Monitoring in Kubernetes
Since we now know how to examine our applications in Kubernetes, it's quite natural that we should have a mechanism to do so constantly to detect any incident at the first occurrence. To put it another way, we need a monitoring system. A monitoring system collects metrics from various sources, stores and analyzes data received, and then responds to exceptions. In a classical setup of application monitoring, we would gather metrics from, at the very least, three different layers of our infrastructure to ensure our service's availability as well as quality.
Application
The data we're concerned with at this level involves the internal states of an application, which can help us determine what's going on inside our service. For example, the following screenshot is from Elasticsearch Marvel (https://www.elastic.co/guide/en/marvel/current/introduction.html), called Monitoring from version 5 onward), which is a monitoring solution for an Elasticsearch cluster. It brings together...
