feat(versioned): Add support to pass the scale argument

Author: Techassi

crates/stackable-versioned-macros/src/attrs/container.rs

@@ -50,6 +50,7 @@ pub struct ContainerSkipArguments {
 ///   cluster scoped resource.
 /// - `crates`: Override specific crates.
 /// - `status`: Set the specified struct as the status subresource.
+/// - `scale`: Configure the scale subresource for horizontal pod autoscaling integration.
 /// - `shortname`: Set a shortname for the CR object. This can be specified multiple
 ///   times.
 /// - `skip`: Controls skipping parts of the generation.
@@ -64,7 +65,7 @@ pub struct StructCrdArguments {
     pub status: Option<Path>,
     // derive
     // schema
-    // scale
+    pub scale: Option<Scale>,
     // printcolumn
     #[darling(multiple, rename = "shortname")]
     pub shortnames: Vec<String>,
@@ -74,3 +75,21 @@ pub struct StructCrdArguments {
     // annotation
     // label
 }
+
+/// Scale subresource configuration for a CRD.
+///
+/// Mirrors the fields of [`k8s_openapi::CustomResourceSubresourceScale`][1] and what is present in
+/// `kube_derive`.
+///
+/// [1]: k8s_openapi::apiextensions_apiserver::pkg::apis::apiextensions::v1::CustomResourceSubresourceScale
+//
+// TODO (@Techassi): This should eventually get replaced by directly using what `kube_derive` offers,
+// but that requires an upstream restructure I'm planning to do soon(ish).
+#[derive(Clone, Debug, FromMeta)]
+pub struct Scale {
+    pub spec_replicas_path: String,
+    pub status_replicas_path: String,
+
+    #[darling(default)]
+    pub label_selector_path: Option<String>,
+}

crates/stackable-versioned-macros/src/codegen/container/struct/mod.rs

@@ -272,6 +272,21 @@ impl Struct {
             _ => None,
         };
 
+        let scale = spec_gen_ctx.kubernetes_arguments.scale.as_ref().map(|s| {
+            let spec_replicas_path = &s.spec_replicas_path;
+            let status_replicas_path = &s.status_replicas_path;
+            let label_selector_path = s
+                .label_selector_path
+                .as_ref()
+                .map(|p| quote! { , label_selector_path = #p });
+
+            quote! { , scale(
+                spec_replicas_path = #spec_replicas_path,
+                status_replicas_path = #status_replicas_path
+                #label_selector_path
+            )}
+        });
+
         let shortnames: TokenStream = spec_gen_ctx
             .kubernetes_arguments
             .shortnames
@@ -286,7 +301,7 @@ impl Struct {
                 // These must be comma separated (except the last) as they always exist:
                 group = #group, version = #version, kind = #kind
                 // These fields are optional, and therefore the token stream must prefix each with a comma:
-                #singular #plural #namespaced #crates #status #shortnames
+                #singular #plural #namespaced #crates #status #scale #shortnames
             )]
         })
     }