aws-cdk

What is aws-cdk?

The AWS Cloud Development Kit (AWS CDK) is an open-source software development framework to define cloud infrastructure in code and provision it through AWS CloudFormation. It provides high-level components called constructs that preconfigure cloud resources with proven defaults, so you can build cloud applications without needing to be an expert in AWS services.

What are aws-cdk's main functionalities?

Defining Infrastructure

This feature allows you to define AWS infrastructure using familiar programming languages. The code sample demonstrates how to define a new VPC using the AWS CDK.

const vpc = new ec2.Vpc(this, 'VPC');

Creating a Lambda Function

With AWS CDK, you can create serverless functions such as AWS Lambda. The code sample shows how to define a Lambda function with the Node.js 12.x runtime.

const lambdaFunction = new lambda.Function(this, 'MyFunction', {
  runtime: lambda.Runtime.NODEJS_12_X,
  handler: 'index.handler',
  code: lambda.Code.fromAsset('lambda')
});

Hosting a Static Website

AWS CDK can be used to host static websites on Amazon S3. The code sample illustrates how to create an S3 bucket configured for website hosting and how to deploy website content to it.

const bucket = new s3.Bucket(this, 'WebsiteBucket', {
  websiteIndexDocument: 'index.html'
});
new s3deploy.BucketDeployment(this, 'DeployWebsite', {
  sources: [s3deploy.Source.asset('./website-dist')],
  destinationBucket: bucket
});

Setting up an API Gateway

This feature enables the creation of Amazon API Gateway endpoints. The code sample shows how to set up a REST API with a GET method integrated with a Lambda function.

const api = new apigateway.RestApi(this, 'MyApi', {
  restApiName: 'Service'
});
const getLambdaIntegration = new apigateway.LambdaIntegration(getLambda);
api.root.addMethod('GET', getLambdaIntegration);

Other packages similar to aws-cdk

serverless

The Serverless Framework is similar to AWS CDK in that it allows you to define and deploy cloud infrastructure using code. It supports multiple cloud providers and is focused on building serverless applications. It uses a configuration file approach rather than an object-oriented programming model.

terraform

Terraform by HashiCorp is an infrastructure as code tool that allows you to define both cloud and on-premises resources with a declarative configuration language. It is cloud-agnostic and supports multiple providers, whereas AWS CDK is focused on AWS services.

pulumi

Pulumi is an infrastructure as code tool that allows you to define infrastructure using general-purpose programming languages. Similar to AWS CDK, Pulumi provides an object-oriented approach but supports multiple cloud providers, not just AWS.

README

AWS CDK Toolkit

---

---

The AWS CDK Toolkit provides the cdk command-line interface that can be used to work with AWS CDK applications.

Command	Description
cdk docs	Access the online documentation
cdk init	Start a new CDK project (app or library)
cdk list	List stacks and their dependencies in an application
cdk synth	Synthesize a CDK app to CloudFormation template(s)
cdk diff	Diff stacks against current state
cdk deploy	Deploy a stack into an AWS account
cdk rollback	Roll back a failed deployment
cdk import	Import existing AWS resources into a CDK stack
cdk migrate	Migrate AWS resources, CloudFormation stacks, and CloudFormation templates to CDK
cdk watch	Watches a CDK app for deployable and hotswappable changes
cdk destroy	Deletes a stack from an AWS account
cdk bootstrap	Deploy a toolkit stack to support deploying large stacks & artifacts
cdk gc	Garbage collect assets associated with the bootstrapped stack
cdk doctor	Inspect the environment and produce information useful for troubleshooting
cdk acknowledge	Acknowledge (and hide) a notice by issue number
cdk notices	List all relevant notices for the application

• Bundling
• MFA Support
• SSO Support
• Configuration
  • Running in CI

This module is part of the AWS Cloud Development Kit project.

Commands

cdk docs

Outputs the URL to the documentation for the current toolkit version, and attempts to open a browser to that URL.

$ # Open the documentation in the default browser (using 'open')
$ cdk docs
https://docs.aws.amazon.com/cdk/api/latest/

$ # Open the documentation in Chrome.
$ cdk docs --browser='chrome %u'
https://docs.aws.amazon.com/cdk/api/latest/

cdk init

Creates a new CDK project.

$ # List the available template types & languages
$ cdk init --list
Available templates:
* app: Template for a CDK Application
   └─ cdk init app --language=[csharp|fsharp|java|javascript|python|typescript]
* lib: Template for a CDK Construct Library
   └─ cdk init lib --language=typescript
* sample-app: Example CDK Application with some constructs
   └─ cdk init sample-app --language=[csharp|fsharp|java|javascript|python|typescript]

$ # Create a new library application in typescript
$ cdk init lib --language=typescript

cdk list

Lists the stacks and their dependencies modeled in the CDK app.

$ # List all stacks in the CDK app 'node bin/main.js'
$ cdk list --app='node bin/main.js'
Foo
Bar
Baz

$ # List all stack including all details (add --json to output JSON instead of YAML)
$ cdk list --app='node bin/main.js' --long
-
    name: Foo
    environment:
        name: 000000000000/bermuda-triangle-1
        account: '000000000000'
        region: bermuda-triangle-1
-
    name: Bar
    environment:
        name: 111111111111/bermuda-triangle-2
        account: '111111111111'
        region: bermuda-triangle-2
-
    name: Baz
    environment:
        name: 333333333333/bermuda-triangle-3
        account: '333333333333'
        region: bermuda-triangle-3

cdk synthesize

Synthesizes the CDK app and produces a cloud assembly to a designated output (defaults to cdk.out)

Typically you don't interact directly with cloud assemblies. They are files that include everything needed to deploy your app to a cloud environment. For example, it includes an AWS CloudFormation template for each stack in your app, and a copy of any file assets or Docker images that you reference in your app.

