pkg/crd: support validating internal list items on list types

Fixes #342

Signed-off-by: Alexander Yastrebov <alexander.yastrebov@zalando.de>

pkg/crd/markers/validation.go

@@ -288,6 +288,15 @@ func isIntegral(value float64) bool {
 	return value == math.Trunc(value) && !math.IsNaN(value) && !math.IsInf(value, 0)
 }
 
+func thisOrItemsSchema(schema *apiext.JSONSchemaProps) *apiext.JSONSchemaProps {
+	if schema.Type == "array" &&
+		schema.Items != nil &&
+		schema.Items.Schema != nil {
+		return schema.Items.Schema
+	}
+	return schema
+}
+
 // +controllertools:marker:generateHelp:category="CRD validation"
 // XValidation marks a field as requiring a value for which a given
 // expression evaluates to true.
@@ -359,17 +368,19 @@ func (m MultipleOf) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
 }
 
 func (m MaxLength) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
+	schema = thisOrItemsSchema(schema)
 	if schema.Type != "string" {
-		return fmt.Errorf("must apply maxlength to a string")
+		return fmt.Errorf("must apply maxlength to a string or a string array")
 	}
 	val := int64(m)
 	schema.MaxLength = &val
 	return nil
 }
 
 func (m MinLength) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
+	schema = thisOrItemsSchema(schema)
 	if schema.Type != "string" {
-		return fmt.Errorf("must apply minlength to a string")
+		return fmt.Errorf("must apply minlength to a string or a string array")
 	}
 	val := int64(m)
 	schema.MinLength = &val
@@ -380,8 +391,9 @@ func (m Pattern) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
 	// Allow string types or IntOrStrings. An IntOrString will still
 	// apply the pattern validation when a string is detected, the pattern
 	// will not apply to ints though.
+	schema = thisOrItemsSchema(schema)
 	if schema.Type != "string" && !schema.XIntOrString {
-		return fmt.Errorf("must apply pattern to a `string` or `IntOrString`")
+		return fmt.Errorf("must apply pattern to a string or IntOrString or an array of them")
 	}
 	schema.Pattern = string(m)
 	return nil
@@ -510,6 +522,7 @@ func (m XEmbeddedResource) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
 // which means the "XIntOrString" marker *must* be applied first.
 
 func (m XIntOrString) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
+	schema = thisOrItemsSchema(schema)
 	schema.XIntOrString = true
 	return nil
 }

pkg/crd/testdata/cronjob_types.go

@@ -252,6 +252,24 @@ type CronJobSpec struct {
 
 	// Checks that arrays work when the type contains a composite literal
 	ArrayUsingCompositeLiteral [len(struct{ X [3]int }{}.X)]string `json:"arrayUsingCompositeLiteral,omitempty"`
+
+	// This tests string slice item validation.
+	// +kubebuilder:validation:MinLength=1
+	// +kubebuilder:validation:MaxLength=255
+	// +kubebuilder:validation:Pattern=^[a-z0-9]([-a-z0-9]*[a-z0-9])?([.][a-z0-9]([-a-z0-9]*[a-z0-9])?)*$
+	Hosts []string `json:"hosts,omitempty"`
+
+	HostsAlias Hosts `json:"hostsAlias,omitempty"`
+
+	// This tests string alias slice item validation.
+	LongerStringArray []LongerString `json:"longerStringArray,omitempty"`
+
+	// This tests that a slice of IntOrString can also have a pattern attached to it.
+	// This can be useful if you want to limit the string to a perecentage or integer.
+	// The XIntOrString marker is a requirement for having a pattern on this type.
+	// +kubebuilder:validation:XIntOrString
+	// +kubebuilder:validation:Pattern="^((100|[0-9]{1,2})%|[0-9]+)$"
+	IntOrStringArrayWithAPattern []*intstr.IntOrString `json:"intOrStringArrayWithAPattern,omitempty"`
 }
 
 type ContainsNestedMap struct {
@@ -360,6 +378,12 @@ type LongerString string
 // TotallyABool is a bool that serializes as a string.
 type TotallyABool bool
 
+// This tests string array item validation.
+// +kubebuilder:validation:MinLength=1
+// +kubebuilder:validation:MaxLength=255
+// +kubebuilder:validation:Pattern=^[a-z0-9]([-a-z0-9]*[a-z0-9])?([.][a-z0-9]([-a-z0-9]*[a-z0-9])?)*$
+type Hosts []string
+
 func (t TotallyABool) MarshalJSON() ([]byte, error) {
 	if t {
 		return []byte(`"true"`), nil

pkg/crd/testdata/testdata.kubebuilder.io_cronjobs.yaml

@@ -196,12 +196,40 @@ spec:
                 description: This tests that exported fields are not skipped in the
                   schema generation
                 type: string
+              hosts:
+                description: This tests string slice item validation.
+                items:
+                  maxLength: 255
+                  minLength: 1
+                  pattern: ^[a-z0-9]([-a-z0-9]*[a-z0-9])?([.][a-z0-9]([-a-z0-9]*[a-z0-9])?)*$
+                  type: string
+                type: array
+              hostsAlias:
+                description: This tests string array item validation.
+                items:
+                  maxLength: 255
+                  minLength: 1
+                  pattern: ^[a-z0-9]([-a-z0-9]*[a-z0-9])?([.][a-z0-9]([-a-z0-9]*[a-z0-9])?)*$
+                  type: string
+                type: array
               int32WithValidations:
                 format: int32
                 maximum: 2
                 minimum: -2
                 multipleOf: 2
                 type: integer
+              intOrStringArrayWithAPattern:
+                description: |-
+                  This tests that a slice of IntOrString can also have a pattern attached to it.
+                  This can be useful if you want to limit the string to a perecentage or integer.
+                  The XIntOrString marker is a requirement for having a pattern on this type.
+                items:
+                  anyOf:
+                  - type: integer
+                  - type: string
+                  pattern: ^((100|[0-9]{1,2})%|[0-9]+)$
+                  x-kubernetes-int-or-string: true
+                type: array
               intOrStringWithAPattern:
                 anyOf:
                 - type: integer
@@ -6609,6 +6637,14 @@ spec:
                 - bar
                 - foo
                 type: object
+              longerStringArray:
+                description: This tests string alias slice item validation.
+                items:
+                  description: This tests that markers that are allowed on both fields
+                    and types are applied to types
+                  minLength: 4
+                  type: string
+                type: array
               mapOfArraysOfFloats:
                 additionalProperties:
                   items: