[[heartbeat-overview]]
== Overview

Heartbeat is a lightweight daemon that you install on a remote server
to periodically check the status of your services and determine whether they are
available. Unlike {metricbeat}/index.html[Metricbeat], which only tells you if
your servers are up or down, Heartbeat tells you whether your services are
reachable.

Heartbeat is useful when you need to verify that you're meeting your service
level agreements for service uptime. It's also useful for other scenarios, such
as security use cases, when you need to verify that no one from the outside can
access services on your private enterprise server.

You can configure Heartbeat to ping all DNS-resolvable IP addresses for a
specified hostname. That way, you can check all services that are load-balanced
to see if they are available.

When you configure Heartbeat, you specify monitors that identify the
hostnames that you want to check. Each monitor runs based on the schedule that
you specify. For example, you can configure one monitor to run every 10
minutes, and a different monitor to run between the hours of 9:00 and 17:00.

Heartbeat currently supports monitors for checking hosts via:

* ICMP (v4 and v6) Echo Requests. Use the `icmp` monitor when you simply want to
check whether a service is available. This monitor requires root access. 
* TCP. Use the `tcp` monitor to connect via TCP. You can optionally configure this
monitor to verify the endpoint by sending and/or receiving a custom payload. 
* HTTP. Use the `http` monitor to connect via HTTP. You can optionally configure
this monitor to verify that the service returns the expected response, such as a
specific status code, response header, or content.

The `tcp` and `http` monitors both support SSL/TLS and some proxy settings. 
