Step Functions Integration Without Role Permissions

What this rule checks

A Step Functions definition declares a service integration (lambda:invoke, dynamodb:getItem, sqs:sendMessage, sns:publish, states:startExecution) targeting an in-template resource, but the state machine role lacks the required action. Task states fail at execution time. Statically unparseable definitions are skipped.

How to fix it

1. 1Build the state machine with CDK L2 task constructs (sfn_tasks.LambdaInvoke, DynamoGetItem, SqsSendMessage, ...) which grant the execution role automatically
2. 2Or grant the state machine role the integration's required action (e.g. lambda:InvokeFunction, dynamodb:GetItem) scoped to the target resource

import * as cdk from 'aws-cdk-lib';
import * as iam from 'aws-cdk-lib/aws-iam';
import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as sfn from 'aws-cdk-lib/aws-stepfunctions';

const fn = new lambda.Function(this, 'Fn', {
  runtime: lambda.Runtime.NODEJS_20_X,
  handler: 'index.handler',
  code: lambda.Code.fromInline('exports.handler = async () => {};'),
});

const role = new iam.Role(this, 'SfnRole', {
  assumedBy: new iam.ServicePrincipal('states.amazonaws.com'),
});

new sfn.CfnStateMachine(this, 'Machine', {
  roleArn: role.roleArn,
  definitionString: cdk.Fn.sub(
    JSON.stringify({
      StartAt: 'Invoke',
      States: {
        Invoke: {
          Type: 'Task',
          Resource: 'arn:aws:states:::lambda:invoke',
          Parameters: { FunctionName: '${FnArn}' },
          End: true,
        },
      },
    }),
    { FnArn: fn.functionArn }
  ),
});

import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as sfn from 'aws-cdk-lib/aws-stepfunctions';
import * as tasks from 'aws-cdk-lib/aws-stepfunctions-tasks';

const fn = new lambda.Function(this, 'Fn', {
  runtime: lambda.Runtime.NODEJS_20_X,
  handler: 'index.handler',
  code: lambda.Code.fromInline('exports.handler = async () => {};'),
});

new sfn.StateMachine(this, 'Machine', {
  definitionBody: sfn.DefinitionBody.fromChainable(
    new tasks.LambdaInvoke(this, 'Invoke', { lambdaFunction: fn })
  ),
});

CDK Insights pinpoints the exact file and line in your CDK source for every finding, so you can jump straight to the fix.

Affected resource types

Intentional? Suppress this finding

Sometimes a flag is deliberate — a genuinely public endpoint, say. You can dismiss TL-PERM-005 and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "TL-PERM-005", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

Validations.of(scope).acknowledge({
  id: 'cdk-insights::TL-PERM-005',
  reason: 'Why this is intentional',
});

Use the rule ID TL-PERM-005 shown above — not the CDK-* ID from SARIF / GitHub code scanning. To dismiss every finding on one construct instead, use ignorePaths. Suppression docs →

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