AWS CDK Toolkit (cdk command) - AWS Cloud Development Kit (AWS CDK) v2

This is the AWS CDK v2 Developer Guide. The older CDK v1 entered maintenance on June 1, 2022 and ended support on June 1, 2023.

AWS CDK Toolkit (cdk command)

The AWS CDK Toolkit, the CLI command cdk, is the primary tool for interacting with your AWS CDK app. It executes your app, interrogates the application model you defined, and produces and deploys the AWS CloudFormation templates generated by the AWS CDK. It also provides other features useful for creating and working with AWS CDK projects. This topic contains information about common use cases of the CDK Toolkit.

The AWS CDK Toolkit is installed with the Node Package Manager. In most cases, we recommend installing it globally.

npm install -g aws-cdk # install latest version npm install -g aws-cdk@X.YY.Z # install specific version

If you regularly work with multiple versions of the AWS CDK, consider installing a matching version of the AWS CDK Toolkit in individual CDK projects. To do this, omit -g from the npm install command. Then use npx aws-cdk to invoke it. This runs the local version if one exists, falling back to a global version if not.

Toolkit commands

All CDK Toolkit commands start with cdk, which is followed by a subcommand (list, synthesize, deploy, etc.). Some subcommands have a shorter version (ls, synth, etc.) that is equivalent. Options and arguments follow the subcommand in any order.

For a description of all subcommands, options, and arguments, see AWS CDK CLI command reference.

Specifying options and their values

Command line options begin with two hyphens (--). Some frequently used options have single-letter synonyms that begin with a single hyphen (for example, --app has a synonym -a). The order of options in an AWS CDK Toolkit command is not important.

All options accept a value, which must follow the option name. The value may be separated from the name by white space or by an equals sign =. The following two options are equivalent.

--toolkit-stack-name MyBootstrapStack --toolkit-stack-name=MyBootstrapStack

Some options are flags (Booleans). You may specify true or false as their value. If you do not provide a value, the value is taken to be true. You may also prefix the option name with no- to imply false.

# sets staging flag to true --staging --staging=true --staging true # sets staging flag to false --no-staging --staging=false --staging false

A few options, namely --context, --parameters, --plugin, --tags, and --trust, may be specified more than once to specify multiple values. These are noted as having [array] type in the CDK Toolkit help. For example:

cdk bootstrap --tags costCenter=0123 --tags responsibleParty=jdoe

Built-in help

The AWS CDK Toolkit has integrated help. You can see general help about the utility and a list of the provided subcommands by issuing:

cdk --help

To see help for a particular subcommand, for example deploy, specify it before the --help flag.

cdk deploy --help

Issue cdk version to display the version of the AWS CDK Toolkit. Provide this information when requesting support.

Version reporting

To gain insight into how the AWS CDK is used, the constructs used by AWS CDK applications are collected and reported by using a resource identified as AWS::CDK::Metadata. This resource is added to AWS CloudFormation templates, and can easily be reviewed. This information can also be used by AWS to identify stacks using a construct with known security or reliability issues. It can also be used to contact their users with important information.


Before version 1.93.0, the AWS CDK reported the names and versions of the modules loaded during synthesis, instead of the constructs used in the stack.

By default, the AWS CDK reports the use of constructs in the following NPM modules that are used in the stack:

  • AWS CDK core module

  • AWS Construct Library modules

  • AWS Solutions Constructs module

  • AWS Render Farm Deployment Kit module

The AWS::CDK::Metadata resource looks something like the following.

  Type: "AWS::CDK::Metadata"
    Analytics: "v2:deflate64:H4sIAND9SGAAAzXKSw5AMBAA0L1b2PdzBYnEAdio3RglglY60zQi7u6TWL/XKmNUlxeQSOKwaPTBqrNhwEWU3hGHiCzK0dWWfAxoL/Fd8mvk+QkS/0X6BdjnCdgmOOQKWz+AqqLDt2Y3YMnLYWwAAAA="

The Analytics property is a gzipped, base64-encoded, prefix-encoded list of the constructs in the stack.

To opt out of version reporting, use one of the following methods:

  • Use the cdk command with the --no-version-reporting argument to opt out for a single command.

    cdk --no-version-reporting synth

    Remember, the AWS CDK Toolkit synthesizes fresh templates before deploying, so you should also add --no-version-reporting to cdk deploy commands.

