# NestedStack

A CloudFormation nested stack.

When you apply template changes to update a top-level stack, CloudFormation
updates the top-level stack and initiates an update to its nested stacks.
CloudFormation updates the resources of modified nested stacks, but does not
update the resources of unmodified nested stacks.

Furthermore, this stack will not be treated as an independent deployment
artifact (won't be listed in "cdk list" or deployable through "cdk deploy"),
but rather only synthesized as a template and uploaded as an asset to S3.

Cross references of resource attributes between the parent stack and the
nested stack will automatically be translated to stack parameters and
outputs.

Extends: Construct › Stack › NestedStack
Implements: ITaggable, IConstruct, IDependable
Superclass of: KubectlProvider

- Source: [`core/lib/nested-stack.ts`](https://github.com/aws/aws-cdk/blob/v2.275.0/packages/aws-cdk-lib/core/lib/nested-stack.ts#L111)
- Type last changed: v2.207.0 · 24 Jul 2025

## Example

```ts
import * as cdk from 'aws-cdk-lib';
import { CustomResourceConfig } from 'aws-cdk-lib/custom-resources';
import * as s3deploy from 'aws-cdk-lib/aws-s3-deployment';

const app = new cdk.App();
const stack = new cdk.Stack(app, 'Stack');
CustomResourceConfig.of(app).addLogRetentionLifetime(logs.RetentionDays.TEN_YEARS);

const nestedStackA = new cdk.NestedStack(stack, 'NestedStackA');
let websiteBucketA = new s3.Bucket(nestedStackA, "WebsiteBucketA", {});
new s3deploy.BucketDeployment(nestedStackA, "s3deployA", {
    sources: [s3deploy.Source.jsonData("file.json", { a: "b" })],
    destinationBucket: websiteBucketA,
    logRetention: logs.RetentionDays.ONE_DAY, // overridden by the `TEN_YEARS` set by `CustomResourceConfig`.
});

const nestedStackB = new cdk.NestedStack(stack, 'NestedStackB');
let websiteBucketB = new s3.Bucket(nestedStackB, "WebsiteBucketB", {});
new s3deploy.BucketDeployment(nestedStackB, "s3deployB", {
    sources: [s3deploy.Source.jsonData("file.json", { a: "b" })],
    destinationBucket: websiteBucketB,
    logRetention: logs.RetentionDays.ONE_DAY, // overridden by the `TEN_YEARS` set by `CustomResourceConfig`.
});
```

## Initializer

```ts
new NestedStack(scope: Construct, id: string, props?: NestedStackProps)
```

## Construct Props

- `description`: string — A description of the stack.

  **Default:** No description.

- `notificationArns`: string[] — The Simple Notification Service (SNS) topics to publish stack related events.

  **Default:** notifications are not sent for this stack.

- `parameters`: { [key: string]: string } — The set value pairs that represent the parameters passed to CloudFormation when this nested stack is created.

  **Default:** no user-defined parameters are passed to the nested stack

  Each parameter has a name corresponding
  to a parameter defined in the embedded template and a value representing
  the value that you want to set for the parameter.

  The nested stack construct will automatically synthesize parameters in order
  to bind references from the parent stack(s) into the nested stack.

- `removalPolicy`: [RemovalPolicy](/cdk/api/v2/docs/aws-cdk-lib.RemovalPolicy.html) = RemovalPolicy.DESTROY — Policy to apply when the nested stack is removed.

  The default is `Destroy`, because all Removal Policies of resources inside the
  Nested Stack should already have been set correctly. You normally should
  not need to set this value.

- `suppressTemplateIndentation`: boolean — Enable this flag to suppress indentation in generated CloudFormation templates.

  **Default:** the value of `@aws-cdk/core:suppressTemplateIndentation`, or `false` if that is not set.

  If not specified, the value of the `@aws-cdk/core:suppressTemplateIndentation`
  context key will be used. If that is not specified, then the
  default value `false` will be used.

- `timeout`: [Duration](/cdk/api/v2/docs/aws-cdk-lib.Duration.html) — The length of time that CloudFormation waits for the nested stack to reach the CREATE_COMPLETE state.

