Health checks

Kubernetes provides three layers of health checking. First, in the form of HTTP or TCP checks, K8s can attempt to connect to a particular endpoint and give a status of healthy on a successful connection. Second, application-specific health checks can be performed using command-line scripts. We can also use the execcontainer to run a health check from within your container. Anything that exits with a 0 status will be considered healthy.

Let's take a look at a few health checks in action. First, we'll create a new controller named nodejs-health-controller.yaml with a health check:

apiVersion: v1 
kind: ReplicationController 
metadata: 
  name: node-js 
  labels: 
    name: node-js 
spec: 
  replicas: 3 
  selector: 
    name: node-js 
  template: 
    metadata: 
      labels: 
        name: node-js 
    spec: 
      containers: 
      - name: node-js 
        image: jonbaier/node-express-info:latest 
        ports: 
        - containerPort: 80 
        livenessProbe: 
        ...