  • Set versionReporting to false in ./cdk.json or ~/.cdk.json. This opts out unless you opt in by specifying --version-reporting on an individual command.

    { "app": "...", "versionReporting": false }

Authentication with AWS

There are different ways in which you can configure programmatic access to AWS resources, depending on the environment and the AWS access available to you.

To choose your method of authentication and configure it for the CDK Toolkit, see Authentication and access in the AWS SDKs and Tools Reference Guide.

The recommended approach for new users developing locally, who are not given a method of authentication by their employer, is to set up AWS IAM Identity Center. This method includes installing the AWS CLI for ease of configuration and for regularly signing in to the AWS access portal. If you choose this method, your environment should contain the following elements after you complete the procedure for IAM Identity Center authentication in the AWS SDKs and Tools Reference Guide:

  • The AWS CLI, which you use to start an AWS access portal session before you run your application.

  • A shared AWSconfig file having a [default] profile with a set of configuration values that can be referenced from the AWS CDK. To find the location of this file, see Location of the shared files in the AWS SDKs and Tools Reference Guide.

  • The shared config file sets the region setting. This sets the default AWS Region the AWS CDK and CDK Toolkit use for AWS requests.

  • The CDK Toolkit uses the profile's SSO token provider configuration to acquire credentials before sending requests to AWS. The sso_role_name value, which is an IAM role connected to an IAM Identity Center permission set, should allow access to the AWS services used in your application.

    The following sample config file shows a default profile set up with SSO token provider configuration. The profile's sso_session setting refers to the named sso-session section. The sso-session section contains settings to initiate an AWS access portal session.

    [default] sso_session = my-sso sso_account_id = 111122223333 sso_role_name = SampleRole region = us-east-1 output = json [sso-session my-sso] sso_region = us-east-1 sso_start_url = sso_registration_scopes = sso:account:access

Start an AWS access portal session

Before accessing AWS services, you need an active AWS access portal session for the CDK Toolkit to use IAM Identity Center authentication to resolve credentials. Depending on your configured session lengths, your access will eventually expire and the CDK Toolkit will encounter an authentication error. Run the following command in the AWS CLI to sign in to the AWS access portal.

aws sso login

If your SSO token provider configuration is using a named profile instead of the default profile, the command is aws sso login --profile NAME. Also specify this profile when issuing cdk commands using the --profile option or the AWS_PROFILE environment variable.

To test if you already have an active session, run the following AWS CLI command.

aws sts get-caller-identity

The response to this command should report the IAM Identity Center account and permission set configured in the shared config file.


If you already have an active AWS access portal session and run aws sso login, you will not be required to provide credentials.

The sign in process may prompt you to allow the AWS CLI access to your data. Since the AWS CLI is built on top of the SDK for Python, permission messages may contain variations of the botocore name.

Specifying Region and other configuration

The CDK Toolkit needs to know the AWS Region that you're deploying into and how to authenticate with AWS. This is needed for deployment operations and to retrieve context values during synthesis. Together, your account and Region make up the environment.

Region may be specified using environment variables or in configuration files. These are the same variables and files used by other AWS tools such as the AWS CLI and the various AWS SDKs. The CDK Toolkit looks for this information in the following order.

  • The AWS_DEFAULT_REGION environment variable.

  • A named profile defined in the standard AWS config file and specified using the --profile option on cdk commands.

  • The [default] section of the standard AWS config file.

Besides specifying AWS authentication and a Region in the [default] section, you can also add one or more [profile NAME] sections, where NAME is the name of the profile. For more information about named profiles, see Shared config and credentials files in the AWS SDKs and Tools Reference Guide.

The standard AWS config file is located at ~/.aws/config (macOS/Linux) or %USERPROFILE%\.aws\config (Windows). For details and alternate locations, see Location of the shared config and credentials files in the AWS SDKs and Tools Reference Guide

The environment that you specify in your AWS CDK app by using the stack's env property is used during synthesis. It's used to generate an environment-specific AWS CloudFormation template, and during deployment, it overrides the account or Region specified by one of the preceding methods. For more information, see Environments.


The AWS CDK uses credentials from the same source files as other AWS tools and SDKs, including the AWS Command Line Interface. However, the AWS CDK might behave somewhat differently from these tools. It uses the AWS SDK for JavaScript under the hood. For complete details on setting up credentials for the AWS SDK for JavaScript, see Setting credentials.

You may optionally use the --role-arn (or -r) option to specify the ARN of an IAM role that should be used for deployment. This role must be assumable by the AWS account being used.

Specifying the app command

Many features of the CDK Toolkit require one or more AWS CloudFormation templates be synthesized, which in turn requires running your application. The AWS CDK supports programs written in a variety of languages. Therefore, it uses a configuration option to specify the exact command necessary to run your app. This option can be specified in two ways.

First, and most commonly, it can be specified using the app key inside the file cdk.json. This is in the main directory of your AWS CDK project. The CDK Toolkit provides an appropriate command when creating a new project with cdk init. Here is the cdk.json from a fresh TypeScript project, for instance.

{ "app": "npx ts-node bin/hello-cdk.ts" }

The CDK Toolkit looks for cdk.json in the current working directory when attempting to run your app. Because of this, you might keep a shell open in your project's main directory for issuing CDK Toolkit commands.

The CDK Toolkit also looks for the app key in ~/.cdk.json (that is, in your home directory) if it can't find it in ./cdk.json. Adding the app command here can be useful if you usually work with CDK code in the same language.

If you are in some other directory, or to run your app using a command other than the one in cdk.json, use the --app (or -a) option to specify it.

cdk --app "npx ts-node bin/hello-cdk.ts" ls

When deploying, you may also specify a directory containing synthesized cloud assemblies, such as cdk.out, as the value of --app. The specified stacks are deployed from this directory; the app is not synthesized.

Specifying stacks

Many CDK Toolkit commands (for example, cdk deploy) work on stacks defined in your app. If your app contains only one stack, the CDK Toolkit assumes you mean that one if you don't specify a stack explicitly.

Otherwise, you must specify the stack or stacks you want to work with. You can do this by specifying the desired stacks by ID individually on the command line. Recall that the ID is the value specified by the second argument when you instantiate the stack.

cdk synth PipelineStack LambdaStack

You may also use wildcards to specify IDs that match a pattern.

  • ? matches any single character

  • * matches any number of characters (* alone matches all stacks)

  • ** matches everything in a hierarchy

You may also use the --all option to specify all stacks.

If your app uses CDK Pipelines, the CDK Toolkit understands your stacks and stages as a hierarchy. Also, the --all option and the * wildcard only match top-level stacks. To match all the stacks, use **. Also use ** to indicate all the stacks under a particular hierarchy.

When using wildcards, enclose the pattern in quotes, or escape the wildcards with \. If you don't, your shell may try to expand the pattern to the names of files in the current directory. At best, this won't do what you expect; at worst, you could deploy stacks you didn't intend to. This isn't strictly necessary on Windows because cmd.exe does not expand wildcards, but is good practice nonetheless.

cdk synth "*Stack" # PipelineStack, LambdaStack, etc. cdk synth 'Stack?' # StackA, StackB, Stack1, etc. cdk synth \* # All stacks in the app, or all top-level stacks in a CDK Pipelines app cdk synth '**' # All stacks in a CDK Pipelines app cdk synth 'PipelineStack/Prod/**' # All stacks in Prod stage in a CDK Pipelines app

The order in which you specify the stacks is not necessarily the order in which they will be processed. The AWS CDK Toolkit accounts for dependencies between stacks when deciding the order in which to process them. For example, let's say that one stack uses a value produced by another (such as the ARN of a resource defined in the second stack). In this case, the second stack is synthesized before the first one because of this dependency. You can add dependencies between stacks manually using the stack's addDependency() method.

Bootstrapping your AWS environment

Deploying stacks with the CDK requires special dedicated AWS CDK resources to be provisioned. The cdk bootstrap command creates the necessary resources for you. You only need to bootstrap if you are deploying a stack that requires these dedicated resources. See Bootstrapping for details.

cdk bootstrap

If issued with no arguments, as shown here, the cdk bootstrap command synthesizes the current app and bootstraps the environments its stacks will be deployed to. If the app contains environment-agnostic stacks, which don't explicitly specify an environment, the default account and Region are bootstrapped, or the environment specified using --profile.