If your app contains a single stack or a stack is supplied as an argument to cdk synth, the CloudFormation template will also be displayed in the standard output (STDOUT) as YAML.

If there are multiple stacks in your application, cdk synth will synthesize the cloud assembly to cdk.out.

$ # Synthesize cloud assembly for StackName and output the CloudFormation template to STDOUT
$ cdk synth MyStackName

$ # Synthesize cloud assembly for all the stacks and save them into cdk.out/
$ cdk synth

$ # Synthesize cloud assembly for StackName, but don't include dependencies
$ cdk synth MyStackName --exclusively

$ # Synthesize cloud assembly for StackName, but don't write CloudFormation template output to STDOUT
$ cdk synth MyStackName --quiet

The quiet option can be set in the cdk.json file.

{
  "quiet": true
}

See the AWS Documentation to learn more about cloud assemblies. See the CDK reference documentation for details on the cloud assembly specification

cdk diff

Computes differences between the infrastructure specified in the current state of the CDK app and the currently deployed application (or a user-specified CloudFormation template). If you need the command to return a non-zero if any differences are found you need to use the --fail command line option.

$ # Diff against the currently deployed stack
$ cdk diff --app='node bin/main.js' MyStackName

$ # Diff against a specific template document
$ cdk diff --app='node bin/main.js' MyStackName --template=path/to/template.yml

The quiet flag can also be passed to the cdk diff command. Assuming there are no differences detected the output to the console will not contain strings such as the Stack MyStackName and There were no differences.

$ # Diff against the currently deployed stack with quiet parameter enabled
$ cdk diff --quiet --app='node bin/main.js' MyStackName

Note that the CDK::Metadata resource and the CheckBootstrapVersion Rule are excluded from cdk diff by default. You can force cdk diff to display them by passing the --strict flag.

The change-set flag will make diff create a change set and extract resource replacement data from it. This is a bit slower, but will provide no false positives for resource replacement. The --no-change-set mode will consider any change to a property that requires replacement to be a resource replacement, even if the change is purely cosmetic (like replacing a resource reference with a hardcoded arn).

cdk deploy

Deploys a stack of your CDK app to its environment. During the deployment, the toolkit will output progress indications, similar to what can be observed in the AWS CloudFormation Console. If the environment was never bootstrapped (using cdk bootstrap), only stacks that are not using assets and synthesize to a template that is under 51,200 bytes will successfully deploy.

$ cdk deploy --app='node bin/main.js' MyStackName

Before creating a change set, cdk deploy will compare the template and tags of the currently deployed stack to the template and tags that are about to be deployed and will skip deployment if they are identical. Use --force to override this behavior and always deploy the stack.

Disabling Rollback

If a resource fails to be created or updated, the deployment will roll back before the CLI returns. All changes made up to that point will be undone (resources that were created will be deleted, updates that were made will be changed back) in order to leave the stack in a consistent state at the end of the operation. If you are using the CDK CLI to iterate on a development stack in your personal account, you might not require CloudFormation to leave your stack in a consistent state, but instead would prefer to update your CDK application and try again.

To disable the rollback feature, specify --no-rollback (-R for short):

$ cdk deploy --no-rollback
$ cdk deploy -R

If a deployment fails you can update your code and immediately retry the deployment from the point of failure. If you would like to explicitly roll back a failed, paused deployment, use cdk rollback.

--no-rollback deployments cannot contain resource replacements. If the CLI detects that a resource is being replaced, it will prompt you to perform a regular replacement instead. If the stack rollback is currently paused and you are trying to perform an deployment that contains a replacement, you will be prompted to roll back first.

Deploying multiple stacks

You can have multiple stacks in a cdk app. An example can be found in how to create multiple stacks.

In order to deploy them, you can list the stacks you want to deploy. If your application contains pipeline stacks, the cdk list command will show stack names as paths, showing where they are in the pipeline hierarchy (e.g., PipelineStack, PipelineStack/Prod, PipelineStack/Prod/MyService etc).

If you want to deploy all of them, you can use the flag --all or the wildcard * to deploy all stacks in an app. Please note that, if you have a hierarchy of stacks as described above, --all and * will only match the stacks on the top level. If you want to match all the stacks in the hierarchy, use **. You can also combine these patterns. For example, if you want to deploy all stacks in the Prod stage, you can use cdk deploy PipelineStack/Prod/**.

--concurrency N allows deploying multiple stacks in parallel while respecting inter-stack dependencies to speed up deployments. It does not protect against CloudFormation and other AWS account rate limiting.

Parameters

Pass parameters to your template during deployment by using --parameters (STACK:KEY=VALUE). This will apply the value VALUE to the key KEY for stack STACK.

Example of providing an attribute value for an SNS Topic through a parameter in TypeScript:

Usage of parameter in CDK Stack:

new sns.Topic(this, 'TopicParameter', {
    topicName: new cdk.CfnParameter(this, 'TopicNameParam').value.toString()
});

Parameter values as a part of cdk deploy

$ cdk deploy --parameters "MyStackName:TopicNameParam=parameterized"

Parameter values can be overwritten by supplying the --force flag. Example of overwriting the topic name from a previous deployment.

$ cdk deploy --parameters "ParametersStack:TopicNameParam=blahagain" --force

⚠️ Parameters will be applied to all stacks if a stack name is not specified or * is provided. Parameters provided to Stacks that do not make use of the parameter will not successfully deploy.

⚠️ Parameters do not propagate to NestedStacks. These must be sent with the constructor. See Nested Stack documentation

Outputs

Write stack outputs from deployments into a file. When your stack finishes deploying, all stack outputs will be written to the output file as JSON.

