Ask HN: Best resource for learning devops as an engineer (js/ruby)?

In my career I've been spoiled with terrific devops coworkers who have generally handled everything from code to deploy. As a result, I feel I lack in expertise about devops that I should know as an engineer. Sideprojects of mine end up going on PaaS services like Heroku or Zeit and I don't really learn what it means to set up a server. For instance, I could tell you that you likely have a load balancer (like nginx) which you can use to point routes to different services, and I know that services are going to be things like node instances running my code; but everything I know is fairly superficial and lacking in depth. What is the best way to share secrets? Is there a standard way of having your load balancer know what services to feed to? How does a load balancer that defines routes work with a rails or express instance that also defines routes? Should all my services be built on vagrant, or has docker made that less useful? I've been having trouble filling in these ga