Outside of an app, you must explicitly specify the environment to be bootstrapped. You may also do so to bootstrap an environment that's not specified in your app or local AWS profile. Credentials must be configured (e.g. in ~/.aws/credentials) for the specified account and Region. You may specify a profile that contains the required credentials.

cdk bootstrap ACCOUNT-NUMBER/REGION # e.g. cdk bootstrap 1111111111/us-east-1 cdk bootstrap --profile test 1111111111/us-east-1

Each environment (account/region combination) to which you deploy such a stack must be bootstrapped separately.

You may incur AWS charges for what the AWS CDK stores in the bootstrapped resources. Additionally, if you use -bootstrap-customer-key, an AWS KMS key will be created, which also incurs charges per environment.


Earlier versions of the bootstrap template created a KMS key by default. To avoid charges, re-bootstrap using --no-bootstrap-customer-key.


CDK Toolkit v2 does not support the original bootstrap template, dubbed the legacy template, used by default with CDK v1.


The modern bootstrap template effectively grants the permissions implied by the --cloudformation-execution-policies to any AWS account in the --trust list. By default, this extends permissions to read and write to any resource in the bootstrapped account. Make sure to configure the bootstrapping stack with policies and trusted accounts that you are comfortable with.

Creating a new app

To create a new app, create a directory for it, then, inside the directory, issue cdk init.

mkdir my-cdk-app cd my-cdk-app cdk init TEMPLATE --language LANGUAGE

The supported languages (LANGUAGE) are:













TEMPLATE is an optional template. If the desired template is app, the default, you may omit it. The available templates are:



app (default)

Creates an empty AWS CDK app.


Creates an AWS CDK app with a stack containing an Amazon SQS queue and an Amazon SNS topic.

The templates use the name of the project folder to generate names for files and classes inside your new app.

Listing stacks

To see a list of the IDs of the stacks in your AWS CDK application, enter one of the following equivalent commands:

cdk list cdk ls

If your application contains CDK Pipelines stacks, the CDK Toolkit displays stack names as paths according to their location in the pipeline hierarchy. (For example, PipelineStack, PipelineStack/Prod, and PipelineStack/Prod/MyService.)

If your app contains many stacks, you can specify full or partial stack IDs of the stacks to be listed. For more information, see Specifying stacks.

Add the --long flag to see more information about the stacks, including the stack names and their environments (AWS account and Region).

Synthesizing stacks

The cdk synthesize command (almost always abbreviated synth) synthesizes a stack defined in your app into a CloudFormation template.

cdk synth # if app contains only one stack cdk synth MyStack cdk synth Stack1 Stack2 cdk synth "*" # all stacks in app

The CDK Toolkit actually runs your app and synthesizes fresh templates before most operations (such as when deploying or comparing stacks). These templates are stored by default in the cdk.out directory. The cdk synth command simply prints the generated templates for one or more specified stacks.

See cdk synth --help for all available options. A few of the most frequently used options are covered in the following section.

Specifying context values

Use the --context or -c option to pass runtime context values to your CDK app.

# specify a single context value cdk synth --context key=value MyStack # specify multiple context values (any number) cdk synth --context key1=value1 --context key2=value2 MyStack

When deploying multiple stacks, the specified context values are normally passed to all of them. If you want, you can specify different values for each stack by prefixing the stack name to the context value.

# different context values for each stack cdk synth --context Stack1:key=value Stack2:key=value Stack1 Stack2

Specifying display format

By default, the synthesized template is displayed in YAML format. Add the --json flag to display it in JSON format instead.

cdk synth --json MyStack

Specifying output directory

Add the --output (-o) option to write the synthesized templates to a directory other than cdk.out.

cdk synth --output=~/templates

Deploying stacks

The cdk deploy subcommand deploys one or more specified stacks to your AWS account.

cdk deploy # if app contains only one stack cdk deploy MyStack cdk deploy Stack1 Stack2 cdk deploy "*" # all stacks in app

The CDK Toolkit runs your app and synthesizes fresh AWS CloudFormation templates before deploying anything. Therefore, most command line options you can use with cdk synth (for example, --context) can also be used with cdk deploy.

See cdk deploy --help for all available options. A few of the most useful options are covered in the following section.

