Metadata-Version: 2.1
Name: aws-cdk.custom-resources
Version: 1.16.3
Summary: Constructs for implementing CDK custom resources
Home-page: https://github.com/aws/aws-cdk
Author: Amazon Web Services
License: Apache-2.0
Project-URL: Source, https://github.com/aws/aws-cdk.git
Description: # AWS CDK Custom Resources
        
        <html></html>---
        
        
        ![Stability: Experimental](https://img.shields.io/badge/stability-Experimental-important.svg?style=for-the-badge)
        
        > **This is a *developer preview* (public beta) module. Releases might lack important features and might have
        > future breaking changes.**
        >
        > This API is still under active development and subject to non-backward
        > compatible changes or removal in any future version. Use of the API is not recommended in production
        > environments. Experimental APIs are not subject to the Semantic Versioning model.
        
        ---
        <html></html>
        
        * [Provider Framework](#provider-framework)
        
          * [Handling Lifecycle Events: onEvent](#handling-lifecycle-events-onevent)
          * [Asynchronous Providers: isComplete](#asynchronous-providers-iscomplete)
          * [Physical Resource IDs](#physical-resource-ids)
          * [Error Handling](#error-handling)
          * [Execution Policy](#execution-policy)
          * [Timeouts](#timeouts)
          * [Examples](#examples)
        * [Custom Resources for AWS APIs](#custom-resources-for-aws-apis)
        
          * [Execution Policy](#execution-policy-1)
          * [Examples](#examples-1)
        
        ## Provider Framework
        
        AWS CloudFormation [custom resources]((https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/template-custom-resources.html).) are extension points to the provisioning
        engine. When CloudFormation needs to create, update or delete a custom resource,
        it sends a lifecycle event notification to a **custom resource provider**. The provider
        handles the event (e.g. creates a resource) and sends back a response to CloudFormation.
        
        The `@aws-cdk/custom-resources.Provider` construct is a "mini-framework" for
        implementing providers for AWS CloudFormation custom resources. The framework offers a high-level API which makes it easier to implement robust
        and powerful custom resources and includes the following capabilities:
        
        * Handles responses to AWS CloudFormation and protects against blocked
          deployments
        * Validates handler return values to help with correct handler implementation
        * Supports asynchronous handlers to enable long operations which can exceed the AWS Lambda timeout
        * Implements default behavior for physical resource IDs.
        
        The following code shows how the `Provider` construct is used in conjunction
        with `cfn.CustomResource` and a user-provided AWS Lambda function which
        implements the actual handler.
        
        ```python
        # Example may have issues. See https://github.com/aws/jsii/issues/826
        import aws_cdk.custom_resources as cr
        import aws_cdk.aws_cloudformation as cfn
        
        on_event = lambda.Function(self, "MyHandler")
        
        my_provider = cr.Provider(self, "MyProvider",
            on_event_handler=on_event
        )
        
        cfn.CustomResource(self, "Resource1", provider=my_provider)
        cfn.CustomResource(self, "Resource2", provider=my_provider)
        ```
        
        Providers are implemented through AWS Lambda functions that are triggered by the
        provider framework in response to lifecycle events.
        
        At the minimum, users must define the `onEvent` handler, which is invoked by the
        framework for all resource lifecycle events (`Create`, `Update` and `Delete`)
        and returns a result which is then submitted to CloudFormation.
        
        Users may also provide an additional handler called `isComplete`, for cases
        where the lifecycle operation cannot be completed immediately. The
        `isComplete` handler will be retried asynchronously after `onEvent` until it
        returns `IsComplete: true`, or until the total provider timeout has expired.
        
        ### Handling Lifecycle Events: onEvent
        
        The user-defined `onEvent` AWS Lambda function is invoked whenever a resource
        lifecycle event occurs. The function is expected to handle the event and return
        a response to the framework that, at least, includes the physical resource ID.
        
        If `onEvent` returns successfully, the framework will submit a "SUCCESS" response
        to AWS CloudFormation for this resource operation.  If the provider is
        [asynchronous](#asynchronous-providers-iscomplete) (`isCompleteHandler` is
        defined), the framework will only submit a response based on the result of
        `isComplete`.
        
