fix: Fix the internal CluserConfig type used for provider-agnostic logic (#607)

Spotted in discussions with @dkoshkin about internal usage of types like
this as opposed to type switches.

Author: jimmidyson

pkg/common/clusterconfig/types.go

@@ -5,12 +5,31 @@ package clusterconfig
 
 import carenv1 "github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/api/v1alpha1"
 
+// ClusterConfig is a type to be used internally to simplify the handling of cluster configurations for different
+// providers. It is not meant to be used as a CRD.
+// By including all the possible configurations for all the providers, we can easily switch between providers in code
+// without type assertions/switches and avoids passing around `interface{}` or `any` types.
+// Every provider-specific cluster config variable will successfully unmarshal to this type and so it is safe to use
+// this internally when a handler provides functionality for multiple providers but exhibits different behaviour per
+// provider.
 type ClusterConfig struct {
 	AWS *carenv1.AWSSpec `json:"aws,omitempty"`
 
-	Docker *carenv1.AWSSpec `json:"doker,omitempty"`
+	Docker *carenv1.DockerSpec `json:"docker,omitempty"`
 
 	Nutanix *carenv1.NutanixSpec `json:"nutanix,omitempty"`
 
 	carenv1.GenericClusterConfigSpec `json:",inline"`
+
+	ExtraAPIServerCertSANs []string `json:"extraAPIServerCertSANs,omitempty"`
+
+	ControlPlane *ControlPlaneConfig `json:"controlPlane,omitempty"`
+}
+
+type ControlPlaneConfig struct {
+	AWS *carenv1.AWSControlPlaneNodeSpec `json:"aws,omitempty"`
+
+	Docker *carenv1.DockerNodeConfigSpec `json:"docker,omitempty"`
+
+	Nutanix *carenv1.NutanixNodeConfigSpec `json:"nutanix,omitempty"`
 }