Which resources to learn more about Rails, Docker and Ember.js?

This is a pretty savvy bunch. What resources did you use to learn those parts of the stack? There is a ton of stuff out there so before I tried to consume it all I thought I’d ask. Curious to see what those in dev think are good options. For the last several years I’ve been doing hardware, Linux on SOC, Arduino with some Node, Python and Swift to support the hardware implementations. I’m an old so I like books/ebooks (like ORA) but vids are good too. I’m not going to code per se but want to go in depth on the syntax, methods and various ways to implement with the goal to be able to troubleshoot and look at the parts of the stack and know what’s going on. I still have a few brain cells left so I’m able to some heavy lifting to be able to learn.