Usage of output in a CDK stack

const fn = new lambda.Function(this, "fn", {
  handler: "index.handler",
  code: lambda.Code.fromInline(`exports.handler = \${handler.toString()}`),
  runtime: lambda.Runtime.NODEJS_LATEST
});

new cdk.CfnOutput(this, 'FunctionArn', {
  value: fn.functionArn,
});

Specify an outputs file to write to by supplying the --outputs-file parameter

$ cdk deploy --outputs-file outputs.json

Alternatively, the outputsFile key can be specified in the project config (cdk.json).

The following shows a sample cdk.json where the outputsFile key is set to outputs.json.

{
  "app": "npx ts-node bin/myproject.ts",
  "context": {
    "@aws-cdk/core:enableStackNameDuplicates": "true",
    "aws-cdk:enableDiffNoFail": "true",
    "@aws-cdk/core:stackRelativeExports": "true"
  },
  "outputsFile": "outputs.json"
}

The outputsFile key can also be specified as a user setting (~/.cdk.json)

When the stack finishes deployment, outputs.json would look like this:

{
  "MyStack": {
    "FunctionArn": "arn:aws:lambda:us-east-1:123456789012:function:MyStack-fn5FF616E3-G632ITHSP5HK"
  }
}

⚠️ The key of the outputs corresponds to the logical ID of the CfnOutput. Read more about identifiers in the CDK here

If multiple stacks are being deployed or the wild card * is used to deploy all stacks, all outputs are written to the same output file where each stack artifact ID is a key in the JSON file

$ cdk deploy '**' --outputs-file "/Users/code/myproject/outputs.json"

Example outputs.json after deployment of multiple stacks

{
  "MyStack": {
    "FunctionArn": "arn:aws:lambda:us-east-1:123456789012:function:MyStack-fn5FF616E3-G632ITHSP5HK"
  },
  "AnotherStack": {
    "VPCId": "vpc-z0mg270fee16693f"
  }
}

Deployment Progress

By default, stack deployment events are displayed as a progress bar with the events for the resource currently being deployed.

Set the --progress flag to request the complete history which includes all CloudFormation events

$ cdk deploy --progress events

Alternatively, the progress key can be specified in the project config (cdk.json).

The following shows a sample cdk.json where the progress key is set to events. When cdk deploy is executed, deployment events will include the complete history.

{
  "app": "npx ts-node bin/myproject.ts",
  "context": {
    "@aws-cdk/core:enableStackNameDuplicates": "true",
    "aws-cdk:enableDiffNoFail": "true",
    "@aws-cdk/core:stackRelativeExports": "true"
  },
  "progress": "events"
}

The progress key can also be specified as a user setting (~/.cdk.json)

CloudFormation Change Sets vs direct stack updates

By default, CDK creates a CloudFormation change set with the changes that will be deployed and then executes it. This behavior can be controlled with the --method parameter:

• --method=change-set (default): create and execute the change set.
• --method=prepare-change-set: create the change set but don't execute it. This is useful if you have external tools that will inspect the change set or you have an approval process for change sets.
• --method=direct: do not create a change set but apply the change immediately. This is typically a bit faster than creating a change set, but it loses the progress information.

To deploy faster without using change sets:

$ cdk deploy --method=direct

If a change set is created, it will be called cdk-deploy-change-set, and a previous change set with that name will be overwritten. The change set will always be created, even if it is empty. A name can also be given to the change set to make it easier to later execute:

$ cdk deploy --method=prepare-change-set --change-set-name MyChangeSetName

For more control over when stack changes are deployed, the CDK can generate a CloudFormation change set but not execute it.

Ignore No Stacks

You may have an app with multiple environments, e.g., dev and prod. When starting development, your prod app may not have any resources or the resources are commented out. In this scenario, you will receive an error message stating that the app has no stacks.

To bypass this error messages, you can pass the --ignore-no-stacks flag to the deploy command:

$ cdk deploy --ignore-no-stacks

Hotswap deployments for faster development

You can pass the --hotswap flag to the deploy command:

$ cdk deploy --hotswap [StackNames]

This will attempt to perform a faster, short-circuit deployment if possible (for example, if you changed the code of a Lambda function in your CDK app), skipping CloudFormation, and updating the affected resources directly; this includes changes to resources in nested stacks. If the tool detects that the change does not support hotswapping, it will ignore it and display that ignored change. To have hotswap fall back and perform a full CloudFormation deployment, exactly like cdk deploy does without the --hotswap flag, specify --hotswap-fallback, like so:

$ cdk deploy --hotswap-fallback [StackNames]

Passing either option to cdk deploy will make it use your current AWS credentials to perform the API calls - it will not assume the Roles from your bootstrap stack, even if the @aws-cdk/core:newStyleStackSynthesis feature flag is set to true (as those Roles do not have the necessary permissions to update AWS resources directly, without using CloudFormation). For that reason, make sure that your credentials are for the same AWS account that the Stack(s) you are performing the hotswap deployment for belong to, and that you have the necessary IAM permissions to update the resources that are being deployed.

Hotswapping is currently supported for the following changes (additional changes will be supported in the future):

• Code asset (including Docker image and inline code), tag changes, and configuration changes (only description and environment variables are supported) of AWS Lambda functions.
• AWS Lambda Versions and Aliases changes.
• Definition changes of AWS Step Functions State Machines.
• Container asset changes of AWS ECS Services.
• Website asset changes of AWS S3 Bucket Deployments.
• Source and Environment changes of AWS CodeBuild Projects.
• VTL mapping template changes for AppSync Resolvers and Functions.
• Schema changes for AppSync GraphQL Apis.

