monitoring

Sensu provides a sophisticated, yet simple to understand solution for executing service checks and processing events at scale. Service checks provide status and telemetry data, and event handlers process results. Hundreds of plugins are available for monitoring the tools and services you’re already using. Plugins have a very simple specification, and can be written in any programming language.

  • Built for mission-critical applications and multi-tiered networks

Sensu’s use of a secure transport protects your infrastructure from exposure and makes it possible for Sensu to traverse complex network topologies, including those that use NAT and VPNs, and span public networks. Sensu provides a secure monitoring solution trusted by international banking institutions, government agencies, Fortune 100 organizations, and many more.

  • Designed for automation

Sensu exposes 100% of its configuration as JSON files, which makes it extremely automation–friendly (e.g. it was designed to work with tools like Chef, Puppet, and Ansible).

  • Open source software with commercial support

Sensu is an open-source software (OSS) project, made freely available under a permissive MIT License (the source code is publicly available on GitHub). Sensu Enterprise is based on Sensu Core (the OSS version of Sensu) which makes added-value features, commercial support, training, and many other benefits available under the Sensu License.

A Simple, Yet Powerful Framework

Sensu is a comprehensive monitoring solution that is powerful enough to solve complex monitoring problems at scale, yet simple enough to use for traditional monitoring scenarios and small environments. It achieves this broad appeal via building upon two simple, yet powerful monitoring primitives: Service Checks and Event Processing. These building blocks also provide an infinitely extensible framework for composing monitoring solutions.

What is a Service Check?

Service checks allow you to monitor services (e.g. is Nginx running?) or measure resources (e.g. how much disk space do I have left?). Service checks are executed on machines running a monitoring agent (i.e. Sensu client). Service checks are essentially commands (or scripts) that output data to STDOUT or STDERR and produce an exit status code to indicate a state. Common exit status codes used are 0 for OK, 1 for WARNING, 2 for CRITICAL, and 3 or greater to indicate UNKNOWN or CUSTOM. Sensu checks use the same specification as Nagios, therefore, Nagios check plugins may be used with Sensu. Service checks produce results that are processed by the event processor (i.e. the Sensu server).

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What is Event Processing?

Event processing (also called stream processing) is a method of analyzing (processing) and storing streams of information (data) about things that happen (events), deriving a conclusion from them, and potentially executing some action (handling). The Sensu event processor (the Sensu server) enables you to execute Handlers for taking action on events (produced by service checks), such as sending an email alert, creating or resolving an incident (e.g. in PagerDuty or ServiceNow), or storing metric data in a time-series database (e.g. Graphite).

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How Sensu Works