You can see the sample code for this post on Github.

Consul Watches offer a way to hook into changes to the Consul cluster state at runtime.The specific type of changes we will be looking at hooking into in this post are checks. Whenever a node or service comes online and registers to Consul, whenever an existing node or service leaves Consul, or whenever an existing node or service becomes unresponsive, Consul will emit a check event. This check event can invoke a process to monitor the health of our services, alerting human being that action might soon be necessary.

In a previous post, we saw how to provision a simple consul client/server cluster using Ansible. We will now look at interacting with that cluster by showing how to register a spring boot application to it, using spring cloud consul.

The source code for this blog post can be found on GitHub.

Consul can run in either client or server mode. As far as Consul is concerned, the primary difference between client and server mode are that Consul Servers participate in the consensus quorum, store cluster state, and handle queries. Consul Agents are often deployed to act as middle-men between the services and the Consul Servers, which need to be highly available by design.

You can find the source code for this post on GitHub.

Consul is a distributed service discovery engine. It’s primary purpose is to track and manage services that interact with it–usually via an HTTP API. It monitors the health of services in near real time, providing a more robust way of routing services to healthy and responsive nodes.