Ask HN: Where can I learn about Docker in-depth

I'm having trouble finding a good resource for learning about Docker (& Kubernetes eventually). Most things I found are either very basic or outdated. I already know the basics (running simple containers with Dockerfiles etc.), and I want to learn about "strategies" involving containers too. I eventually want to be able to build a full dev environment, push containers (containing certain git branches) to staging etc.

Essentially, I'm looking for a good way to learn about how to use Docker in a real world-scenario.

Thanks!