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 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 destroy | Deletes a stack from an AWS account cdk bootstrap | Deploy a toolkit stack to support deploying large stacks & artifacts cdk doctor | Inspect the environment and produce information useful for troubleshooting

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 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 cloudFormation template output to STDOUT
$ cdk synth MyStackName --quiet

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). This command returns non-zero if any differences are found.

$ # 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

cdk deploy

Deploys a stack of your CDK app to it's 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.

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 you want to deploy all of them, you can use the flag --all or the wildcard * to deploy all stacks in an app.

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_10_X
});

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

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)

Externally Executable CloudFormation Change Sets

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

$ cdk deploy --no-execute

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 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.

$ # 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 needs, policies, or requirements not met by the default template, you can customize it to fit your own situation, by exporting the default 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

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

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

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')
    "context": {                      // Context entries                   (--context=key=value)
        "key": "value"
    },
    "toolkitStackName": "foo",        // Customize 'bootstrap' stack name  (--toolkit-stack-name=foo)
    "toolkitBucketName": "fooBucket", // Customize 'bootstrap' bucket name (--toolkit-bucket-name=fooBucket)
    "versionReporting": false,         // Opt-out of version reporting      (--no-version-reporting)
}

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.