aws-lambda-stepfunctions

Reference Documentation:

https://docs.aws.amazon.com/solutions/latest/constructs/

Language	Package
Python	aws_solutions_constructs.aws_lambda_stepfunctions
Typescript	@aws-solutions-constructs/aws-lambda-stepfunctions
Java	software.amazon.awsconstructs.services.lambdastepfunctions

Overview

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

Here is a minimal deployable pattern definition:

Typescript

import { Construct } from 'constructs';
import { Stack, StackProps } from 'aws-cdk-lib';
import { LambdaToStepfunctions } from '@aws-solutions-constructs/aws-lambda-stepfunctions';
import * as stepfunctions from 'aws-cdk-lib/aws-stepfunctions';
import * as lambda from 'aws-cdk-lib/aws-lambda';

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

new LambdaToStepfunctions(this, 'LambdaToStepfunctionsPattern', {
  lambdaFunctionProps: {
    runtime: lambda.Runtime.NODEJS_22_X,
    handler: 'index.handler',
    code: lambda.Code.fromAsset(`lambda`)
  },
  stateMachineProps: {
    definition: startState
  }
});

Python

from aws_solutions_constructs.aws_lambda_stepfunctions import LambdaToStepfunctions
from aws_cdk import (
    aws_lambda as _lambda,
    aws_stepfunctions as stepfunctions,
    Stack
)
from constructs import Construct

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

LambdaToStepfunctions(
    self, 'test-lambda-stepfunctions-stack',
    lambda_function_props=_lambda.FunctionProps(
        code=_lambda.Code.from_asset('lambda'),
        runtime=_lambda.Runtime.PYTHON_3_11,
        handler='index.handler'
    ),
    state_machine_props=stepfunctions.StateMachineProps(
        definition=start_state)
)

Java

import software.constructs.Construct;

import software.amazon.awscdk.Stack;
import software.amazon.awscdk.StackProps;
import software.amazon.awscdk.services.lambda.*;
import software.amazon.awscdk.services.lambda.Runtime;
import software.amazon.awscdk.services.stepfunctions.*;
import software.amazon.awsconstructs.services.lambdastepfunctions.*;

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

new LambdaToStepfunctions(this, "test-lambda-stepfunctions-stack",
        new LambdaToStepfunctionsProps.Builder()
                .lambdaFunctionProps(new FunctionProps.Builder()
                        .runtime(Runtime.NODEJS_22_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 overridden. 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:

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 Functions

• Enable CloudWatch logging for API Gateway

• Deploy best practices CloudWatch Alarms for the Step Functions

Architecture

Example Lambda Function Implementation

While Solutions Constructs does not publish code for the Lambda function to work with Step Functions, here are several examples: 'examples'. (these examples are in Python, but examples in other languages can also be found at this site)

Github

Go to the Github repo for this pattern to view the code, read/create issues and pull requests and more.