        If `onEvent` throws an error, the framework will submit a "FAILED" response to
        AWS CloudFormation.
        
        The input event includes the following fields derived from the [Custom Resource
        Provider Request](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/crpg-ref-requests.html#crpg-ref-request-fields):
        
        |Field|Type|Description
        |-----|----|----------------
        |`RequestType`|String|The type of lifecycle event: `Create`, `Update` or `Delete`.
        |`LogicalResourceId`|String|The template developer-chosen name (logical ID) of the custom resource in the AWS CloudFormation template.
        |`PhysicalResourceId`|String|This field will only be present for `Update` and `Delete` events and includes the value returned in `PhysicalResourceId` of the previous operation.
        |`ResourceProperties`|JSON|This field contains the properties defined in the template for this custom resource.
        |`OldResourceProperties`|JSON|This field will only be present for `Update` events and contains the resource properties that were declared previous to the update request.
        |`ResourceType`|String|The resource type defined for this custom resource in the template. A provider may handle any number of custom resource types.
        |`RequestId`|String|A unique ID for the request.
        |`StackId`|String|The ARN that identifies the stack that contains the custom resource.
        
        The return value from `onEvent` must be a JSON object with the following fields:
        
        |Field|Type|Required|Description
        |-----|----|--------|-----------
        |`PhysicalResourceId`|String|No|The allocated/assigned physical ID of the resource. If omitted for `Create` events, the event's `RequestId` will be used. For `Update`, the current physical ID will be used. If a different value is returned, CloudFormation will follow with a subsequent `Delete` for the previous ID (resource replacement). For `Delete`, it will always return the current physical resource ID, and if the user returns a different one, an error will occur.
        |`Data`|JSON|No|Resource attributes, which can later be retrieved through `Fn::GetAtt` on the custom resource object.
        
        ### Asynchronous Providers: isComplete
        
        It is not uncommon for the provisioning of resources to be an asynchronous
        operation, which means that the operation does not immediately finish, and we
        need to "wait" until the resource stabilizes.
        
        The provider framework makes it easy to implement "waiters" by allowing users to
        specify an additional AWS Lambda function in `isCompleteHandler`.
        
        The framework will repeatedly invoke the handler every `queryInterval`. When
        `isComplete` returns with `IsComplete: true`, the framework will submit a
        "SUCCESS" response to AWS CloudFormation. If `totalTimeout` expires and the
        operation has not yet completed, the framework will submit a "FAILED" response
        with the message "Operation timed out".
        
        If an error is thrown, the framework will submit a "FAILED" response to AWS
        CloudFormation.
        
        The input event to `isComplete` is similar to
        [`onEvent`](#handling-lifecycle-events-onevent), with an additional guarantee
        that `PhysicalResourceId` is defines and contains the value returned from
        `onEvent` or the described default. At any case, it is guaranteed to exist.
        
        The return value must be a JSON object with the following fields:
        
        |Field|Type|Required|Description
        |-----|----|--------|-----------
        |`IsComplete`|Boolean|Yes|Indicates if the operation has finished or not.
        |`Data`|JSON|No|May only be sent if `IsComplete` is `true` and includes additional resource attributes. These attributes will be **merged** with the ones returned from `onEvent`
        
        ### Physical Resource IDs
        
        Every resource in CloudFormation has a physical resource ID. When a resource is
        created, the `PhysicalResourceId` returned from the `Create` operation is stored
        by AWS CloudFormation and assigned to the logical ID defined for this resource
        in the template. If a `Create` operation returns without a `PhysicalResourceId`,
        the framework will use `RequestId` as the default. This is sufficient for
        various cases such as "pseudo-resources" which only query data.
        
        For `Update` and `Delete` operations, the resource event will always include the
        current `PhysicalResourceId` of the resource.
        
        When an `Update` operation occurs, the default behavior is to return the current
        physical resource ID. if the `onEvent` returns a `PhysicalResourceId` which is
        different from the current one, AWS CloudFormation will treat this as a
        **resource replacement**, and it will issue a subsequent `Delete` operation for
        the old resource.
        
