One reason I believe made Unix and Linux are very successful is their philosophy that “Everything is a file”. But the reason that this philosophy made them successful is files are relatively static than other things (Windows registry anyone?), in my opinion.
Another example would be for certain data that changes infrequently, simply put them in a static file and do a code change is much better than save in a database. Even though a code change and re-deploy is needed when change happens, but the performance and reliability is much better. A lot of time, I’ve seen people try to boost the performance by introduce caching at all levels thinking they get the good part from both: flexibility and the performance. Well what they got is complexity since cache invalidation is the second most difficult thing in computer engineering (right after naming things) according to Phil Karlton. One interesting story that I experienced first handed: One day, we accidentally stopped a service that has been running without any issue for 6 month. We thought, OK, let’s just re-start it. But it won’t, giving errors about cannot read a url. Turns out it is trying to do a one time load of some static data from an external team. The developer did not want to write a static file so he gave the justification that this is dynamic if the other team changed the data, we just need to restart the service. The other team had no idea this service depends on this url to start. There is completely no traffic on that and they removed it together with bunch of things 5 months ago.
Lastly, I have been trying to do a dev op work whole day today. I need to start a MariaDB Galera cluster. Our company’s setup script has evolved over the years from Chef to Puppet to finally Salt. I copied a set of working salt script to setup MariaDB Galera cluster from another team, but ended up reading everything in it try to understand what are the dynamic things it is doing based on host name, configurations, etc. I really wish that we are using Docker right now, because it is a file, it is static. Pull a image is basically copy paste a file. It is much much faster and guaranteed works.