You can optionally configure the behavior of your hotswap deployments in cdk.json. Currently you can only configure ECS hotswap behavior:

{
"hotswap": {
    "ecs": {
      "minimumHealthyPercent": 100,
      "maximumHealthyPercent": 250
    }
  }
}

⚠ Note #1: This command deliberately introduces drift in CloudFormation stacks in order to speed up deployments. For this reason, only use it for development purposes. Never use this flag for your production deployments!

⚠ Note #2: This command is considered experimental, and might have breaking changes in the future.

⚠ Note #3: Expected defaults for certain parameters may be different with the hotswap parameter. For example, an ECS service's minimum healthy percentage will currently be set to 0. Please review the source accordingly if this occurs.

⚠ Note #4: Only usage of certain CloudFormation intrinsic functions are supported as part of a hotswapped deployment. At time of writing, these are:

• Ref
• Fn::GetAtt *
• Fn::ImportValue
• Fn::Join
• Fn::Select
• Fn::Split
• Fn::Sub

*: Fn::GetAtt is only partially supported. Refer to this implementation for supported resources and attributes.

cdk rollback

If a deployment performed using cdk deploy --no-rollback fails, your deployment will be left in a failed, paused state. From this state you can update your code and try the deployment again, or roll the deployment back to the last stable state.

To roll the deployment back, use cdk rollback. This will initiate a rollback to the last stable state of your stack.

Some resources may fail to roll back. If they do, you can try again by calling cdk rollback --orphan <LogicalId> (can be specified multiple times). Or, run cdk rollback --force to have the CDK CLI automatically orphan all failing resources.

(cdk rollback requires version 23 of the bootstrap stack, since it depends on new permissions necessary to call the appropriate CloudFormation APIs)

cdk watch

The watch command is similar to deploy, but instead of being a one-shot operation, the command continuously monitors the files of the project, and triggers a deployment whenever it detects any changes:

$ cdk watch DevelopmentStack
Detected change to 'lambda-code/index.js' (type: change). Triggering 'cdk deploy'
DevelopmentStack: deploying...

 ✅  DevelopmentStack

^C

To end a cdk watch session, interrupt the process by pressing Ctrl+C.

What files are observed is determined by the "watch" setting in your cdk.json file. It has two sub-keys, "include" and "exclude", each of which can be either a single string, or an array of strings. Each entry is interpreted as a path relative to the location of the cdk.json file. Globs, both * and **, are allowed to be used. Example:

{
  "app": "mvn -e -q compile exec:java",
  "watch": {
    "include": "src/main/**",
    "exclude": "target/*"
  }
}

The default for "include" is "**/*" (which means all files and directories in the root of the project), and "exclude" is optional (note that we always ignore files and directories starting with ., the CDK output directory, and the node_modules directory), so the minimal settings to enable watch are "watch": {}.

If either your CDK code, or application code, needs a build step before being deployed, watch works with the "build" key in the cdk.json file, for example:

{
  "app": "mvn -e -q exec:java",
  "build": "mvn package",
  "watch": {
    "include": "src/main/**",
    "exclude": "target/*"
  }
}

Note that watch by default uses hotswap deployments (see above for details) -- to turn them off, pass the --no-hotswap option when invoking it.

By default watch will also monitor all CloudWatch Log Groups in your application and stream the log events locally to your terminal. To disable this feature you can pass the --no-logs option when invoking it:

$ cdk watch --no-logs

You can increase the concurrency by which watch will deploy and hotswap your stacks by specifying --concurrency N. --concurrency for watch acts the same as --concurrency for deploy, in that it will deploy or hotswap your stacks while respecting inter-stack dependencies.

$ cdk watch --concurrency 5

Note: This command is considered experimental, and might have breaking changes in the future. The same limitations apply to to watch deployments as do to --hotswap deployments. See the Hotswap deployments for faster development section for more information.

cdk import

Sometimes you want to import AWS resources that were created using other means into a CDK stack. For some resources (like Roles, Lambda Functions, Event Rules, ...), it's feasible to create new versions in CDK and then delete the old versions. For other resources, this is not possible: stateful resources like S3 Buckets, DynamoDB tables, etc., cannot be easily deleted without impact on the service.

cdk import, which uses CloudFormation resource imports, makes it possible to bring an existing resource under CDK/CloudFormation's management. See the list of resources that can be imported here.

To import an existing resource to a CDK stack, follow the following steps:

1. Run a cdk diff to make sure there are no pending changes to the CDK stack you want to import resources into. The only changes allowed in an "import" operation are the addition of new resources which you want to import.
2. Add constructs for the resources you want to import to your Stack (for example, for an S3 bucket, add something like new s3.Bucket(this, 'ImportedS3Bucket', {});). Do not add any other changes! You must also make sure to exactly model the state that the resource currently has. For the example of the Bucket, be sure to include KMS keys, life cycle policies, and anything else that's relevant about the bucket. If you do not, subsequent update operations may not do what you expect.
3. Run the cdk import - if there are multiple stacks in the CDK app, pass a specific stack name as an argument.
4. The CLI will prompt you to pass in the actual names of the resources you are importing. After you supply it, the import starts.
5. When cdk import reports success, the resource is managed by CDK. Any subsequent changes in the construct configuration will be reflected on the resource.

Limitations

This feature currently has the following limitations:

• Importing resources into nested stacks is not possible.
• There is no check on whether the properties you specify are correct and complete for the imported resource. Try starting a drift detection operation after importing.
• Resources that depend on other resources must all be imported together, or one-by-one in the right order. If you do not, the CloudFormation deployment will fail with unresolved references.
• Uses the deploy role credentials (necessary to read the encrypted staging bucket). Requires version 12 of the bootstrap stack, for the added IAM permissions to the deploy-role.

cdk migrate

⚠️CAUTION⚠️: CDK Migrate is currently experimental and may have breaking changes in the future.