        As a rule of thumb, if your custom resource supports configuring a physical name
        (e.g. you can specify a `BucketName` when you define an `AWS::S3::Bucket`), you
        must return this name in `PhysicalResourceId` and make sure to handle
        replacement properly. The `S3File` example demonstrates this
        through the `objectKey` property.
        
        ### Error Handling
        
        As mentioned above, if any of the user handlers fail (i.e. throws an exception)
        or times out (due to their AWS Lambda timing out), the framework will trap these
        errors and submit a "FAILED" response to AWS CloudFormation, along with the error
        message.
        
        Since errors can occur in multiple places in the provider (framework, `onEvent`,
        `isComplete`), it is important to know that there could situations where a
        resource operation fails even though the operation technically succeeded (i.e.
        isComplete throws an error).
        
        When AWS CloudFormation receives a "FAILED" response, it will attempt to roll
        back the stack to it's last state. This has different meanings for different
        lifecycle events:
        
        * If a `Create` event fails, CloudFormation will issue a `Delete` event to allow
          the provider to clean up any unfinished work related to the creation of the
          resource. The implication of this is that it is recommended to implement
          `Delete` in an idempotent way, in order to make sure that the rollback
          `Delete` operation won't fail if a resource creation has failed.
        * If an `Update` event fails, CloudFormation will issue an additional `Update`
          with the previous properties.
        * If a `Delete` event fails, CloudFormation will abandon this resource.
        
        ### Execution Policy
        
        Similarly to any AWS Lambda function, if the user-defined handlers require
        access to AWS resources, you will have to define these permissions
        by calling "grant" methods such as `myBucket.grantRead(myHandler)`), using `myHandler.addToRolePolicy`
        or specifying an `initialPolicy` when defining the function.
        
        Bear in mind that in most cases, a single provider will be used for multiple
        resource instances. This means that the execution policy of the provider must
        have the appropriate privileges.
        
        The following example grants the `onEvent` handler `s3:GetObject*` permissions
        to all buckets:
        
        ```python
        # Example may have issues. See https://github.com/aws/jsii/issues/826
        lambda.Function(self, "OnEventHandler",
            # ...
            initial_policy=[
                iam.PolicyStatement(actions=["s3:GetObject*"], resources=["*"])
            ]
        )
        ```
        
        ### Timeouts
        
        Users are responsible to define the timeouts for the AWS Lambda functions for
        user-defined handlers. It is recommended not to exceed a **14 minutes** timeout,
        since all framework functions are configured to time out after 15 minutes, which
        is the maximal AWS Lambda timeout.
        
        If your operation takes over **14 minutes**, the recommended approach is to
        implement an [asynchronous provider](#asynchronous-providers-iscomplete), and
        then configure the timeouts for the asynchronous retries through the
        `queryInterval` and the `totalTimeout` options.
        
        ### Examples
        
        This module includes a few examples for custom resource implementations:
        
        #### S3File
        
        Provisions an object in an S3 bucket with textual contents. See the source code
        for the
        [construct](test/provider-framework/integration-test-fixtures/s3-file.ts) and
        [handler](test/provider-framework/integration-test-fixtures/s3-file-handler/index.ts).
        
        The following example will create the file `folder/file1.txt` inside `myBucket`
        with the contents `hello!`.
        
        ```python
        # Example may have issues. See https://github.com/aws/jsii/issues/826
        S3File(self, "MyFile",
            bucket=my_bucket,
            object_key="folder/file1.txt", # optional
            content="hello!",
            public=True
        )
        ```
        
        This sample demonstrates the following concepts:
        
        * Synchronous implementation (`isComplete` is not defined)
        * Automatically generates the physical name if `objectKey` is not defined
        * Handles physical name changes
        * Returns resource attributes
        * Handles deletions
        * Implemented in TypeScript
        
        #### S3Assert
        
        Checks that the textual contents of an S3 object matches a certain value. The check will be retried for 5 minutes as long as the object is not found or the value is different. See the source code for the [construct](test/provider-framework/integration-test-fixtures/s3-assert.ts) and [handler](test/provider-framework/integration-test-fixtures/s3-assert-handler/index.py).
        
