Helm chart for Kubernetes installation

[acim]

Use case

Kubernetes installation.

Your idea for a solution

I have made a chart for my usage and it may also be fine for others at least fine to begin with.

• I'm willing to help with the implementation

[foxcpp]

I'm not familiar with Kubernetes so I can't maintain corresponding configurations. Furthermore, I don't believe maddy in its current state is suitable for automatic multi-instance deployment.

Nonetheless, I probably can accept a PR with all necessary stuff being added into "contrib/kubernetes" directory. These would go with the disclaimer "community contribution, not officially supported". (Footnote: make a PR against dev branch).

[acim]

Well, such traditional services like SMTP and IMAP are also not that easy to transform to the cloud environment, so I really did not do so. What I did is just to make easy to install Maddy on existing Kubernetes cluster. In Kubernetes, you can install application in three different ways:

• StatefulSet - usually used for databases, this is good candidate for Maddy as well because it has to keep important data
• DaemonSet - one instance on each node, also good candidate but it means you need a TCP load balancer in front of them which further means you are an enterprice so you probably want to use some enterprise mailing system (not saying that Maddy is not good, on the contrary, but they are looking for commercial stuff)
• Deployment - this is the most common way and I have chosen this one because it is the easiest. However, there are negative sides of this which me may discuss, but at least it works and my opinion is that something is better than nothing 👍

If this is still interesting, I can contribute it and also take care of future maintenance in case of feature requests of bugs.

[foxcpp]

If you think it is useful - feel free to make a PR as described in my previous message.

[acim]

CR please: #278