jsonnet VS s6

jsonnet[1] and kapitan[2] are the tools I currently use. Their learning curve is not optimal (and I tried to contribute to smoothen it with a jsonnet course[3] and a 'get started wit kapitan' blog post[4]), but once used to it it's hard to do without, and their combination makes them even more useful (esp. if you deploy K8s).

In Ruud's case, Jsonnet might have been worth looking at as Hashicorp tools can be configured with json in addition to HCL. But that would have been less fun I guess ;-)

I hope for Ruud it finds its niche, there's quite some competition in this field!

1: https://jsonnet.org/

Kubernetes config is a decent example. I had ChatGPT generate a representative silly example -- the content doesn't matter so much as the structure:

https://gist.github.com/cstrahan/528b00cd5c3a22e3d8f057bb1a7...

Now consider 100s (if not 1000s) of such files.

I haven't given Pkl an in depth look yet, but I can say that the Industry Standard™ of "simple YAML" + string substitution (with delicate, error prone indentation -- since YAML is indentation sensitive) is easily beat by any of:

- https://jsonnet.org/

- https://nickel-lang.org/

- https://nixos.org/manual/nix/stable/language/index.html

- https://dhall-lang.org/

- (insert many more here, probably including Pkl)

jsonnet cli: link

Jsonnet: A data template language implemented in C++, suitable for application and tool developers, can generate configuration data and organize, simplify and manage large configurations without side effects.

[Language: Jsonnet] (on GitHub)

Maybe you'd like jsonnet: https://jsonnet.org/

I find it particularly useful for configurations that often have repeated boilerplate, like ansible playbooks or deploying a bunch of "similar-but" services to kubernetes (with https://tanka.dev).

Dhall is also quite interesting, with some tradeoffs: https://dhall-lang.org/

A few years ago I did a small comparison by re-implementing one of my simpler ansible playbooks: https://github.com/retzkek/ansible-dhall-jsonnet

Apologies for the lack of context, and for missing this comment until today.

Both are tools for defining kubernetes manifests (which are YAML) in a reusable manner.

Jsonnet is a formally specified extension of JSON. It’s essentially a functional programming language (w/some object oriented features) that generates config files in JSON/YAML/etc, so it’s straightforward to determine whether an input file is valid, and to throw an error that points to an exact line if it’s not. It has a high learning curve, especially for people whose only experience is with imperative languages.

https://jsonnet.org/

Helm charts also generate YAML/JSON config files, but they use Go templating. This is easier and faster to understand, since it’s mostly string substitution and not much logic (there’s conditionals, iterators, and very basic helper functions). Unfortunately a simple typo or mistake can cause errors that are difficult to diagnose (the message may indicate a problem far away in code from the actual mistake). It can also generate output that’s valid according to the string templating rules, but not what was intended, which can be very confusing to debug.

Despite these shortcomings, the vast majority of kubernetes applications are distributed as helm charts. I understand why things ended up this way, but I still wish it were more common for people to invest the upfront effort to learn the superior tool, so it could be more widespread.

I like Google's Jsonnet [1], which has all of this except for 4.

Jsonnet is quite mature, with fairly wide language adoption, and has the benefit of supporting expressions, including conditionals, arithmetic, as well as being able to define reusable blocks inside function definitions or external files.

It's not suitable as a serialization format, but great for config. It's popular in some circles, but I'm sad that it has not reached wider adoption.

[1] https://jsonnet.org/

A (rare) good critique to systemd can be found here. Written by the developer behind s6, which happens to be scheduled to replace OpenRC on Alpine Linux. For completeness-sake, some of the main reasons why Alpine doesn't prefer systemd do not apply on most other distros.

It got mass-adopted while being imperfect, so that's to be expected. Thankfully its inception and the criticism that followed have paved the way for the likes of dinit and s6.

this page and this page, both by Laurent Bercot, creator of s6.

Of the two I have experience with, runit is simpler and thus easier to get the hang of than s6-rc/s6. Though the s6 (not s6-rc) docs at the author's site contain a lot of info (including apologetics and rationales) that applies almost equally well to runit

systemd: Yes; it's awaiting its "PipeWire". Thankfully, the likes of s6 and dinit are very promising. Though I can actually appreciate that systemd is addressed. As ultimately it helps in raising awareness that will benefit whatever software will replace it eventually.

Arguably this is less troublesome to solve compared to the other concerns. As we're inevitably waiting for the system supervision suite that will be to systemd what PipeWire has been to PulseAudio. I'm very optimistic about this as both s6 and Dinit are shaping up lovely.

Using the s6-service add command I added a service called "libvertd" when I ment to put "libvirtd". Now when I run s6-db-reload it spits out a error message saying "undefined service name libvertd". But I cant remove it using s6-service remove libvertd because that just spits out a generic help message and doesn't change anything. I also couldn't find documentation on https://skarnet.org/software/s6/ or https://skarnet.org/software/s6-rc/ as the command just *doesn't* exist on those pages. (also no man or info page).