Add support for structType marker

It maps to x-kubernetes-map-type in the openapi schema, similar to the
mapType marker.

Author: Maria Ntalla

pkg/crd/markers/topology.go

@@ -32,6 +32,8 @@ var TopologyMarkers = []*definitionWithHelp{
 		WithHelp(ListType("").Help()),
 	must(markers.MakeDefinition("mapType", markers.DescribesField, MapType(""))).
 		WithHelp(MapType("").Help()),
+	must(markers.MakeDefinition("structType", markers.DescribesField, StructType(""))).
+		WithHelp(StructType("").Help()),
 }
 
 func init() {
@@ -81,6 +83,22 @@ type ListMapKey string
 //   Any changes have to replace the entire map.
 type MapType string
 
+// +controllertools:marker:generateHelp:category="CRD processing"
+
+// StructType specifies the level of atomicity of the struct;
+// i.e. whether each field in the struct is independent of the others,
+// or all fields are treated as a single unit.
+//
+// Possible values:
+//
+// - "granular": fields in the struct are independent of each other,
+//   and can be manipulated by different actors.
+//   This is the default behavior.
+//
+// - "atomic": all fields are treated as one unit.
+//   Any changes have to replace the entire struct.
+type StructType string
+
 func (l ListType) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
 	if schema.Type != "array" {
 		return fmt.Errorf("must apply listType to an array")
@@ -120,3 +138,18 @@ func (m MapType) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
 
 	return nil
 }
+
+func (s StructType) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
+	if schema.Type != "object" && schema.Type != "" {
+		return fmt.Errorf("must apply structType to an object; either explicitly set or defaulted through an empty schema type")
+	}
+
+	if s != "atomic" && s != "granular" {
+		return fmt.Errorf(`StructType must be either "granular" or "atomic"`)
+	}
+
+	p := string(s)
+	schema.XMapType = &p
+
+	return nil
+}

pkg/crd/markers/zz_generated.markerhelp.go

@@ -136,6 +136,10 @@ type CronJobSpec struct {
 	// A map that allows different actors to manage different fields
 	// +mapType=granular
 	MapOfInfo map[string][]byte `json:"mapOfInfo"`
+
+	// A struct that can only be entirely replaced
+	// +structType=atomic
+	StructWithSeveralFields NestedObject `json:"structWithSeveralFields"`
 }
 
 type NestedObject struct {

pkg/crd/testdata/cronjob_types.go

@@ -125,13 +125,6 @@ spec:
                   a pointer to distinguish between explicit zero and not specified.
                 format: int32
                 type: integer
-              mapOfInfo:
-                description: A map that allows different actors to manage different fields
-                type: object
-                x-kubernetes-map-type: granular
-                additionalProperties:
-                  format: byte
-                  type: string
               jobTemplate:
                 description: Specifies the job that will be created when executing
                   a CronJob.
@@ -4993,6 +4986,13 @@ spec:
                     - template
                     type: object
                 type: object
+              mapOfInfo:
+                description: A map that allows different actors to manage different fields
+                type: object
+                x-kubernetes-map-type: granular
+                additionalProperties:
+                  format: byte
+                  type: string
               noReallySuspend:
                 description: This flag is like suspend, but for when you really mean
                   it. It helps test the +kubebuilder:validation:Type marker.
@@ -5017,6 +5017,18 @@ spec:
                   type: array
                 description: This tests string slices are allowed as map values.
                 type: object
+              structWithSeveralFields:
+                description: A struct that can only be entirely replaced
+                type: object
+                x-kubernetes-map-type: atomic
+                properties:
+                  bar:
+                    type: boolean
+                  foo:
+                    type: string
+                required:
+                - bar
+                - foo
               successfulJobsHistoryLimit:
                 description: The number of successful finished jobs to retain. This
                   is a pointer to distinguish between explicit zero and not specified.
@@ -5064,6 +5076,7 @@ spec:
             - mapOfInfo
             - patternObject
             - schedule
+            - structWithSeveralFields
             - twoOfAKindPart0
             - twoOfAKindPart1
             - unprunedEmbeddedResource