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CDK constructs for defining an interaction between an AWS Lambda function and an AWS Step Function.

Project description

aws-lambda-step-function module

---

Stability: Deprecated

Some of our early constructs don’t meet the naming standards that evolved for the library. We are releasing completely feature compatible versions with corrected names. The underlying implementation code is the same regardless of whether you deploy the construct using the old or new name. We will support both names for all 1.x releases, but in 2.x we will only publish the correctly named constructs. This construct is being replaced by the functionally identical aws-lambda-stepfunctions.


Reference Documentation: https://docs.aws.amazon.com/solutions/latest/constructs/
Language Package
Python Logo Python aws_solutions_constructs.aws_lambda_step_function
Typescript Logo Typescript @aws-solutions-constructs/aws-lambda-step-function
Java Logo Java software.amazon.awsconstructs.services.lambdastepfunction

Overview

This AWS Solutions Construct implements an AWS Lambda function connected to an AWS Step Function.

Here is a minimal deployable pattern definition:

Typescript

// aws-lambda-step-function has been deprecated for CDK V2 in favor of aws-lambda-stepfunctions.
// This sample uses the CDK V1 syntax
import * as cdk from '@aws-cdk/core';
import * as stepfunctions from '@aws-cdk/aws-stepfunctions';
import * as lambda from '@aws-cdk/aws-lambda';
import { LambdaToStepFunction } from '@aws-solutions-constructs/aws-lambda-step-function';

const startState = new stepfunctions.Pass(this, 'StartState');

new LambdaToStepFunction(this, 'LambdaToStepFunctionPattern', {
  lambdaFunctionProps: {
    runtime: lambda.Runtime.NODEJS_14_X,
    handler: 'index.handler',
    code: lambda.Code.fromAsset(`lambda`)
  },
  stateMachineProps: {
    definition: startState
  }
});

Python

# aws-lambda-step-function has been deprecated for CDK V2 in favor of aws-lambda-stepfunctions.
# This sample uses the CDK V1 syntax
from aws_solutions_constructs.aws_lambda_step_function import LambdaToStepFunction
from aws_cdk import (
    aws_lambda as _lambda,
    aws_stepfunctions as stepfunctions,
    core
)

start_state = stepfunctions.Pass(self, 'start_state')

LambdaToStepFunction(
    self, 'test-lambda-stepfunctions-stack',
    lambda_function_props=_lambda.FunctionProps(
        code=_lambda.Code.from_asset('lambda'),
        runtime=_lambda.Runtime.PYTHON_3_9,
        handler='index.handler'
    ),
    state_machine_props=stepfunctions.StateMachineProps(
        definition=start_state)
)

Java

// aws-lambda-step-function has been deprecated for CDK V2 in favor of aws-lambda-stepfunctions.
// This sample uses the CDK V1 syntax
import software.constructs.Construct;

import software.amazon.awscdk.core.*;
import software.amazon.awscdk.services.lambda.*;
import software.amazon.awscdk.services.lambda.Runtime;
import software.amazon.awscdk.services.stepfunctions.*;
import software.amazon.awsconstructs.services.lambdastepfunction.*;

final Pass startState = new Pass(this, "StartState");

new LambdaToStepFunction(this, "test-lambda-stepfunctions-stack",
        new LambdaToStepFunctionProps.Builder()
                .lambdaFunctionProps(new FunctionProps.Builder()
                        .runtime(Runtime.NODEJS_14_X)
                        .code(Code.fromAsset("lambda"))
                        .handler("index.handler")
                        .build())
                .stateMachineProps(new StateMachineProps.Builder()
                        .definition(startState)
                        .build())
                .build());

Pattern Construct Props

Name Type Description
existingLambdaObj? lambda.Function Existing instance of Lambda Function object, providing both this and lambdaFunctionProps will cause an error.
lambdaFunctionProps? lambda.FunctionProps User provided props to override the default props for the Lambda function.
stateMachineProps sfn.StateMachineProps User provided props for the sfn.StateMachine.
createCloudWatchAlarms boolean Whether to create recommended CloudWatch alarms
logGroupProps? logs.LogGroupProps User provided props to override the default props for for the CloudWatchLogs LogGroup.
stateMachineEnvironmentVariableName? string Optional Name for the Lambda function environment variable set to the ARN of the state machine. Default: STATE_MACHINE_ARN
existingVpc? ec2.IVpc An optional, existing VPC into which this pattern should be deployed. When deployed in a VPC, the Lambda function will use ENIs in the VPC to access network resources and an Interface Endpoint will be created in the VPC for Amazon Step Functions. If an existing VPC is provided, the deployVpc property cannot be true. This uses ec2.IVpc to allow clients to supply VPCs that exist outside the stack using the ec2.Vpc.fromLookup() method.
vpcProps? ec2.VpcProps Optional user-provided properties to override the default properties for the new VPC. enableDnsHostnames, enableDnsSupport, natGateways and subnetConfiguration are set by the pattern, so any values for those properties supplied here will be overrriden. If deployVpc is not true then this property will be ignored.
deployVpc? boolean Whether to create a new VPC based on vpcProps into which to deploy this pattern. Setting this to true will deploy the minimal, most private VPC to run the pattern:
  • One isolated subnet in each Availability Zone used by the CDK program
  • enableDnsHostnames and enableDnsSupport will both be set to true
If this property is true then existingVpc cannot be specified. Defaults to false.

Pattern Properties

Name Type Description
lambdaFunction lambda.Function Returns an instance of the Lambda function created by the pattern.
stateMachine sfn.StateMachine Returns an instance of StateMachine created by the construct.
stateMachineLogGroup logs.ILogGroup Returns an instance of the ILogGroup created by the construct for StateMachine
cloudwatchAlarms? cloudwatch.Alarm[] Returns a list of alarms created by the construct.
vpc? ec2.IVpc Returns an interface on the VPC used by the pattern (if any). This may be a VPC created by the pattern or the VPC supplied to the pattern constructor.

Default settings

Out of the box implementation of the Construct without any override will set the following defaults:

AWS Lambda Function

  • Configure limited privilege access IAM role for Lambda function

  • Enable reusing connections with Keep-Alive for NodeJs Lambda function

  • Enable X-Ray Tracing

  • Set Environment Variables

    • (default) STATE_MACHINE_ARN
    • AWS_NODEJS_CONNECTION_REUSE_ENABLED (for Node 10.x and higher functions)

AWS Step Function

  • Enable CloudWatch logging for API Gateway
  • Deploy best practices CloudWatch Alarms for the Step Function

Architecture

Architecture Diagram


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