Skipping synthesis

The cdk deploy command normally synthesizes your app's stacks before deploying to make sure that the deployment reflects the latest version of your app. If you know that you haven't changed your code since your last cdk synth, you can suppress the redundant synthesis step when deploying. To do so, specify your project's cdk.out directory in the --app option.

cdk deploy --app cdk.out StackOne StackTwo

Disabling rollback

AWS CloudFormation has the ability to roll back changes so that deployments are atomic. This means that they either succeed or fail as a whole. The AWS CDK inherits this capability because it synthesizes and deploys AWS CloudFormation templates.

Rollback makes sure that your resources are in a consistent state at all times, which is vital for production stacks. However, while you're still developing your infrastructure, some failures are inevitable, and rolling back failed deployments can slow you down.

For this reason, the CDK Toolkit lets you disable rollback by adding --no-rollback to your cdk deploy command. With this flag, failed deployments are not rolled back. Instead, resources deployed before the failed resource remain in place, and the next deployment starts with the failed resource. You'll spend a lot less time waiting for deployments and a lot more time developing your infrastructure.

Hot swapping

Use the --hotswap flag with cdk deploy to attempt to update your AWS resources directly instead of generating an AWS CloudFormation change set and deploying it. Deployment falls back to AWS CloudFormation deployment if hot swapping is not possible.

Currently hot swapping supports Lambda functions, Step Functions state machines, and Amazon ECS container images. The --hotswap flag also disables rollback (i.e., implies --no-rollback).


Hot-swapping is not recommended for production deployments.

Watch mode

The CDK Toolkit's watch mode ( cdk deploy --watch, or cdk watch for short) continuously monitors your CDK app's source files and assets for changes. It immediately performs a deployment of the specified stacks when a change is detected.

By default, these deployments use the --hotswap flag, which fast-tracks deployment of changes to Lambda functions. It also falls back to deploying through AWS CloudFormation if you have changed infrastructure configuration. To have cdk watch always perform full AWS CloudFormation deployments, add the --no-hotswap flag to cdk watch.

Any changes made while cdk watch is already performing a deployment are combined into a single deployment, which begins as soon as the in-progress deployment is complete.

Watch mode uses the "watch" key in the project's cdk.json to determine which files to monitor. By default, these files are your application files and assets, but this can be changed by modifying the "include" and "exclude" entries in the "watch" key. The following cdk.json file shows an example of these entries.

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

cdk watch executes the "build" command from cdk.json to build your app before synthesis. If your deployment requires any commands to build or package your Lambda code (or anything else that's not in your CDK app), add it here.

Git-style wildcards, both * and **, can be used in the "watch" and "build" keys. Each path is interpreted relative to the parent directory of cdk.json. The default value of include is **/*, meaning all files and directories in the project root directory. exclude is optional.


Watch mode is not recommended for production deployments.

Specifying AWS CloudFormation parameters

The AWS CDK Toolkit supports specifying AWS CloudFormation parameters at deployment. You may provide these on the command line following the --parameters flag.

cdk deploy MyStack --parameters uploadBucketName=UploadBucket

To define multiple parameters, use multiple --parameters flags.

cdk deploy MyStack --parameters uploadBucketName=UpBucket --parameters downloadBucketName=DownBucket

If you are deploying multiple stacks, you can specify a different value of each parameter for each stack. To do so, prefix the name of the parameter with the stack name and a colon. Otherwise, the same value is passed to all stacks.

cdk deploy MyStack YourStack --parameters MyStack:uploadBucketName=UploadBucket --parameters YourStack:uploadBucketName=UpBucket

By default, the AWS CDK retains values of parameters from previous deployments and uses them in later deployments if they are not specified explicitly. Use the --no-previous-parameters flag to require all parameters to be specified.

Specifying outputs file

If your stack declares AWS CloudFormation outputs, these are normally displayed on the screen at the conclusion of deployment. To write them to a file in JSON format, use the --outputs-file flag.

cdk deploy --outputs-file outputs.json MyStack

Security-related changes

To protect you against unintended changes that affect your security posture, the AWS CDK Toolkit prompts you to approve security-related changes before deploying them. You can specify the level of change that requires approval:

cdk deploy --require-approval LEVEL

LEVEL can be one of the following:




Approval is never required


Requires approval on any IAM or security-group-related change

broadening (default)

Requires approval when IAM statements or traffic rules are added; removals don't require approval

The setting can also be configured in the cdk.json file.