        The following example defines an `S3Assert` resource which waits until
        `myfile.txt` in `myBucket` exists and includes the contents `foo bar`:
        
        ```python
        # Example may have issues. See https://github.com/aws/jsii/issues/826
        S3Assert(self, "AssertMyFile",
            bucket=my_bucket,
            object_key="myfile.txt",
            expected_content="foo bar"
        )
        ```
        
        This sample demonstrates the following concepts:
        
        * Asynchronous implementation
        * Non-intrinsic physical IDs
        * Implemented in Python
        
        ## Custom Resources for AWS APIs
        
        Sometimes a single API call can fill the gap in the CloudFormation coverage. In
        this case you can use the `AwsCustomResource` construct. This construct creates
        a custom resource that can be customized to make specific API calls for the
        `CREATE`, `UPDATE` and `DELETE` events. Additionally, data returned by the API
        call can be extracted and used in other constructs/resources (creating a real
        CloudFormation dependency using `Fn::GetAtt` under the hood).
        
        The physical id of the custom resource can be specified or derived from the data
        returned by the API call.
        
        The `AwsCustomResource` uses the AWS SDK for JavaScript. Services, actions and
        parameters can be found in the [API documentation](https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/index.html).
        
        Path to data must be specified using a dot notation, e.g. to get the string value
        of the `Title` attribute for the first item returned by `dynamodb.query` it should
        be `Items.0.Title.S`.
        
        ### Execution Policy
        
        IAM policy statements required to make the API calls are derived from the calls
        and allow by default the actions to be made on all resources (`*`). You can
        restrict the permissions by specifying your own list of statements with the
        `policyStatements` prop. The custom resource also implements `iam.IGrantable`,
        making it possible to use the `grantXxx()` methods.
        
        As this custom resource uses a singleton Lambda function, it's important to note
        that the function's role will eventually accumulate the permissions/grants from all
        resources.
        
        Chained API calls can be achieved by creating dependencies:
        
        ```python
        # Example may have issues. See https://github.com/aws/jsii/issues/826
        aws_custom1 = AwsCustomResource(self, "API1",
            on_create={
                "service": "...",
                "action": "...",
                "physical_resource_id": "..."
            }
        )
        
        aws_custom2 = AwsCustomResource(self, "API2",
            on_create={
                "service": "...",
                "action": "...",
                "parameters": {
                    "text": aws_custom1.get_data("Items.0.text")
                },
                "physical_resource_id": "..."
            }
        )
        ```
        
        ### Examples
        
        #### Verify a domain with SES
        
        ```python
        # Example may have issues. See https://github.com/aws/jsii/issues/826
        verify_domain_identity = AwsCustomResource(self, "VerifyDomainIdentity",
            on_create={
                "service": "SES",
                "action": "verifyDomainIdentity",
                "parameters": {
                    "Domain": "example.com"
                },
                "physical_resource_id_path": "VerificationToken"
            }
        )
        
        route53.TxtRecord(zone, "SESVerificationRecord",
            record_name="_amazonses.example.com",
            record_value=verify_domain_identity.get_data("VerificationToken")
        )
        ```
        
        #### Get the latest version of a secure SSM parameter
        
        ```python
        # Example may have issues. See https://github.com/aws/jsii/issues/826
        get_parameter = AwsCustomResource(self, "GetParameter",
            on_update={# will also be called for a CREATE event
                "service": "SSM",
                "action": "getParameter",
                "parameters": {
                    "Name": "my-parameter",
                    "WithDecryption": True
                },
                "physical_resource_id": Date.now().to_string()}
        )
        
        # Use the value in another construct with
        get_parameter.get_data("Parameter.Value")
        ```
        
        ---
        
        
        This module is part of the [AWS Cloud Development Kit](https://github.com/aws/aws-cdk) project.
        
Platform: UNKNOWN
Classifier: Intended Audience :: Developers
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python :: 3
Classifier: Development Status :: 4 - Beta
Classifier: License :: OSI Approved
Requires-Python: >=3.6
Description-Content-Type: text/markdown
