There are many heavy weight solutions that you should look into if you become a team with many credentials including blackbox, https://www.chef.io/, https://square.github.io/keywhiz/. Can also have files encrypted on github with things like git-crypt
Simple Solutions
Environment Variables
easy load from file
often use env variables for other things too so good to set up
Cons:
According to https://news.ycombinator.com/item?id=9952911, its possible that environment variables are shown in debug output when a server crashes potentially comprising the system
Can't revoke secrets.json or manage like an expert
