Kubernetes is deprecating Docker as a container runtime after v1.20. Don’t Panic 😱 Docker containers are still supported, but the dockershim/Docker, the layer between Kubernetes and containerd is deprecated and will be removed from version 1.22+.
https://kubernetes.io/blog/2020/12/02/dont-panic-kubernetes-and-docker/"
So if you are running docker you need to change to a supported container runtime interface (CRI). containerd is a good choice, it is already running on your Kubernetes node if you are running Docker....
Running a mailserver in Kubernetes
Running a webserver in Kubernetes is easy, but a mailserver is more challenging. Most of the challenging things has todo with your ip infrastructure, ingress and loadbalancer within Kubernetes. Here are things I learned when I was deploying a mailserver based on Postfix on Kubernetes with metallb and nginx ingress. If you have a different setup, things could apply or not.
Prevent mail loops on your secondary MX Your postfix MX pod is running maybe on a private ip RFC1918, this is fine....
Varnish in Kubernetes
This is a simple minimal but highly configurable Varnish caching service for Kubernetes. This should be placed between your ingress and your application service.
simple setup
It can be used in combination with multiple ingresses and application services at the same time.
multiple ingress and services
Setup Apply the following yaml file, replicas and environment variables can be adjusted to your need....
