DNS is for people, not for IT infrastructure

>Fortunately, we still have /etc/hosts, which we can easily provision

This is the kind of thing you read in a post-mortem and wonder how they designed something so fiendishly wonderful.

At 2:00am our MySQL master failed and failed over successfully to our secondary server. As part of post-failover ops, ansible playbook proceeded to login to 1000 instances to update the hosts file for the new master. This caused traffic amplication which caused our Etcd nodes to believe they were down. As the etcd nodes failed over, our ansible playbook proceeded to then login to 1000 instances to update the hosts file...

Honestly, whatever system you built is justing do the same exact function as DNS just with extra steps. If you squint really hard /etc/hosts is your local dns cache and ansible is your resolver. I think this kind of "simplification fetishization" is dangerously attractive to people who have only managed relatively simply setups. I don't think anyone who has ever had to deal with high-availability failover would consider Ansible a good solution.

The problem that so many people hit with DNS isn't specific to DNS the protocol - it's the problem of service discovery. This architecture doesn't eliminate service discovery, it just moves it to a far more brittle configuration.

One does not even need to squint. The first page of RFC 882 explains outright that the DNS came about in the first place because the mechanisms for updating a HOSTS.TXT file and publishing it to loads of places did not scale.

That's still just as true for the intranets of the 2020s with thousands of machines all downloading a HOSTS file several times a day (or even hour/minute) as it was for the Internet of July 1983 with around 500 hosts that was merely downloaded by everyone a couple of times per week. The fact that a file can be copied faster now is counterbalanced by the fact that tying this to real-time failover means that it needs to be updated and distributed several orders of magnitude more quickly than it was in 1983 too. And that's ignoring the linear nature of a HOSTS file lookup contrasted with even the stupidest DNS implementation.

Those who think that HOSTS is a fallback for any sort of dynamic operation (into and out of service) of even hundreds of machines have not learned the history of why the DNS even exists.

John Day talks about this a fair bit: what people want to do is naming of applications, in a way that makes it independent of addressing (i.e. where the application is running). DNS still names the machine — it's just a one-step abstracted machine addressing scheme, not an application naming scheme per se. Then we designed an ad-hoc protocol on top that associates applications with specific machine names (and port numbers): if you go to facebook.com:443 (a.k.a. https) you expect to find an instance of the Facebook application, not a webmail client or an SSH server.

This isn't how any of this was really supposed to work. Back in the day the application identifier was the _port number_, according to a big list maintained by ICANN. The idea was that you could go to a machine (identified by IP or more conveniently by DNS) and see if it was running an instance of the ‘Facebook’ application, i.e. you'd find Facebook not at facebook.com:https but at meta.com:facebook. The end goal was to eliminate the need for the former part at some point, and come up with a better way of looking up applications than distributing a list by email. Instead the application ID is now used for transport and the host name instead encodes application ID, which it was never meant for, and that's why we can't have nice things (like device mobility).

>The first page of RFC 882 explains outright that the DNS came about in the first place because the mechanisms for updating a HOSTS.TXT file and publishing it to loads of places did not scale.

Great piece of history. The RFC is a bit older than I am so I've never studied it. Looking at it that way, then OP has just re-invented DNS.

Why bother with all the issues and difficulties of hosting a web server when I can just SCP all the files to everyone's computers constantly?