feat: Add typed scale argument to derive macro

[Techassi]

Motivation

Customizing the scale subresource via #[kube(scale = r#"{}"#)] can feel very out-of-place and requires writing a raw JSON string. In addition, this can lead to a very long line, eg:

#[kube(
    version = "v1alpha1",
    kind = "MyScaler",
    namespaced,
    scale = r#"{"specReplicasPath": ".spec.replicas", "statusReplicaPath": ".status.replicas", "labelSelectorPath": ".spec.labelSelector"}"#
)]
struct ScalerSpec {}

Solution

This allows customizing the scale subresource by providing key-value items instead of a raw JSON string. For backwards-compatibility, it is still supported to provide a JSON string. However, all examples and tests were converted to the new format.

#[kube(
    version = "v1alpha1",
    kind = "MyScaler",
    namespaced,
    scale(
        specReplicasPath = ".spec.replicas",
        statusReplicaPath = ".status.replicas",
        labelSelectorPath = ".spec.labelSelector"
   )
)]
struct ScalerSpec {}

[codecov]

Codecov Report

Attention: Patch coverage is 76.36364% with 13 lines in your changes missing coverage. Please review.

Project coverage is 76.0%. Comparing base (6a980c6) to head (696d389).

Files with missing lines	Patch %	Lines
kube-derive/src/custom_resource.rs	76.0%	13 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1656     +/-   ##
=======================================
+ Coverage   75.9%   76.0%   +0.1%     
=======================================
  Files         84      84             
  Lines       7611    7664     +53     
=======================================
+ Hits        5771    5817     +46     
- Misses      1840    1847      +7     

Files with missing lines	Coverage Δ
kube-derive/src/lib.rs	0.0% <ø> (ø)
kube-derive/tests/crd_schema_test.rs	96.9% <ø> (ø)
kube-runtime/src/events.rs	98.1% <100.0%> (ø)
kube/src/lib.rs	88.5% <ø> (ø)
kube-derive/src/custom_resource.rs	84.1% <76.0%> (+0.7%)	⬆️

[clux]

Hey there. Thanks for this! Apologise for the delay.

I think this makes sense, given you've made it non-breaking, but ideally the dependency on the openapi crate should be severed if it's just for the interface. Have added a few suggestive comments.

[clux]

Maybe there's a way to add a deprecated message to the old way?

[Techassi]

As far as I know, there is no way to emit warning from within derive macros, only hard-errors, aka compile_error!().

[Techassi]

I instead opted to add a note to the relevant setion in the doc comment for the derive macro. See a56835e.

[Techassi]

Apologise for the delay.

No worries. I will shortly take a look at your comments. I will also see if we can get rid of the k8s_openapi dependency.

[Techassi]

Sorry for the delayed work on this, but I think I have addressed both of your biggest concerns in d93d708.

[clux]

I see most of the lines for this impl is showing up as untested. I think we can get easy coverage by adding the invocation to kube-derive/tests/crd_schema_test.rs and updating the schema changes in that file.

[Techassi]

Sure thing, I can add some tests to test both the old and the new way.

[Techassi]

Adding a test proved very valuable! Take a look at 696d389.

The addition also helps with coverage and greatly reduces the amount of missing lines. I have a few ideas how this can be improved even further in the future. I will create a PR for it soon.