  **Default:** no timeout

  When CloudFormation detects that the nested stack has reached the
  CREATE_COMPLETE state, it marks the nested stack resource as
  CREATE_COMPLETE in the parent stack and resumes creating the parent stack.
  If the timeout period expires before the nested stack reaches
  CREATE_COMPLETE, CloudFormation marks the nested stack as failed and rolls
  back both the nested stack and parent stack.

## Properties

- `account`: string — The AWS account into which this stack will be deployed.

  This value is resolved according to the following rules:

  1. The value provided to `env.account` when the stack is defined. This can
     either be a concrete account (e.g. `585695031111`) or the
     `Aws.ACCOUNT_ID` token.
  3. `Aws.ACCOUNT_ID`, which represents the CloudFormation intrinsic reference
     `{ "Ref": "AWS::AccountId" }` encoded as a string token.

  Preferably, you should use the return value as an opaque string and not
  attempt to parse it to implement your logic. If you do, you must first
  check that it is a concrete value an not an unresolved token. If this
  value is an unresolved token (`Token.isUnresolved(stack.account)` returns
  `true`), this implies that the user wishes that this stack will synthesize
  into an **account-agnostic template**. In this case, your code should either
  fail (throw an error, emit a synth error using `Annotations.of(construct).addError()`) or
  implement some other account-agnostic behavior.

- `artifactId`: string — The ID of the cloud assembly artifact for this stack.

- `availabilityZones`: string[] — Returns the list of AZs that are available in the AWS environment (account/region) associated with this stack.

  If the stack is environment-agnostic (either account and/or region are
  tokens), this property will return an array with 2 tokens that will resolve
  at deploy-time to the first two availability zones returned from CloudFormation's
  `Fn::GetAZs` intrinsic function.

  If they are not available in the context, returns a set of dummy values and
  reports them as missing, and let the CLI resolve them by calling EC2
  `DescribeAvailabilityZones` on the target environment.

  To specify a different strategy for selecting availability zones override this method.

- `bundlingRequired`: boolean — Indicates whether the stack requires bundling or not.

- `dependencies`: [Stack](/cdk/api/v2/docs/aws-cdk-lib.Stack.html)[] — Return the stacks this stack depends on.

- `env`: [ResourceEnvironment](/cdk/api/v2/docs/aws-cdk-lib.interfaces.ResourceEnvironment.html) — The environment this Stack deploys to.

- `environment`: string — The environment coordinates in which this stack is deployed.

  In the form
  `aws://account/region`. Use `stack.account` and `stack.region` to obtain
  the specific values, no need to parse.

  You can use this value to determine if two stacks are targeting the same
  environment.

  If either `stack.account` or `stack.region` are not concrete values (e.g.
  `Aws.ACCOUNT_ID` or `Aws.REGION`) the special strings `unknown-account` and/or
  `unknown-region` will be used respectively to indicate this stack is
  region/account-agnostic.

- `nested`: boolean — Indicates if this is a nested stack, in which case `parentStack` will include a reference to its parent.

- `nestedStackParent`: [Stack](/cdk/api/v2/docs/aws-cdk-lib.Stack.html) — If this is a nested stack, returns its parent stack.

- `nestedStackResource`: [CfnResource](/cdk/api/v2/docs/aws-cdk-lib.CfnResource.html) — If this is a nested stack, this represents its `AWS::CloudFormation::Stack` resource.

  `undefined` for top-level (non-nested) stacks.

- `node`: [Node](/cdk/api/v2/docs/constructs.Node.html) — The tree node.

- `notificationArns`: string[] — Returns the list of notification Amazon Resource Names (ARNs) for the current stack.

- `partition`: string — The partition in which this stack is defined.

- `region`: string — The AWS region into which this stack will be deployed (e.g. `us-west-2`).

  This value is resolved according to the following rules:

  1. The value provided to `env.region` when the stack is defined. This can
     either be a concrete region (e.g. `us-west-2`) or the `Aws.REGION`
     token.
  3. `Aws.REGION`, which is represents the CloudFormation intrinsic reference
     `{ "Ref": "AWS::Region" }` encoded as a string token.

