[wruza]

I never managed a fleet. I mean I occasionally manage up to 30 instances, does that count?

Either way, my notion about doing it properly is to have a set of scripts (ansible/terraform?) that rebuild the configuration from templates and rewrite, restart everything. Afaiu, there's no "let's turn that off by rm-ing and later turn it on again by cat<<EOF-ing", cause there's no state database that could track it, unless you rely on [ -e $path ], which feels not too straightforward for e.g. state monitoring.

(I do the same basically, but without ansible. Instead I write a builder script and then paste its output into the root shell. Poor man's ansible, but I'm fine.)

So as I understand it, these dirs are only really useful for manual management, not for fleets where you just re-apply your "provisioning", or what's the proper term, onto your instances, without temporary modifications. When you have a fleet, any state that is not in the "sources" becomes a big problem very quickly. And if you have "sources", there's no problem of turning section output on and off. For example when I need a change, I rebuild my scripts and re-paste them into corresponding instances. This ensures that if I lose any server to crash, hw failure, etc, all I have is to rent another one and right-click a script into its terminal.

So I believe that gp has a point, or at least that I don't get the rationale that replies to gp suggest itt. Feels not that important for automatic management.

[hnlmorg]

I’ve found the template system starts to have shortcomings if you need differences between different classes of systems within your fleet (eg VDIs for data scientists vs nodes in a ML pipeline pool)

Yeah a good templating language will allow you to apply conditionals but honestly, it’s just generally easier to have different files inside a config directory than have to manage all these different use cases in a single monolithic template or multiple different templates in which you need to remember to keep shared components in sync.

At the end of the day, we aren’t talking about solving problems that were impossible before but rather solving problems that were just annoying. It’s more a quality of life improvement than something that couldn’t be otherwise solved with enough time and effort.

[wruza]

I see, thanks for the explanation.

Although I think that it sounds so ansible, and that's exactly why I avoid using it. It is a new set of syntax, idioms, restrictions, gotchas, while all I need is a nodejs script that joins initialization template files together, controlled by json server specs. With first class ifs and fors, and without "code in config" nonsense. I mean, I know exactly what was meant to be done manually, I just need N-times parametrized automation, right? Also, my servers are non-homogeneous as well, and I don't think I ever had an issue with that.

[hnlmorg]

It’s not just Ansible. I’ve ran into this problem many times using many different configuration systems. Even in the old days of hand-rolling deployment scripts in Bash and Perl.

Managing files instead of one big monolithic config is just easier because there’s less chance of you foobarring something in a moment of absentmindedness.

But as I said, I’m not criticising your approach either. Templating your config is definitely a smart approach to the same problem too.

[wruza]

Not sure if I understand, because my templates are also multi-file and multi-js-module, where needed. It's only the result that is a single root-pasteable script (per server) which generates a single /etc/foo/foo_config file per service. So I think I'm lost again about changes.

You don't want instance-local changes. Do you? Afaiu, these changes are anti-pattern cause they do not persist in case of failure. You want to change the source templates and rebuild-repropagate the results. Having ./foo.d/nn-files is excessive and serves litte purpose in automated mode, unless you're dealing with clunky generators like ansible where you only have bash one-liners.

What am I missing?

[hnlmorg]

You’re not missing anything. A lot of the problem is due to clunky generators.

But then those clunky generators do solve different problems too. Though I’m not going to debate that topic here right now, besides saying no solution is perfect and thus choose a tech stack is always a question of choosing which tradeoffs you want to make.

However on the topic of monolithic config files vs config directories, the latter does provide more options for how to manage your config. So even if you have a perfect system for yourself which lends itself better for monolithic files, that doesn’t mean that config directories don’t make life a lot easier for a considerable number of other systems configurations.