{ "app": "...", "requireApproval": "never" }

Comparing stacks

The cdk diff command compares the current version of a stack (and its dependencies) defined in your app with the already-deployed versions, or with a saved AWS CloudFormation template, and displays a list of changes.

Stack HelloCdkStack
IAM Statement Changes
│   │ Resource                     │ Effect │ Action                       │ Principal                    │ Condition │
│ + │ ${Custom::S3AutoDeleteObject │ Allow  │ sts:AssumeRole               │ │           │
│   │ sCustomResourceProvider/Role │        │                              │                              │           │
│   │ .Arn}                        │        │                              │                              │           │
│ + │ ${MyFirstBucket.Arn}         │ Allow  │ s3:DeleteObject*             │ AWS:${Custom::S3AutoDeleteOb │           │
│   │ ${MyFirstBucket.Arn}/*       │        │ s3:GetBucket*                │ jectsCustomResourceProvider/ │           │
│   │                              │        │ s3:GetObject*                │ Role.Arn}                    │           │
│   │                              │        │ s3:List*                     │                              │           │
IAM Policy Changes
│   │ Resource                                               │ Managed Policy ARN                                     │
│ + │ ${Custom::S3AutoDeleteObjectsCustomResourceProvider/Ro │ {"Fn::Sub":"arn:${AWS::Partition}:iam::aws:policy/serv │
│   │ le}                                                    │ ice-role/AWSLambdaBasicExecutionRole"}                 │
(NOTE: There may be security-related changes not in this list. See

[+] Parameter AssetParameters/4cd61014b71160e8c66fe167e43710d5ba068b80b134e9bd84508cf9238b2392/S3Bucket AssetParameters4cd61014b71160e8c66fe167e43710d5ba068b80b134e9bd84508cf9238b2392S3BucketBF7A7F3F: {"Type":"String","Description":"S3 bucket for asset \"4cd61014b71160e8c66fe167e43710d5ba068b80b134e9bd84508cf9238b2392\""}
[+] Parameter AssetParameters/4cd61014b71160e8c66fe167e43710d5ba068b80b134e9bd84508cf9238b2392/S3VersionKey AssetParameters4cd61014b71160e8c66fe167e43710d5ba068b80b134e9bd84508cf9238b2392S3VersionKeyFAF93626: {"Type":"String","Description":"S3 key for asset version \"4cd61014b71160e8c66fe167e43710d5ba068b80b134e9bd84508cf9238b2392\""}
[+] Parameter AssetParameters/4cd61014b71160e8c66fe167e43710d5ba068b80b134e9bd84508cf9238b2392/ArtifactHash AssetParameters4cd61014b71160e8c66fe167e43710d5ba068b80b134e9bd84508cf9238b2392ArtifactHashE56CD69A: {"Type":"String","Description":"Artifact hash for asset \"4cd61014b71160e8c66fe167e43710d5ba068b80b134e9bd84508cf9238b2392\""}

[+] AWS::S3::BucketPolicy MyFirstBucket/Policy MyFirstBucketPolicy3243DEFD
[+] Custom::S3AutoDeleteObjects MyFirstBucket/AutoDeleteObjectsCustomResource MyFirstBucketAutoDeleteObjectsCustomResourceC52FCF6E
[+] AWS::IAM::Role Custom::S3AutoDeleteObjectsCustomResourceProvider/Role CustomS3AutoDeleteObjectsCustomResourceProviderRole3B1BD092
[+] AWS::Lambda::Function Custom::S3AutoDeleteObjectsCustomResourceProvider/Handler CustomS3AutoDeleteObjectsCustomResourceProviderHandler9D90184F
[~] AWS::S3::Bucket MyFirstBucket MyFirstBucketB8884501
 ├─ [~] DeletionPolicy
 │   ├─ [-] Retain
 │   └─ [+] Delete
 └─ [~] UpdateReplacePolicy
     ├─ [-] Retain
     └─ [+] Delete

To compare your app's stacks with the existing deployment:

cdk diff MyStack

To compare your app's stacks with a saved CloudFormation template:

cdk diff --template ~/stacks/MyStack.old MyStack

Importing existing resources into a stack

You can use the cdk import command to bring resources under the management of CloudFormation for a particular AWS CDK stack. This is useful if you are migrating to AWS CDK, or are moving resources between stacks or changing their logical id. cdk import uses CloudFormation resource imports. See the list of resources that can be imported here.

