Consul as a monitoring service

There are two sides to monitoring: exposing problems and taking action to resolve them. Most monitoring systems handle the first, but Consul handles both. Seth Vargo explains how Consul enables self-healing infrastructure. By coupling service discovery with monitoring, Consul is able to intelligently route traffic away from unhealthy hosts or fail over to geographically different data centers.

There are two sides to monitoring: exposing problems and taking action to resolve them. Most monitoring systems handle the first, but Consul handles both. Consul is more than a traditional monitoring solution; it’s a runtime for the modern data center. Seth Vargo explains how Consul enables self-healing infrastructure by allowing infrastructure to adapt to the changing needs of any environment. Users can define any script for Consul to intelligently check and report the health status of all nodes in a cluster to expose problems. These scripts could be as simple as returning a 200 or as complex as querying the load and query response time on a database server. Other monitoring solutions already provide such functionality, but where Consul shines is in the second half of monitoring: automatic intervention to find solutions to problems without human operators. Since Consul has built-in health checking, it not only notifies operators of a node or service failure but also automatically routes traffic away from unhealthy nodes. Consul is also able to reroute traffic back to a troubled node once the node reports it is healthy again. In this way, Consul pushes the existing paradigms of monitoring, making it much more than a simple notification system. Rather it surfaces problems and solves them without human intervention.