If the application malfunctions, the pod and container may still be running but the application may no longer be running. This is where health checks come in.

The typical prod application behind a load balancer should always have health checks implemented in some way to ensure availability and resiliency.

Below you can see where the healthcheck is. You can check the port or container port name.

# pod-helloworld.yml
apiVersion: v1
kind: Pod
metadata:
  name: nodehelloworld.example.com
  labels:
  app: helloworld
spec:
  # The containers are listed here
  containers:
    - name: k8s-demo
      image: okeeffed/docker-demo
      ports:
        - containerPort: 3000
      # ! This is the health check
      livenessProbe:
        httpGet:
          path: /
          port: 3000
        initialDelaySeconds: 15
        timeoutSeconds: 30
copy

More explicit information can be found here.