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

  • Make sure the resource is not currently being managed by any other CloudFormation stack. If it is, first set the removal policy to RemovalPolicy.RETAIN in the stack the resource is currently in and perform a deployment. Then, remove the resource from the stack and perform another deployment. This process will make sure that the resource is no longer managed by CloudFormation but does not delete it.

  • Run a cdk diff to make sure there are no pending changes to the AWS 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.

  • Add constructs for the resources you want to import to your stack. For example, if you want to import an Amazon S3 bucket, add something like new s3.Bucket(this, 'ImportedS3Bucket', {});. Do not make any modifications to any other resource.

    You must also make sure to exactly model the state that the resource currently has into the definition. For the example of the bucket, be sure to include AWS 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.

    You can choose whether or not to include the physical bucket name. We usually recommend to not include resource names into your AWS CDK resource definitions so that it becomes easier to deploy your resources multiple times.

  • Run cdk import STACKNAME.

  • If the resource names are not in your model, the CLI will prompt you to pass in the actual names of the resources you are importing. After this, the import starts.

  • When cdk import reports success, the resource is now managed by AWS CDK and CloudFormation. Any subsequent changes you make to the resource properties in your AWS CDK app the construct configuration will be applied on the next deployment.

  • To confirm that the resource definition in your AWS CDK app matches the current state of the resource, you can start an CloudFormation drift detection operation.

This feature currently does not support importing resources into nested stacks.

Configuration (cdk.json)

Default values for many CDK Toolkit command line flags can be stored in a project's cdk.json file or in the .cdk.json file in your user directory. Following is an alphabetical reference to the supported configuration settings.

Key Notes CDK Toolkit option
app The command that executes the CDK application. --app
assetMetadata If false, CDK does not add metadata to resources that use assets. --no-asset-metadata
bootstrapKmsKeyId Overrides the ID of the AWS KMS key used to encrypt the Amazon S3 deployment bucket. --bootstrap-kms-key-id
build The command that compiles or builds the CDK application before synthesis. Not permitted in ~/.cdk.json. --build
browser The command for launching a Web browser for the cdk docs subcommand. --browser
context See Runtime context. Context values in a configuration file will not be erased by cdk context --clear. (The CDK Toolkit places cached context values in cdk.context.json.) --context
debug If true, CDK Toolkit emits more detailed information useful for debugging. --debug
language The language to be used for initializing new projects. --language
lookups If false, no context lookups are permitted. Synthesis will fail if any context lookups need to be performed. --no-lookups
notices If false, suppresses the display of messages about security vulnerabilities, regressions, and unsupported versions. --no-notices
output The name of the directory into which the synthesized cloud assembly will be emitted (default "cdk.out"). --output
outputsFile The file to which AWS CloudFormation outputs from deployed stacks will be written (in JSON format). --outputs-file
pathMetadata If false, CDK path metadata is not added to synthesized templates. --no-path-metadata
plugin JSON array specifying the package names or local paths of packages that extend the CDK --plugin
profile Name of the default AWS profile used for specifying Region and account credentials. --profile
progress If set to "events", the CDK Toolkit displays all AWS CloudFormation events during deployment, rather than a progress bar. --progress
requireApproval Default approval level for security changes. See Security-related changes --require-approval
rollback If false, failed deployments are not rolled back. --no-rollback
staging If false, assets are not copied to the output directory (use for local debugging of the source files with AWS SAM). --no-staging
tags JSON object containing tags (key-value pairs) for the stack. --tags
toolkitBucketName The name of the Amazon S3 bucket used for deploying assets such as Lambda functions and container images (see Bootstrapping your AWS environment. --toolkit-bucket-name
toolkitStackName The name of the bootstrap stack (see Bootstrapping your AWS environment. --toolkit-stack-name
versionReporting If false, opts out of version reporting. --no-version-reporting
watch JSON object containing "include" and "exclude" keys that indicate which files should (or should not) trigger a rebuild of the project when changed. See Watch mode. --watch