# io.k8s.api.admissionregistration.v1alpha1.JSONPatch

From **Kubernetes**.

JSONPatch defines a JSON Patch.

- Type: `object`

## Properties

### `expression`

- Required: false
- Type: `string`

expression will be evaluated by CEL to create a [JSON patch](https://jsonpatch.com/). ref: https://github.com/google/cel-spec

expression must return an array of JSONPatch values.

For example, this CEL expression returns a JSON patch to conditionally modify a value:

	  [
	    JSONPatch{op: "test", path: "/spec/example", value: "Red"},
	    JSONPatch{op: "replace", path: "/spec/example", value: "Green"}
	  ]

To define an object for the patch value, use Object types. For example:

	  [
	    JSONPatch{
	      op: "add",
	      path: "/spec/selector",
	      value: Object.spec.selector{matchLabels: {"environment": "test"}}
	    }
	  ]

To use strings containing '/' and '~' as JSONPatch path keys, use "jsonpatch.escapeKey". For example:

	  [
	    JSONPatch{
	      op: "add",
	      path: "/metadata/labels/" + jsonpatch.escapeKey("example.com/environment"),
	      value: "test"
	    },
	  ]

CEL expressions have access to the types needed to create JSON patches and objects:

- 'JSONPatch' - CEL type of JSON Patch operations. JSONPatch has the fields 'op', 'from', 'path' and 'value'.
  See [JSON patch](https://jsonpatch.com/) for more details. The 'value' field may be set to any of: string,
  integer, array, map or object.  If set, the 'path' and 'from' fields must be set to a
  [JSON pointer](https://datatracker.ietf.org/doc/html/rfc6901/) string, where the 'jsonpatch.escapeKey()' CEL
  function may be used to escape path keys containing '/' and '~'.
- 'Object' - CEL type of the resource object. - 'Object.<fieldName>' - CEL type of object field (such as 'Object.spec') - 'Object.<fieldName1>.<fieldName2>...<fieldNameN>` - CEL type of nested field (such as 'Object.spec.containers')

CEL expressions have access to the contents of the API request, organized into CEL variables as well as some other useful variables:

- 'object' - The object from the incoming request. The value is null for DELETE requests. - 'oldObject' - The existing object. The value is null for CREATE requests. - 'request' - Attributes of the API request([ref](/pkg/apis/admission/types.go#AdmissionRequest)). - 'params' - Parameter resource referred to by the policy binding being evaluated. Only populated if the policy has a ParamKind. - 'namespaceObject' - The namespace object that the incoming object belongs to. The value is null for cluster-scoped resources. - 'variables' - Map of composited variables, from its name to its lazily evaluated value.
  For example, a variable named 'foo' can be accessed as 'variables.foo'.
- 'authorizer' - A CEL Authorizer. May be used to perform authorization checks for the principal (user or service account) of the request.
  See https://pkg.go.dev/k8s.io/apiserver/pkg/cel/library#Authz
- 'authorizer.requestResource' - A CEL ResourceCheck constructed from the 'authorizer' and configured with the
  request resource.

CEL expressions have access to [Kubernetes CEL function libraries](https://kubernetes.io/docs/reference/using-api/cel/#cel-options-language-features-and-libraries) as well as:

- 'jsonpatch.escapeKey' - Performs JSONPatch key escaping. '~' and  '/' are escaped as '~0' and `~1' respectively).

Only property names of the form `[a-zA-Z_.-/][a-zA-Z0-9_.-/]*` are accessible. Required.

## JSON Schema

```json
{"description":"JSONPatch defines a JSON Patch.","properties":{"expression":{"description":"expression will be evaluated by CEL to create a [JSON patch](https://jsonpatch.com/). ref: https://github.com/google/cel-spec\n\nexpression must return an array of JSONPatch values.\n\nFor example, this CEL expression returns a JSON patch to conditionally modify a value:\n\n\t  [\n\t    JSONPatch{op: \"test\", path: \"/spec/example\", value: \"Red\"},\n\t    JSONPatch{op: \"replace\", path: \"/spec/example\", value: \"Green\"}\n\t  ]\n\nTo define an object for the patch value, use Object types. For example:\n\n\t  [\n\t    JSONPatch{\n\t      op: \"add\",\n\t      path: \"/spec/selector\",\n\t      value: Object.spec.selector{matchLabels: {\"environment\": \"test\"}}\n\t    }\n\t  ]\n\nTo use strings containing '/' and '~' as JSONPatch path keys, use \"jsonpatch.escapeKey\". For example:\n\n\t  [\n\t    JSONPatch{\n\t      op: \"add\",\n\t      path: \"/metadata/labels/\" + jsonpatch.escapeKey(\"example.com/environment\"),\n\t      value: \"test\"\n\t    },\n\t  ]\n\nCEL expressions have access to the types needed to create JSON patches and objects:\n\n- 'JSONPatch' - CEL type of JSON Patch operations. JSONPatch has the fields 'op', 'from', 'path' and 'value'.\n  See [JSON patch](https://jsonpatch.com/) for more details. The 'value' field may be set to any of: string,\n  integer, array, map or object.  If set, the 'path' and 'from' fields must be set to a\n  [JSON pointer](https://datatracker.ietf.org/doc/html/rfc6901/) string, where the 'jsonpatch.escapeKey()' CEL\n  function may be used to escape path keys containing '/' and '~'.\n- 'Object' - CEL type of the resource object. - 'Object.\u003cfieldName\u003e' - CEL type of object field (such as 'Object.spec') - 'Object.\u003cfieldName1\u003e.\u003cfieldName2\u003e...\u003cfieldNameN\u003e` - CEL type of nested field (such as 'Object.spec.containers')\n\nCEL expressions have access to the contents of the API request, organized into CEL variables as well as some other useful variables:\n\n- 'object' - The object from the incoming request. The value is null for DELETE requests. - 'oldObject' - The existing object. The value is null for CREATE requests. - 'request' - Attributes of the API request([ref](/pkg/apis/admission/types.go#AdmissionRequest)). - 'params' - Parameter resource referred to by the policy binding being evaluated. Only populated if the policy has a ParamKind. - 'namespaceObject' - The namespace object that the incoming object belongs to. The value is null for cluster-scoped resources. - 'variables' - Map of composited variables, from its name to its lazily evaluated value.\n  For example, a variable named 'foo' can be accessed as 'variables.foo'.\n- 'authorizer' - A CEL Authorizer. May be used to perform authorization checks for the principal (user or service account) of the request.\n  See https://pkg.go.dev/k8s.io/apiserver/pkg/cel/library#Authz\n- 'authorizer.requestResource' - A CEL ResourceCheck constructed from the 'authorizer' and configured with the\n  request resource.\n\nCEL expressions have access to [Kubernetes CEL function libraries](https://kubernetes.io/docs/reference/using-api/cel/#cel-options-language-features-and-libraries) as well as:\n\n- 'jsonpatch.escapeKey' - Performs JSONPatch key escaping. '~' and  '/' are escaped as '~0' and `~1' respectively).\n\nOnly property names of the form `[a-zA-Z_.-/][a-zA-Z0-9_.-/]*` are accessible. Required.","type":"string"}},"type":"object"}
```