CDK Migrate generates a CDK app from deployed AWS resources using --from-scan, deployed AWS CloudFormation stacks using --from-stack, and local AWS CloudFormation templates using --from-path.

To learn more about the CDK Migrate feature, see Migrate to AWS CDK. For more information on cdk migrate command options, see cdk migrate command reference.

The new CDK app will be initialized in the current working directory and will include a single stack that is named with the value you provide using --stack-name. The new stack, app, and directory will all use this name. To specify a different output directory, use --output-path. You can create the new CDK app in any CDK supported programming language using --language.

Migrate from an AWS CloudFormation stack

Migrate from a deployed AWS CloudFormation stack in a specific AWS account and AWS Region using --from-stack. Provide --stack-name to identify the name of your stack. Account and Region information are retrieved from default CDK CLI sources. Use --account and --region options to provide other values. The following is an example that migrates myCloudFormationStack to a new CDK app using TypeScript:

$ cdk migrate --language typescript --from-stack --stack-name 'myCloudFormationStack'

Migrate from a local AWS CloudFormation template

Migrate from a local YAML or JSON AWS CloudFormation template using --from-path. Provide a name for the stack that will be created in your new CDK app using --stack-name. Account and Region information are retrieved from default CDK CLI sources. Use --account and --region options to provide other values. The following is an example that creates a new CDK app using TypeScript that includes a myCloudFormationStack stack from a local template.json file:

$ cdk migrate --language typescript --from-path "./template.json" --stack-name "myCloudFormationStack"

Migrate from deployed AWS resources

Migrate from deployed AWS resources in a specific AWS account and Region that are not associated with an AWS CloudFormation stack using --from-scan. These would be resources that were provisioned outside of an IaC tool. CDK Migrate utilizes the IaC generator service to scan for resources and generate a template. Then, the CDK CLI references the template to create a new CDK app. To learn more about IaC generator, see Generating templates for existing resources.

Account and Region information are retrieved from default CDK CLI sources. Use --account and --region options to provide other values. The following is an example that creates a new CDK app using TypeScript that includes a new myCloudFormationStack stack from deployed resources:

$ cdk migrate --language typescript --from-scan --stack-name "myCloudFormationStack"

Since CDK Migrate relies on the IaC generator service, any limitations of IaC generator will apply to CDK Migrate. For general limitations, see Considerations.

IaC generator limitations with discovering resource and property values will also apply here. As a result, CDK Migrate will only migrate resources supported by IaC generator. Some of your resources may not be supported and some property values may not be accessible. For more information, see Iac generator and write-only properties and Supported resource types.

You can specify filters using --filter to specify which resources to migrate. This is a good option to use if you are over the IaC generator total resource limit.

After migration, you must resolve any write-only properties that were detected by IaC generator from your deployed resources. To learn more, see Resolve write-only properties.

Examples

Generate a TypeScript CDK app from a local AWS CloudFormation template.json file

$ # template.json is a valid cloudformation template in the local directory
$ cdk migrate --stack-name MyAwesomeApplication --language typescript --from-path MyTemplate.json

This command generates a new directory named MyAwesomeApplication within your current working directory, and then initializes a new CDK application within that directory. The CDK app contains a MyAwesomeApplication stack with resources configured to match those in your local CloudFormation template.

This results in a CDK application with the following structure, where the lib directory contains a stack definition with the same resource configuration as the provided template.json.

├── README.md
├── bin
│   └── my_awesome_application.ts
├── cdk.json
├── jest.config.js
├── lib
│   └── my_awesome_application-stack.ts
├── package.json
├── tsconfig.json

Generate a Python CDK app from a deployed stack

If you already have a CloudFormation stack deployed in your account and would like to manage it with CDK, you can migrate the deployed stack to a new CDK app. The value provided with --stack-name must match the name of the deployed stack.

$ # generate a Python application from MyDeployedStack in your account
$ cdk migrate --stack-name MyDeployedStack --language python --from-stack

This will generate a Python CDK app which will synthesize the same configuration of resources as the deployed stack.

Generate a TypeScript CDK app from deployed AWS resources that are not associated with a stack

If you have resources in your account that were provisioned outside AWS IaC tools and would like to manage them with the CDK, you can use the --from-scan option to generate the application.

In this example, we use the --filter option to specify which resources to migrate. You can filter resources to limit the number of resources migrated to only those specified by the --filter option, including any resources they depend on, or resources that depend on them (for example A filter which specifies a single Lambda Function, will find that specific table and any alarms that may monitor it). The --filter argument offers both AND as well as OR filtering.

OR filtering can be specified by passing multiple --filter options, and AND filtering can be specified by passing a single --filter option with multiple comma separated key/value pairs as seen below (see below for examples). It is recommended to use the --filter option to limit the number of resources returned as some resource types provide sample resources by default in all accounts which can add to the resource limits.

--from-scan takes 3 potential arguments: --new, most-recent, and undefined. If --new is passed, CDK Migrate will initiate a new scan of the account and use that new scan to discover resources. If --most-recent is passed, CDK Migrate will use the most recent scan of the account to discover resources. If neither --new nor --most-recent are passed, CDK Migrate will take the most recent scan of the account to discover resources, unless there is no recent scan, in which case it will initiate a new scan.

