fn Submodule

Constructs

FailedInvocations

A dead-letter queue for Lambda invocations that failed, and an alarm for it.

Async invocations and stream event sources send their failure records here. The alarm goes to ALARM while the queue holds any messages.

Initializers 

import { fn } from 'shady-island'

new fn.FailedInvocations(scope: Construct, id: string, props?: FailedInvocationsProps)
Name Type Description
scope constructs.Construct - The scope in which to define this construct.
id string - The scoped construct ID.
props FailedInvocationsProps - Initialization properties for this construct.
scopeRequired

The scope in which to define this construct.

idRequired

The scoped construct ID.

propsOptional

Initialization properties for this construct.

Methods

Name Description
toString Returns a string representation of this construct.
with Applies one or more mixins to this construct.
capture Sends a Lambda function’s failed async invocations to the queue.
toString 
public toString(): string

Returns a string representation of this construct.

with 
public with(mixins: ...IMixin[]): IConstruct

Applies one or more mixins to this construct.

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

mixinsRequired

The mixins to apply.

capture 
public capture(fn: IFunction, options?: CaptureOptions): void

Sends a Lambda function’s failed async invocations to the queue.

fnRequired

The function, invoked asynchronously by S3, SNS, or another Lambda.

optionsOptional

Configuration options for the async invocation.

Static Functions

Name Description
isConstruct Checks if x is a construct.
isConstruct 
import { fn } from 'shady-island'

fn.FailedInvocations.isConstruct(x: any)

Checks if x is a construct.

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

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

xRequired

Any object.

Properties

Name Type Description
node constructs.Node The tree node.
alarm aws-cdk-lib.aws_cloudwatch.Alarm The alarm on visible messages in the queue.
eventSourceDlq aws-cdk-lib.aws_lambda.IEventSourceDlq The destination to pass as onFailure to a stream event source.
queue aws-cdk-lib.aws_sqs.IQueue The dead-letter queue.
nodeRequired 
public readonly node: Node;

The tree node.

alarmRequired 
public readonly alarm: Alarm;

The alarm on visible messages in the queue.

eventSourceDlqRequired 
public readonly eventSourceDlq: IEventSourceDlq;

The destination to pass as onFailure to a stream event source.

Example

const failures = new FailedInvocations(this, "FailedInvocations");
fn.addEventSource(
  new DynamoEventSource(table, {
    startingPosition: StartingPosition.TRIM_HORIZON,
    retryAttempts: 10,
    onFailure: failures.eventSourceDlq,
  })
);
queueRequired 
public readonly queue: IQueue;

The dead-letter queue.

Structs

CaptureOptions

Options for capturing a function’s failed async invocations.

Initializer 

import { fn } from 'shady-island'

const captureOptions: fn.CaptureOptions = { ... }

Properties

Name Type Description
maxEventAge aws-cdk-lib.Duration The longest time Lambda keeps an event before giving up on it.
retryAttempts number How many times Lambda retries a failed invocation.
maxEventAgeOptional 
public readonly maxEventAge: Duration;

The longest time Lambda keeps an event before giving up on it.

retryAttemptsOptional 
public readonly retryAttempts: number;

How many times Lambda retries a failed invocation.

FailedInvocationsProps

Constructor properties for FailedInvocations.

Initializer 

import { fn } from 'shady-island'

const failedInvocationsProps: fn.FailedInvocationsProps = { ... }

Properties

Name Type Description
alarmDescription string The alarm’s description.
alarmPeriod aws-cdk-lib.Duration How long the queue must hold messages before the alarm goes off.
queue aws-cdk-lib.aws_sqs.IQueue An existing queue to alarm on, instead of creating one.
queueProps aws-cdk-lib.aws_sqs.QueueProps Properties for the new queue, such as fifo or encryptionMasterKey.
alarmDescriptionOptional 
public readonly alarmDescription: string;

The alarm’s description.

alarmPeriodOptional 
public readonly alarmPeriod: Duration;

How long the queue must hold messages before the alarm goes off.

queueOptional 
public readonly queue: IQueue;

An existing queue to alarm on, instead of creating one.

Example

const failures = new FailedInvocations(this, "FailedInvocations", {
  queue: Queue.fromQueueArn(this, "Queue", deadLetterQueueArn),
});
queuePropsOptional 
public readonly queueProps: QueueProps;

Properties for the new queue, such as fifo or encryptionMasterKey.