  Preferably, you should use the return value as an opaque string and not
  attempt to parse it to implement your logic. If you do, you must first
  check that it is a concrete value an not an unresolved token. If this
  value is an unresolved token (`Token.isUnresolved(stack.region)` returns
  `true`), this implies that the user wishes that this stack will synthesize
  into a **region-agnostic template**. In this case, your code should either
  fail (throw an error, emit a synth error using `Annotations.of(construct).addError()`) or
  implement some other region-agnostic behavior.

- `stackId`: string — An attribute that represents the ID of the stack.

  This is a context aware attribute:
  - If this is referenced from the parent stack, it will return `{ "Ref": "LogicalIdOfNestedStackResource" }`.
  - If this is referenced from the context of the nested stack, it will return `{ "Ref": "AWS::StackId" }`

  Example value: `arn:aws:cloudformation:us-east-2:123456789012:stack/mystack-mynestedstack-sggfrhxhum7w/f449b250-b969-11e0-a185-5081d0136786`

- `stackName`: string — An attribute that represents the name of the nested stack.

  This is a context aware attribute:
  - If this is referenced from the parent stack, it will return a token that parses the name from the stack ID.
  - If this is referenced from the context of the nested stack, it will return `{ "Ref": "AWS::StackName" }`

  Example value: `mystack-mynestedstack-sggfrhxhum7w`

- `synthesizer`: [IStackSynthesizer](/cdk/api/v2/docs/aws-cdk-lib.IStackSynthesizer.html) — Synthesis method for this stack.

- `tags`: [TagManager](/cdk/api/v2/docs/aws-cdk-lib.TagManager.html) — Tags to be applied to the stack.

- `templateFile`: string — The name of the CloudFormation template file emitted to the output directory during synthesis.

  Example value: `MyStack.template.json`

- `templateOptions`: [ITemplateOptions](/cdk/api/v2/docs/aws-cdk-lib.ITemplateOptions.html) — Options for CloudFormation template (like version, transform, description).

- `terminationProtection`: boolean — Whether termination protection is enabled for this stack.

- `urlSuffix`: string — The Amazon domain suffix for the region in which this stack is defined.

## Methods

- `addDependency(target: Stack, reason?: string): void` — Use `addStackDependency` instead.

  This can be used to define dependencies between any two stacks within an
  app, and also supports nested stacks.

  Stack dependencies may not cross Stage boundaries.

  This method has been renamed to `addStackDependency` to more clearly
  set it apart from `construct.node.addDependency`. See the documentation
  of that function for more details.

- `addMetadata(key: string, value: any): void` — Adds an arbitrary key-value pair, with information you want to record about the stack.

  These get translated to the Metadata section of the generated template.

- `addStackDependency(target: Stack, reason?: string): void` — Add a dependency between this stack and another stack.

  This can be used to define dependencies between any two stacks within an
  app, and also supports nested stacks.

  Stack dependencies may not cross Stage boundaries.

  This method only adds dependencies between stacks. If you are looking
  for a generic construct-to-construct dependency mechanism, use
  `construct.node.addDependency` instead.

- `addStackTag(tagName: string, tagValue: string): void` — Configure a stack tag.

  At deploy time, CloudFormation will automatically apply all stack tags to all resources in the stack.

- `addTransform(transform: string): void` — Add a Transform to this stack. A Transform is a macro that AWS CloudFormation uses to process your template.

  Duplicate values are removed when stack is synthesized.

  **Parameters**

  - `transform` — The transform to add.

  ```ts
  declare const stack: Stack;

  stack.addTransform('AWS::Serverless-2016-10-31')
  ```

- `consumeListReference(value: string[], strength?: ReferenceStrength): string[]` (static) — Override the reference strength for a specific cross-stack string list reference.

  This is the string list equivalent of `consumeReference`.

  **Parameters**

  - `value` — A tokenized string list reference.
  - `strength` — The reference strength to use.

  **Returns:** A token that resolves to the same value but uses the overridden strength.

- `consumeReference(value: string, strength?: ReferenceStrength): string` (static) — Override the reference strength for a specific cross-stack reference value.