# Filtering options
identifier|id|resource-identifier=<resource-specific-resource-identifier-value>
type|resource-type-prefix=<resource-type-prefix>
tag-key=<tag-key>
tag-value=<tag-value>

Additional examples of migrating from deployed resources

$ # Generate a typescript application from all un-managed resources in your account
$ cdk migrate --stack-name MyAwesomeApplication --language typescript --from-scan

$ # Generate a typescript application from all un-managed resources in your account with the tag key "Environment" AND the tag value "Production"
$ cdk migrate --stack-name MyAwesomeApplication --language typescript --from-scan --filter tag-key=Environment,tag-value=Production

$ # Generate a python application from any dynamoDB resources with the tag-key "dev" AND the tag-value "true" OR any SQS::Queue
$ cdk migrate --stack-name MyAwesomeApplication --language python --from-scan --filter type=AWS::DynamoDb::,tag-key=dev,tag-value=true --filter type=SQS::Queue

$ # Generate a typescript application from a specific lambda function by providing it's specific resource identifier
$ cdk migrate --stack-name MyAwesomeApplication --language typescript --from-scan --filter identifier=myAwesomeLambdaFunction

CDK Migrate Limitations

• CDK Migrate does not currently support nested stacks, custom resources, or the Fn::ForEach intrinsic function.

• CDK Migrate will only generate L1 constructs and does not currently support any higher level abstractions.

• CDK Migrate successfully generating an application does not guarantee the application is immediately deployable. It simply generates a CDK application which will synthesize a template that has identical resource configurations to the provided template.

  • CDK Migrate does not interact with the CloudFormation service to verify the template provided can deploy on its own. Although by default any CDK app generated using the --from-scan option exclude CloudFormation managed resources, CDK Migrate will not verify prior to deployment that any resources scanned, or in the provided template are already managed in other CloudFormation templates, nor will it verify that the resources in the provided template are available in the desired regions, which may impact ADC or Opt-In regions.

  • If the provided template has parameters without default values, those will need to be provided before deploying the generated application.

In practice this is how CDK Migrate generated applications will operate in the following scenarios:

Situation	Result
Provided template + stack-name is from a deployed stack in the account/region	The CDK application will deploy as a changeset to the existing stack
Provided template has no overlap with resources already in the account/region	The CDK application will deploy a new stack successfully
Provided template has overlap with Cloudformation managed resources already in the account/region	The CDK application will not be deployable unless those resources are removed
Provided template has overlap with un-managed resources already in the account/region	The CDK application will not be deployable until those resources are adopted with cdk import
No template has been provided and resources exist in the region the scan is done	The CDK application will be immediatly deployable and will import those resources into a new cloudformation stack upon deploy

The provided template is already deployed to CloudFormation in the account/region

If the provided template came directly from a deployed CloudFormation stack, and that stack has not experienced any drift, then the generated application will be immediately deployable, and will not cause any changes to the deployed resources. Drift might occur if a resource in your template was modified outside of CloudFormation, namely via the AWS Console or AWS CLI.

The provided template is not deployed to CloudFormation in the account/region, and there is not overlap with existing resources in the account/region

If the provided template represents a set of resources that have no overlap with resources already deployed in the account/region, then the generated application will be immediately deployable. This could be because the stack has never been deployed, or the application was generated from a stack deployed in another account/region.

In practice this means for any resource in the provided template, for example,

    "S3Bucket": {
      "Type": "AWS::S3::Bucket",
      "Properties": {
        "BucketName": "amzn-s3-demo-bucket",
        "AccessControl": "PublicRead",
      },
      "DeletionPolicy": "Retain"
    }

There must not exist a resource of that type with the same identifier in the desired region. In this example that identfier would be "amzn-s3-demo-bucket"

The provided template is not deployed to CloudFormation in the account/region, and there is overlap with existing resources in the account/region

If the provided template represents a set of resources that overlap with resources already deployed in the account/region, then the generated application will not be immediately deployable. If those overlapped resources are already managed by another CloudFormation stack in that account/region, then those resources will need to be manually removed from the provided template. Otherwise, if the overlapped resources are not managed by another CloudFormation stack, then first remove those resources from your CDK Application Stack, deploy the cdk application successfully, then re-add them and run cdk import to import them into your deployed stack.

cdk destroy

Deletes a stack from it's environment. This will cause the resources in the stack to be destroyed (unless they were configured with a DeletionPolicy of Retain). During the stack destruction, the command will output progress information similar to what cdk deploy provides.

$ cdk destroy --app='node bin/main.js' MyStackName

cdk bootstrap

Deploys a CDKToolkit CloudFormation stack into the specified environment(s), that provides an S3 bucket and ECR repository that cdk deploy will use to store synthesized templates and the related assets, before triggering a CloudFormation stack update. The name of the deployed stack can be configured using the --toolkit-stack-name argument. The S3 Bucket Public Access Block Configuration can be configured using the --public-access-block-configuration argument. ECR uses immutable tags for images.

$ # Deploys to all environments
$ cdk bootstrap --app='node bin/main.js'

$ # Deploys only to environments foo and bar
$ cdk bootstrap --app='node bin/main.js' foo bar

By default, bootstrap stack will be protected from stack termination. This can be disabled using --termination-protection argument.

If you have specific prerequisites not met by the example template, you can customize it to fit your requirements, by exporting the provided one to a file and either deploying it yourself using CloudFormation directly, or by telling the CLI to use a custom template. That looks as follows:

# Dump the built-in template to a file
$ cdk bootstrap --show-template > bootstrap-template.yaml

# Edit 'bootstrap-template.yaml' to your liking

# Tell CDK to use the customized template
$ cdk bootstrap --template bootstrap-template.yaml

Out of the box customization options are also available as arguments. To use a permissions boundary:

• --example-permissions-boundary indicates the example permissions boundary, supplied by CDK
• --custom-permissions-boundary specifies, by name a predefined, customer maintained, boundary

A few notes to add at this point. The CDK supplied permissions boundary policy should be regarded as an example. Edit the content and reference the example policy if you're testing out the feature, turn it into a new policy for actual deployments (if one does not already exist). The concern here is drift as, most likely, a permissions boundary is maintained and has dedicated conventions, naming included.

