title: How Kubernetes HPA works?
body: <p>I am trying to add Horizontal Pod Autoscaling (HPA) to my Kubernetes Deployments. My application is composed by 5 microservices which are connected between them. I have one NodePort (a Traefik service) which is in charge of controlling the traffic from the outside.
  The call is a HTTPS POST that sends a csv file which is processed by the application. It can be send via command line or using a web app (UI). The curl command will be like:</p>
  
  <pre><code>curl https://our_app_name -X POST -F "file=@test.csv"
  </code></pre>
  
  <p>The questions I have about the functionality of HPA are the following,</p>
  
  <ol>
  <li><p>How HPA distributes the calls between the replicas? Is Kubernetes capable of parallel computing, i.e., divide the call between the replicas or each call goes to only one replica?</p></li>
  <li><p>Can a replica attend more than one call at the same time?</p></li>
  <li><p>In the HPA specifications, for example here:</p></li>
  </ol>
  
  <pre><code>  - type: Resource
      resource:
        name: cpu
        target:
         type: Utilization
          averageUtilization: 50
  </code></pre>
  
  <p>What is this 50%? Is it 50% of the CPU of the pod or of the cluster?</p>
  
  <p>Thanks in advance for your help!</p>