Example

const failures = new FailedInvocations(this, "FailedInvocations", {
  queueProps: {
    encryption: QueueEncryption.KMS,
    encryptionMasterKey: key,
    retentionPeriod: Duration.days(7),
  },
});

PowertoolsLayerOptions

Options for calling the PowertoolsLayer methods.

Initializer 

import { fn } from 'shady-island'

const powertoolsLayerOptions: fn.PowertoolsLayerOptions = { ... }

Properties

Name Type Description
layerVersion number The version of the Lambda Layer desired.
version string The version of Powertools desired.
layerVersionOptional 
public readonly layerVersion: number;

The version of the Lambda Layer desired.

Overrides {@link version}.

versionOptional 
public readonly version: string;

The version of Powertools desired.

Ignored if you specify layerVersion.

PowertoolsPythonOptions

Options for calling the PowertoolsLayer.forPythonV3 method.

Initializer 

import { fn } from 'shady-island'

const powertoolsPythonOptions: fn.PowertoolsPythonOptions = { ... }

Properties

Name Type Description
layerVersion number The version of the Lambda Layer desired.
version string The version of Powertools desired.
pythonVersion string The Python version (e.g. 3.10, 3.14).
architecture aws-cdk-lib.aws_lambda.Architecture The CPU architecture for the Lambda function.
layerVersionOptional 
public readonly layerVersion: number;

The version of the Lambda Layer desired.

Overrides {@link version}.

versionOptional 
public readonly version: string;

The version of Powertools desired.

Ignored if you specify layerVersion.

pythonVersionRequired 
public readonly pythonVersion: string;

The Python version (e.g. 3.10, 3.14).

architectureOptional 
public readonly architecture: Architecture;

The CPU architecture for the Lambda function.

PowertoolsTypeScriptOptions

Options for calling the PowertoolsLayer.forTypeScriptV2 method.

Initializer 

import { fn } from 'shady-island'

const powertoolsTypeScriptOptions: fn.PowertoolsTypeScriptOptions = { ... }

Properties

Name Type Description
layerVersion number The version of the Lambda Layer desired.
version string The version of Powertools desired.
layerVersionOptional 
public readonly layerVersion: number;

The version of the Lambda Layer desired.

Overrides {@link version}.

versionOptional 
public readonly version: string;

The version of Powertools desired.

Ignored if you specify layerVersion.

Classes

PowertoolsLayer

Provides Lambda Layers for Powertools.

PowertoolsLayer.forTypeScriptV2(scope);
PowertoolsLayer.forTypeScriptV2(scope, { version: "2.34.0" });
PowertoolsLayer.forTypeScriptV2(scope, { layerVersion: 49 });

PowertoolsLayer.forPythonV3(scope, { pythonVersion: "3.14" });
PowertoolsLayer.forPythonV3(scope, { pythonVersion: "3.14", architecture: Architecture.ARM_64 });
PowertoolsLayer.forPythonV3(scope, { pythonVersion: "3.14", version: "3.31.1" });
PowertoolsLayer.forPythonV3(scope, { pythonVersion: "3.14", layerVersion: 36 });

Initializers 

import { fn } from 'shady-island'

new fn.PowertoolsLayer()

| Name | Type | Description | | — | — | — |

Static Functions

Name Description
forPythonV3 Get the Lambda Layer for Python V3.
forTypeScriptV2 Get the Lambda Layer for TypeScript V2.
forPythonV3 
import { fn } from 'shady-island'

fn.PowertoolsLayer.forPythonV3(scope: Construct, options: PowertoolsPythonOptions)

Get the Lambda Layer for Python V3.

If you supply neither “version” nor “layerVersion”, the latest possible version of the Layer is returned by looking it up in SSM Parameter Store.

If you supply the “version” option, the Layer is returned by looking it up in SSM Parameter Store.

If you supply the “layerVersion” option, SSM is not involved.

scopeRequired

The parent scope.

optionsRequired

The configuration options.

forTypeScriptV2 
import { fn } from 'shady-island'

fn.PowertoolsLayer.forTypeScriptV2(scope: Construct, options?: PowertoolsTypeScriptOptions)

Get the Lambda Layer for TypeScript V2.

If you supply neither “version” nor “layerVersion”, the latest possible version of the Layer is returned by looking it up in SSM Parameter Store.

If you supply the “version” option, the Layer is returned by looking it up in SSM Parameter Store.

If you supply the “layerVersion” option, SSM is not involved.

scopeRequired

The parent scope.

optionsOptional

The configuration options.