For more information on configuring permissions, including using permissions boundaries see the Security And Safety Dev Guide

Once a bootstrap template has been deployed with a set of parameters, you must use the --no-previous-parameters CLI flag to change any of these parameters on future deployments.

Note Please note that when you use this flag, you must resupply all previously supplied parameters.

For example if you bootstrap with a custom permissions boundary

cdk bootstrap --custom-permissions-boundary my-permissions-boundary

In order to remove that permissions boundary you have to specify the --no-previous-parameters option.

cdk bootstrap --no-previous-parameters

cdk gc

CDK Garbage Collection.

[!CAUTION] CDK Garbage Collection is under development and therefore must be opted in via the --unstable flag: cdk gc --unstable=gc. --unstable indicates that the scope and API of feature might still change. Otherwise the feature is generally production ready and fully supported.

cdk gc garbage collects unused assets from your bootstrap bucket via the following mechanism:

• for each object in the bootstrap S3 Bucket, check to see if it is referenced in any existing CloudFormation templates
• if not, it is treated as unused and gc will either tag it or delete it, depending on your configuration.

The high-level mechanism works identically for unused assets in bootstrapped ECR Repositories.

The most basic usage looks like this:

cdk gc --unstable=gc

This will garbage collect all unused assets in all environments of the existing CDK App.

To specify one type of asset, use the type option (options are all, s3, ecr):

cdk gc --unstable=gc --type=s3

Otherwise cdk gc defaults to collecting assets in both the bootstrapped S3 Bucket and ECR Repository.

cdk gc will garbage collect S3 and ECR assets from the current bootstrapped environment(s) and immediately delete them. Note that, since the default bootstrap S3 Bucket is versioned, object deletion will be handled by the lifecycle policy on the bucket.

Before we begin to delete your assets, you will be prompted:

cdk gc --unstable=gc

Found X objects to delete based off of the following criteria:
- objects have been isolated for > 0 days
- objects were created > 1 days ago

Delete this batch (yes/no/delete-all)?

Since it's quite possible that the bootstrap bucket has many objects, we work in batches of 1000 objects or 100 images. To skip the prompt either reply with delete-all, or use the --confirm=false option.

cdk gc --unstable=gc --confirm=false

If you are concerned about deleting assets too aggressively, there are multiple levers you can configure:

• rollback-buffer-days: this is the amount of days an asset has to be marked as isolated before it is elligible for deletion.
• created-buffer-days: this is the amount of days an asset must live before it is elligible for deletion.

When using rollback-buffer-days, instead of deleting unused objects, cdk gc will tag them with today's date instead. It will also check if any objects have been tagged by previous runs of cdk gc and delete them if they have been tagged for longer than the buffer days.

When using created-buffer-days, we simply filter out any assets that have not persisted that number of days.

cdk gc --unstable=gc --rollback-buffer-days=30 --created-buffer-days=1

You can also configure the scope that cdk gc performs via the --action option. By default, all actions are performed, but you can specify print, tag, or delete-tagged.

• print performs no changes to your AWS account, but finds and prints the number of unused assets.
• tag tags any newly unused assets, but does not delete any unused assets.
• delete-tagged deletes assets that have been tagged for longer than the buffer days, but does not tag newly unused assets.

cdk gc --unstable=gc --action=delete-tagged --rollback-buffer-days=30

This will delete assets that have been unused for >30 days, but will not tag additional assets.

Here is a diagram that shows the algorithm of garbage collection:

Theoretical Race Condition with REVIEW_IN_PROGRESS stacks

When gathering stack templates, we are currently ignoring REVIEW_IN_PROGRESS stacks as no template is available during the time the stack is in that state. However, stacks in REVIEW_IN_PROGRESS have already passed through the asset uploading step, where it either uploads new assets or ensures that the asset exists. Therefore it is possible the assets it references are marked as isolated and garbage collected before the stack template is available.

Our recommendation is to not deploy stacks and run garbage collection at the same time. If that is unavoidable, setting --created-buffer-days will help as garbage collection will avoid deleting assets that are recently created. Finally, if you do result in a failed deployment, the mitigation is to redeploy, as the asset upload step will be able to reupload the missing asset.

In practice, this race condition is only for a specific edge case and unlikely to happen but please open an issue if you think that this has happened to your stack.

cdk doctor

Inspect the current command-line environment and configurations, and collect information that can be useful for troubleshooting problems. It is usually a good idea to include the information provided by this command when submitting a bug report.

$ cdk doctor
ℹ️ CDK Version: 1.0.0 (build e64993a)
ℹ️ AWS environment variables:
  - AWS_EC2_METADATA_DISABLED = 1
  - AWS_SDK_LOAD_CONFIG = 1

Notices

CDK Notices are important messages regarding security vulnerabilities, regressions, and usage of unsupported versions. Relevant notices appear on every command by default. For example,

$ cdk deploy

... # Normal output of the command

NOTICES

22090   cli: cdk init produces EACCES: permission denied and does not fill the directory

        Overview: The CLI is unable to initialize new apps if CDK is
                  installed globally in a directory owned by root

        Affected versions: cli: 2.42.0.

        More information at: https://github.com/aws/aws-cdk/issues/22090


27547   Incorrect action in policy of Bucket `grantRead` method

        Overview: Using the `grantRead` method on `aws-cdk-lib/aws-s3.Bucket`
                  results in an invalid action attached to the resource policy
                  which can cause unexpected failures when interacting
                  with the bucket.

        Affected versions: aws-cdk-lib.aws_s3.Bucket: 2.101.0.

        More information at: https://github.com/aws/aws-cdk/issues/27547


If you don’t want to see a notice anymore, use "cdk acknowledge ID". For example, "cdk acknowledge 16603".