  Use this to weaken (or strengthen) an individual reference without
  affecting other references to the same resource. For example:

  ```ts
  // producerStack defines an SNS topic
  declare const topic: sns.Topic;

  // consumerStack subscribes to it with a weak reference,
  // so the producer can be torn down without blocking on this consumer
  const consumerStack = new Stack(app, 'Consumer', {
    env: { account: '123456789012', region: 'us-east-1' },
  });
  new sns.Subscription(consumerStack, 'Subscription', {
    topic: sns.Topic.fromTopicArn(consumerStack, 'Topic', Stack.consumeReference(topic.topicArn)),
    endpoint: 'https://example.com/webhook',
    protocol: sns.SubscriptionProtocol.HTTPS,
  });
  ```

  **Parameters**

  - `value` — A tokenized string reference (e.g. `bucket.bucketArn`).
  - `strength` — The reference strength to use.

  **Returns:** A token that resolves to the same value but uses the overridden strength.

- `exportStringListValue(exportedValue: any, options?: ExportValueOptions): string[]` — Create a CloudFormation Export for a string list value.

  Returns a string list representing the corresponding `Fn.importValue()`
  expression for this Export. The export expression is automatically wrapped with an
  `Fn::Join` and the import value with an `Fn::Split`, since CloudFormation can only
  export strings. You can control the name for the export by passing the `name` option.

  If you don't supply a value for `name`, the value you're exporting must be
  a Resource attribute (for example: `bucket.bucketName`) and it will be
  given the same name as the automatic cross-stack reference that would be created
  if you used the attribute in another Stack.

  One of the uses for this method is to *remove* the relationship between
  two Stacks established by automatic cross-stack references. It will
  temporarily ensure that the CloudFormation Export still exists while you
  remove the reference from the consuming stack. After that, you can remove
  the resource and the manual export.

  See `exportValue` for an example of this process.

- `exportValue(exportedValue: any, options?: ExportValueOptions): string` — Create a CloudFormation Export for a string value.

  Returns a string representing the corresponding `Fn.importValue()`
  expression for this Export. You can control the name for the export by
  passing the `name` option.

  If you don't supply a value for `name`, the value you're exporting must be
  a Resource attribute (for example: `bucket.bucketName`) and it will be
  given the same name as the automatic cross-stack reference that would be created
  if you used the attribute in another Stack.

  One of the uses for this method is to *remove* the relationship between
  two Stacks established by automatic cross-stack references. It will
  temporarily ensure that the CloudFormation Export still exists while you
  remove the reference from the consuming stack. After that, you can remove
  the resource and the manual export.

  Here is how the process works. Let's say there are two stacks,
  `producerStack` and `consumerStack`, and `producerStack` has a bucket
  called `bucket`, which is referenced by `consumerStack` (perhaps because
  an AWS Lambda Function writes into it, or something like that).

  It is not safe to remove `producerStack.bucket` because as the bucket is being
  deleted, `consumerStack` might still be using it.

  Instead, the process takes two deployments:

  **Deployment 1: break the relationship**:

  - Make sure `consumerStack` no longer references `bucket.bucketName` (maybe the consumer
    stack now uses its own bucket, or it writes to an AWS DynamoDB table, or maybe you just
    remove the Lambda Function altogether).
  - In the `ProducerStack` class, call `this.exportValue(this.bucket.bucketName)`. This
    will make sure the CloudFormation Export continues to exist while the relationship
    between the two stacks is being broken.
  - Deploy (this will effectively only change the `consumerStack`, but it's safe to deploy both).

  **Deployment 2: remove the bucket resource**:

  - You are now free to remove the `bucket` resource from `producerStack`.
  - Don't forget to remove the `exportValue()` call as well.
  - Deploy again (this time only the `producerStack` will be changed -- the bucket will be deleted).

- `formatArn(components: ArnComponents): string` — Creates an ARN from components.

  If `partition`, `region` or `account` are not specified, the stack's
  partition, region and account will be used.

  If any component is the empty string, an empty string will be inserted
  into the generated ARN at the location that component corresponds to.

  The ARN will be formatted as follows:

    arn:{partition}:{service}:{region}:{account}:{resource}{sep}{resource-name}

  The required ARN pieces that are omitted will be taken from the stack that
  the 'scope' is attached to. If all ARN pieces are supplied, the supplied scope
  can be 'undefined'.

- `getLogicalId(element: CfnElement): string` — Allocates a stack-unique CloudFormation-compatible logical identity for a specific resource.

  This method is called when a `CfnElement` is created and used to render the
  initial logical identity of resources. Logical ID renames are applied at
  this stage.

