title: How to setup up DNS and ingress-controllers for a public facing web app?
body: <p>I'm trying to understand the concepts of ingress and ingress controllers in kubernetes. But I'm not so sure what the end product should look like. Here is what I don't fully understand:</p>
  
  <p>Given I'm having a running Kubernetes cluster somewhere with a master node which runes the control plane and the etcd database. Besides that I'm having like 3 worker nodes - each of the worker nodes has a public IPv4 address with a corresponding DNS A record (<code>worker{1,2,3}.domain.tld</code>) and I've full control over my DNS server. I want that my users access my web application via <code>www.domain.tld</code>. So I point the the <code>www</code> CNAME to one of the worker nodes (I saw that my ingress controller i.e. got scheduled to worker1 one so I point it to <code>worker1.domain.tld</code>).</p>
  
  <p>Now when I schedule a workload consisting of 2 frontend pods and 1 database pod with 1 service for the frontend and 1 service for the database. From what've understand right now, I need an ingress controller pointing to the frontend service to achieve some kind of load balancing. Two questions here:</p>
  
  <ol>
  <li><p>Isn't running the ingress controller only on one worker node pointless to internally load balance two the two frontend pods via its service? Is it best practice to run an ingress controller on every worker node in the cluster?</p></li>
  <li><p>For whatever reason the worker which runs the ingress controller dies and it gets rescheduled to another worker. So the ingress point will get be at another IPv4 address, right? From a user perspective which tries to access the frontend via <code>www.domain.tld</code>, this DNS entry has to be updated, right? How so? Do I need to run a specific kubernetes-aware DNS server somewhere? I don't understand the connection between the DNS server and the kubernetes cluster.</p></li>
  </ol>
  
  <p>Bonus question: If I run more ingress controllers replicas (spread across multiple workers) do I do a DNS-round robin based approach here with multiple IPv4 addresses bound to one DNS entry? Or what's the best solution to achieve HA. I rather not want to use load balancing IP addresses where the worker share the same IP address.</p>