There are several types of notices you may encounter, differentiated by the affected component:

• cli: notifies you about issues related to your CLI version.
• framework: notifies you about issues related to your version of core constructs (e.g Stack).
• aws-cdk-lib.{module}.{construct}: notifies you about issue related to your version of a specific construct (e.g aws-cdk-lib.aws_s3.Bucket)
• bootstrap: notifies you about issues related to your version of the bootstrap stack. Note that these types of notices are only shown during the cdk deploy command.

You can suppress notices in a variety of ways:

• per individual execution:

  cdk deploy --no-notices

• disable all notices indefinitely through context in cdk.json:

  {
    "notices": false,
    "context": {
      ...
    }
  }
  

• acknowledging individual notices via cdk acknowledge (see below).

cdk acknowledge

To hide a particular notice that has been addressed or does not apply, call cdk acknowledge with the ID of the notice:

$cdk acknowledge 16603

Please note that the acknowledgements are made project by project. If you acknowledge an notice in one CDK project, it will still appear on other projects when you run any CDK commands, unless you have suppressed or disabled notices.

cdk notices

List the notices that are relevant to the current CDK repository, regardless of context flags or notices that have been acknowledged:

$ cdk notices

NOTICES

16603   Toggling off auto_delete_objects for Bucket empties the bucket

        Overview: if a stack is deployed with an S3 bucket with
                  auto_delete_objects=True, and then re-deployed with
                  auto_delete_objects=False, all the objects in the bucket
                  will be deleted.

        Affected versions: framework: <=2.15.0 >=2.10.0

        More information at: https://github.com/aws/aws-cdk/issues/16603


If you don’t want to see a notice anymore, use "cdk acknowledge <id>". For example, "cdk acknowledge 16603".

List the unacknowledged notices:

$ cdk notices --unacknowledged

NOTICES         (What's this? https://github.com/aws/aws-cdk/wiki/CLI-Notices)

29483	(cli): Upgrading to v2.132.0 or v2.132.1 breaks cdk diff functionality

	Overview: cdk diff functionality used to rely on assuming lookup-role.
	          With a recent change present in v2.132.0 and v2.132.1, it is
	          now trying to assume deploy-role with the lookup-role. This
	          leads to an authorization error if permissions were not
	          defined to assume deploy-role.

	Affected versions: cli: >=2.132.0 <=2.132.1

	More information at: https://github.com/aws/aws-cdk/issues/29483


If you don’t want to see a notice anymore, use "cdk acknowledge <id>". For example, "cdk acknowledge 29483".

There are 1 unacknowledged notice(s).

Bundling

By default asset bundling is skipped for cdk list and cdk destroy. For cdk deploy, cdk diff and cdk synthesize the default is to bundle assets for all stacks unless exclusively is specified. In this case, only the listed stacks will have their assets bundled.

MFA support

If mfa_serial is found in the active profile of the shared ini file AWS CDK will ask for token defined in the mfa_serial. This token will be provided to STS assume role call.

Example profile in ~/.aws/config where mfa_serial is used to assume role:

[profile my_assume_role_profile]
source_profile=my_source_role
role_arn=arn:aws:iam::123456789123:role/role_to_be_assumed
mfa_serial=arn:aws:iam::123456789123:mfa/my_user

SSO support

If you create an SSO profile with aws configure sso and run aws sso login, the CDK can use those credentials if you set the profile name as the value of AWS_PROFILE or pass it to --profile.

Configuration

On top of passing configuration through command-line arguments, it is possible to use JSON configuration files. The configuration's order of precedence is:

1. Command-line arguments
2. Project configuration (./cdk.json)
3. User configuration (~/.cdk.json)

JSON Configuration files

Some of the interesting keys that can be used in the JSON configuration files:

{
    "app": "node bin/main.js",                  // Command to start the CDK app      (--app='node bin/main.js')
    "build": "mvn package",                     // Specify pre-synth build           (--build='mvn package')
    "context": {                                // Context entries                   (--context=key=value)
        "key": "value"
    },
    "toolkitStackName": "foo",                  // Customize 'bootstrap' stack name  (--toolkit-stack-name=foo)
    "toolkitBucket": {
        "bucketName": "amzn-s3-demo-bucket",    // Customize 'bootstrap' bucket name (--toolkit-bucket-name=amzn-s3-demo-bucket)
        "kmsKeyId": "fooKMSKey"                 // Customize 'bootstrap' KMS key id  (--bootstrap-kms-key-id=fooKMSKey)
    },
    "versionReporting": false,                  // Opt-out of version reporting      (--no-version-reporting)
}

If specified, the command in the build key will be executed immediately before synthesis. This can be used to build Lambda Functions, CDK Application code, or other assets. build cannot be specified on the command line or in the User configuration, and must be specified in the Project configuration. The command specified in build will be executed by the "watch" process before deployment.

Environment

The following environment variables affect aws-cdk:

• CDK_DISABLE_VERSION_CHECK: If set, disable automatic check for newer versions.
• CDK_NEW_BOOTSTRAP: use the modern bootstrapping stack.

Running in CI

The CLI will attempt to detect whether it is being run in CI by looking for the presence of an environment variable CI=true. This can be forced by passing the --ci flag. By default the CLI sends most of its logs to stderr, but when ci=true it will send the logs to stdout instead.

Changing the default TypeScript transpiler

The ts-node package used to synthesize and deploy CDK apps supports an alternate transpiler that might improve transpile times. The SWC transpiler is written in Rust and has no type checking. The SWC transpiler should be enabled by experienced TypeScript developers.

To enable the SWC transpiler, install the package in the CDK app.

npm i -D @swc/core @swc/helpers regenerator-runtime

And, update the tsconfig.json file to add the ts-node property.

{
  "ts-node": {
    "swc": true
  }
}

The documentation may be found at https://typestrong.org/ts-node/docs/swc/