[majewsky]

> Docker restricts the container to a single process only.

This is definitely not true. I'm running syslogd inside a container (next to the actual process) without any trouble.

> ssh

I'll take `kubectl exec` over SSH any-time because it's a much more plausible way to handle credentials. Also, it does not require an always-running daemon inside the container, which reduces the TCB and the memory footprint.

> Take a simple application like WordPress. You would need to build 3 containers that consume services from each other.

It's not required, but it's a good practice to take advantage of the capabilities of your container orchestration software of choice.

> a MySQL container plus [...] separate containers for persistent data for the Mysql DB

Why would you need a separate container for data? The thing you're looking for is a "volume" (in the simplest case just a bind-mount from the host into the container, as you even explain further down).