kapp VS dhall

If you want to take it one step further: you might be applying several resources at a time that are logically one "application". kapp (https://carvel.dev/kapp/) lets you group those together and give them a name, and provides a "terraform-like" experience where it shows you its execution plan before applying updates. So then you might do `ytt -f | kapp deploy -a name-of-thing` Or you could use helm's templating engine but then still pass the resulting yaml to kapp for its unification of the deployment step.

since you mentioned Kubernetes...

> It would be nice if there was a separate state reconciliation system that one could adapt to use with Cue or Dhall or any other frontend

this exactly was thinking behind https://carvel.dev/kapp for Kubernetes (i'm one of the maintainers). it makes a point to not know how you decided to generate your Kubernetes config -- just takes it as input.

> In particular the ability to import other files as semantic hashes seems like a great feature.

it's an interesting feature but seems like it should be unnecessary given that config can be easily checked into git (your own and its dependencies).

i think kubernetes is not a great example in favor of more client state (like tf) since k8s has uniform resource structure (metadata.*) and first class labeling support. but as you point out kubectl doesnt use labels well (at least imho).

when building https://carvel.dev/kapp (which i think of as "optimized terraform" for k8s) the goal was absolutely to take advantage of those k8s features. we ended up providing two capabilities: direct label (more advanced) and "app name" (more user friendly). from impl standpoint, difference is how much state is maintained.

"kapp deploy -a label:x=y -f ..." allows user to specify label that is applied to all deployed resources and is also used for querying k8s to determine whats out there under given label. invocation is completely stateless since burden of keeping/providing state (in this case the label x=y) is shifted to the user. downside of course is that all apis within k8s need to be iterated over. (side note, fun features like "kapp delete -a label:!x" are free thanks to k8s querying).

"kapp deploy -a my-app -f ..." gives user ability to associate name with uniquely auto-generated label. this case is more stateful than previous but again only label needs to be saved (we use ConfigMap to store that label). if this state is lost, one has to only recover generated label.

imho k8s api structure enables focused tools like kapp to be much much simpler than more generic tool like terraform. as much as i'd like for terraform to keep less state, i totally appreciate its needs to support lowest common denominator feature set.

common discussion topics:

Take a look at kapp (https://github.com/vmware-tanzu/carvel-kapp).

kapp - Install, upgrade, and delete multiple Kubernetes resources as one "application"

I really like this approach for simplifying Kubernetes. A few projects similar to OAM in that it provides a higher level "Application" CRD:

https://github.com/vmware-tanzu/carvel-kapp

```

If you mean installing Dhall's dependencies (https://github.com/dhall-lang/dhall-haskell/blob/master/dhal...), those aren't too crazy, but they're definitely not all "beginner level". Template Haskell in particular is quite heavyweight.

Ok, lets be specific. Lets write a comment to explain this function:

https://github.com/dhall-lang/dhall-haskell/blob/master/dhal...

I haven't tried it but apparently you can compile to Nix from Dhall:

> You can use this compiler to program Nix using the Dhall language. This package targets people who wish Nix had a type system.

https://github.com/dhall-lang/dhall-haskell/tree/master/dhal...

If the problem is the syntax and people wants some other format that compiles to nix, there's dhall

https://dhall-lang.org/

https://github.com/dhall-lang/dhall-haskell/tree/master/dhal...

https://www.haskellforall.com/2017/01/typed-nix-programming-...

Dhall is a generic config language with some programming capabilities (but not turing complete) that can compile to json, yaml, and other formats, like in this instance nix.

For my GSoC project, I built from scratch the dhall-csv package on the Dhall Haskell implementation Github Repository. Said package provides two executables, dhall-to-csv (which converts Dhall files into CSV files) and csv-to-dhall (which converts CSV files into Dhall files). It also provides Haskell libraries with the functions that translate bidirectionally between Dhall and CSV.

> If you add constraints (like not being able to feed the program to itself as is done in the halting problem and not allowing unbounded loops) then it is possible to determine if a program will terminate or not.

Dhall is a good example - https://github.com/dhall-lang/dhall-haskell .

See also https://dhall-lang.org/

That just seems like an even greater nightmare to me. Soon you would have to learn to read and understand a custom program in a Turing-complete language for each and every installation.

The proper solution is a DSL, just a better DSl. Or perhaps a DSL embedded in something like dhall <https://dhall-lang.org/>, but definitely not a general-purpose programming language.

Dhall