The difference between the ADD and COPY Dockerfile commands. ADD does some magic stuff (like extracting files out of an archive) but is deprecated because it was sometimes a bit too magic. COPY does what it says on the tin and is the recommended way to do things now.
How to run a Python Flask app in Docker. The development server only listens to requests on 127.0.0.1 by default, and it turns out that when requests come into the container through the Docker bridge, they don’t get forwarded to 127.0.0.1.
MongoDB has a change streams feature, which allows an application to receive a notification of any database write, without having to poll for changes.
The MongoDB $lookup stage can take let and pipeline parameters, which can be used to perform a subquery and append the results to the return document. I’m looking forward to experimenting with this some more.
I really enjoyed this talk about the Lean Web by Chris Ferdinandi. As a user I’ve never been a fan of the single-page app approach to simple static sites, and I like the example of using a service worker to pre-fetch all the other content the user might want to see instead.