  This method uses the protected method `allocateLogicalId` to render the
  logical ID for an element. To modify the naming scheme, extend the `Stack`
  class and override this method.

  **Parameters**

  - `element` — The CloudFormation element for which a logical identity is needed.

- `isConstruct(x: any): boolean` (static) — Checks if `x` is a construct.

  Use this method instead of `instanceof` to properly detect `Construct`
  instances, even when the construct library is symlinked.

  Explanation: in JavaScript, multiple copies of the `constructs` library on
  disk are seen as independent, completely different libraries. As a
  consequence, the class `Construct` in each copy of the `constructs` library
  is seen as a different class, and an instance of one class will not test as
  `instanceof` the other class. `npm install` will not create installations
  like this, but users may manually symlink construct libraries together or
  use a monorepo tool: in those cases, multiple copies of the `constructs`
  library can be accidentally installed, and `instanceof` will behave
  unpredictably. It is safest to avoid using `instanceof`, and using
  this type-testing method instead.

  **Parameters**

  - `x` — Any object.

  **Returns:** true if `x` is an object created from a class which extends `Construct`.

- `isNestedStack(x: any): boolean` (static) — Checks if `x` is an object of type `NestedStack`.

- `isStack(x: any): boolean` (static) — Return whether the given object is a Stack.

  We do attribute detection since we can't reliably use 'instanceof'.

- `of(construct: IConstruct): Stack` (static) — Looks up the first stack scope in which `construct` is defined.

  Fails if there is no stack up the tree.

  Will return the closest containing `Stack` or `NestedStack`.

  **Parameters**

  - `construct` — The construct to start the search from.

- `regionalFact(factName: string, defaultValue?: string): string` — Look up a fact value for the given fact for the region of this stack.

  Will return a definite value only if the region of the current stack is resolved.
  If not, a lookup map will be added to the stack and the lookup will be done at
  CDK deployment time.

  What regions will be included in the lookup map is controlled by the
  `@aws-cdk/core:target-partitions` context value: it must be set to a list
  of partitions, and only regions from the given partitions will be included.
  If no such context key is set, all regions will be included.

  This function is intended to be used by construct library authors. Application
  builders can rely on the abstractions offered by construct libraries and do
  not have to worry about regional facts.

  If `defaultValue` is not given, it is an error if the fact is unknown for
  the given region.

- `removeStackTag(tagName: string): void` — Remove a stack tag.

  At deploy time, CloudFormation will automatically apply all stack tags to all resources in the stack.

- `renameLogicalId(oldId: string, newId: string): void` — Rename a generated logical identities.

  To modify the naming scheme strategy, extend the `Stack` class and
  override the `allocateLogicalId` method.

- `reportMissingContextKey(report: MissingContext): void` — Indicate that a context key was expected.

  Contains instructions which will be emitted into the cloud assembly on how
  the key should be supplied.

  **Parameters**

  - `report` — The set of parameters needed to obtain the context.

- `resolve(obj: any): any` — Resolve a tokenized value in the context of the current stack.

- `setParameter(name: string, value: string): void` — Assign a value to one of the nested stack parameters.

  **Parameters**

  - `name` — The parameter name (ID).
  - `value` — The value to assign.

- `splitArn(arn: string, arnFormat: ArnFormat): ArnComponents` — Splits the provided ARN into its components.

  Works both if 'arn' is a string like 'arn:aws:s3:::bucket',
  and a Token representing a dynamic CloudFormation expression
  (in which case the returned components will also be dynamic CloudFormation expressions,
  encoded as Tokens).

  **Parameters**

  - `arn` — the ARN to split into its components.
  - `arnFormat` — the expected format of 'arn' - depends on what format the service 'arn' represents uses.

- `toJsonString(obj: any, space?: number): string` — Convert an object, potentially containing tokens, to a JSON string.

- `toString(): string` — Returns a string representation of this construct.

- `toYamlString(obj: any): string` — Convert an object, potentially containing tokens, to a YAML string.

- `with(...mixins: IMixin[]): IConstruct` — Applies one or more mixins to this construct.

  Mixins are applied in order. The list of constructs is captured at the
  start of the call, so constructs added by a mixin will not be visited.
  Use multiple `with()` calls if subsequent mixins should apply to added
  constructs.