jsonnet VS strictyaml

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/

NestedText already is the way I use YAML; everything is intepreted as a string. I have some trust in my YAML parser to not mangle most strings. I could use NestedText, but users would be unfamiliar with it, and IIRC the only parsers are in Python. But then I could use StrictYaml too https://github.com/crdoconnor/strictyaml

you can stick to a subset of YAML syntax (e.g. strictYAML)

YAML stands for "YAML Ain’t Markup Language" - this is known as a recursive acronym. YAML is often used for writing configuration files. It’s human readable, easy to understand and can be used with other programming languages. Although YAML is commonly used in many disciplines, it has received criticism on the amoutn of whitespace .yml files have, difficulty in editing, and complexity of the standard. Despite the criticism, properly using YAML ensures that you can reproduce the results of a project and makes sure that the virtual environment packages play nicely with system packages. (If you're looking for another way to share environments there are other alternatives to YAML which include StrictYAML (a type-safe YAML parser) and NestedText)

The example you linked provides this as an example of a YAML document that he wants his format to support.

That safe subset exists and is implemented in a number of languages. It is called strict-yaml: https://hitchdev.com/strictyaml/

StrictYAML\ (33 comments)

To me those are in the category of "nice to have", and the problem is that every developer has different preferences for these [1] [2]. But the main features of StrictYaml, like supporting comments and less syntactic noise, I think are pretty uncontroversial, and perhaps it's worth it to get people to switch over for those alone. It doesn't need to be perfect, it just needs to be a significant enough improvement over JSON, and I'd say those two features are more than enough

[1]: https://github.com/crdoconnor/strictyaml/issues/37

[2]: https://github.com/crdoconnor/strictyaml/issues/38