feat: add immutable marker (#660)

* feat: add immutable marker

* refactor: changed switch to if/else

* add: immutable marker documentation

Author: Soumya-Vaidya

pkg/simpleschema/markers.go

@@ -55,12 +55,14 @@ const (
 	MarkerTypeValidation MarkerType = "validation"
 	// MarkerTypeEnum represents the `enum` marker.
 	MarkerTypeEnum MarkerType = "enum"
+	// MarkerTypeImmutable represents the `immutable` marker.
+	MarkerTypeImmutable MarkerType = "immutable"
 )
 
 func markerTypeFromString(s string) (MarkerType, error) {
 	switch MarkerType(s) {
 	case MarkerTypeRequired, MarkerTypeDefault, MarkerTypeDescription,
-		MarkerTypeMinimum, MarkerTypeMaximum, MarkerTypeValidation, MarkerTypeEnum:
+		MarkerTypeMinimum, MarkerTypeMaximum, MarkerTypeValidation, MarkerTypeEnum, MarkerTypeImmutable:
 		return MarkerType(s), nil
 	default:
 		return "", fmt.Errorf("unknown marker type: %s", s)

pkg/simpleschema/markers_test.go

@@ -125,6 +125,15 @@ func TestParseMarkers(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			name:  "immutable marker with other markers",
+			input: "immutable=true required=false",
+			want: []*Marker{
+				{MarkerType: MarkerTypeImmutable, Key: "immutable", Value: "true"},
+				{MarkerType: MarkerTypeRequired, Key: "required", Value: "false"},
+			},
+			wantErr: false,
+		},
 	}
 
 	for _, tt := range tests {

pkg/simpleschema/transform.go

@@ -275,6 +275,20 @@ func (tf *transformer) applyMarkers(schema *extv1.JSONSchemaProps, markers []*Ma
 				},
 			}
 			schema.XValidations = validation
+		case MarkerTypeImmutable:
+			isImmutable, err := strconv.ParseBool(marker.Value)
+			if err != nil {
+				return fmt.Errorf("failed to parse immutable marker value: %w", err)
+			}
+			if isImmutable {
+				immutableValidation := []extv1.ValidationRule{
+					{
+						Rule:    "self == oldSelf",
+						Message: "field is immutable",
+					},
+				}
+				schema.XValidations = append(schema.XValidations, immutableValidation...)
+			}
 		case MarkerTypeEnum:
 			var enumJSONValues []extv1.JSON
 

pkg/simpleschema/transform_test.go

@@ -485,6 +485,73 @@ func TestBuildOpenAPISchema(t *testing.T) {
 			want:    nil,
 			wantErr: true,
 		},
+		{
+			name: "Simple immutable field",
+			obj: map[string]interface{}{
+				"id": "string | immutable=true",
+			},
+			want: &extv1.JSONSchemaProps{
+				Type: "object",
+				Properties: map[string]extv1.JSONSchemaProps{
+					"id": {
+						Type: "string",
+						XValidations: []extv1.ValidationRule{
+							{
+								Rule:    "self == oldSelf",
+								Message: "field is immutable",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "Simple immutable field with false value",
+			obj: map[string]interface{}{
+				"name": "string | immutable=false",
+			},
+			want: &extv1.JSONSchemaProps{
+				Type: "object",
+				Properties: map[string]extv1.JSONSchemaProps{
+					"name": {
+						Type: "string",
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "Immutable with other markers",
+			obj: map[string]interface{}{
+				"resourceId": `string | required=true immutable=true description="Unique resource identifier"`,
+			},
+			want: &extv1.JSONSchemaProps{
+				Type:     "object",
+				Required: []string{"resourceId"},
+				Properties: map[string]extv1.JSONSchemaProps{
+					"resourceId": {
+						Type:        "string",
+						Description: "Unique resource identifier",
+						XValidations: []extv1.ValidationRule{
+							{
+								Rule:    "self == oldSelf",
+								Message: "field is immutable",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "Invalid immutable value",
+			obj: map[string]interface{}{
+				"id": "string | immutable=invalid",
+			},
+			want:    nil,
+			wantErr: true,
+		},
 		{
 			name: "Custom simple type (required)",
 			obj: map[string]interface{}{

website/docs/docs/concepts/10-simple-schema.md

@@ -19,7 +19,7 @@ spec:
     kind: WebApplication
     spec:
       # Basic types
-      name: string | required=true description="My Name"
+      name: string | required=true immutable=true description="My Name"
       replicas: integer | default=1 minimum=1 maximum=100
       image: string | required=true
 
@@ -193,13 +193,15 @@ mode: string | enum="debug,info,warn,error" default="info"
 - `enum="value1,value2"`: Allowed values
 - `minimum=value`: Minimum value for numbers
 - `maximum=value`: Maximum value for numbers
+- `immutable=true`: Field cannot be changed after creation
 
 Multiple markers can be combined using the `|` separator.
 
 For example:
 
 ```yaml
 name: string | required=true default="app" description="Application name"
+id: string | required=true immutable=true description="Unique identifier"
 replicas: integer | default=3 minimum=1 maximum=10
 price: float | minimum=0.01 maximum=999.99
 mode: string | enum="debug,info,warn,error" default="info"