Free tool

IoT Core rule action role policy generator

Pick the services your IoT Core calls and get the rule action role it needs — scoped to the right ARNs, with the reason behind every action.

1. Which thing needs the role?

The compute that makes the calls. It assumes the role; everything else is a resource the role points at.

Principal

Changing this opens that principal’s own page.

2. What does it call?

Only connections the knowledge base records IAM requirements for. Tick what your IoT Core actually talks to.

DynamoDBA topic rule's DynamoDB action writes the (optionally transformed) device message straight into a table — e.g. persisting each sensor reading as an item, keyed by device ID and timestamp
LambdaA topic rule's Lambda action invokes a function with the matched device message as input — the general-purpose way to run custom logic on incoming device data
S3A topic rule's S3 action saves the message payload as an object — e.g. archiving raw device data to a bucket for later batch processing or as a data lake landing zone
SNSA topic rule's SNS action publishes to a topic to fan a device event out to multiple subscribers or send a push/SMS notification — e.g. alerting when a sensor crosses a threshold
SQSA topic rule's SQS action sends the message to a queue, giving a downstream consumer a durable buffer to process device data at its own pace
Step FunctionsA topic rule's Step Functions action starts a state machine execution from a device message — kicking off a multi-step workflow (e.g. an over-the-air update or an incident-response flow) in response to a device event

3. Fill in your account (optional)

Leave these blank and the ARNs keep visible placeholders, so a half-finished policy fails instead of quietly granting more than you meant.

Region

Account ID

Role name

Your role

Nothing selected yet, so the role below can be assumed but grants nothing. Tick a service above.

identity-policy.json

{
  "Version": "2012-10-17",
  "Statement": []
}

trust-policy.json

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "IoTCoreAssumeRole",
      "Effect": "Allow",
      "Principal": {
        "Service": "iot.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}

Before you apply this

These are the actions this integration typically needs — not a least-privilege proof. After you deploy, narrow the policy with IAM Access Analyzer, which generates one from the calls the principal actually made.
No permissions were generated. The role below can be assumed but grants nothing — pick at least one service this principal calls.

Worth knowing about a IoT Core rule action role

This role is assumed by an IoT topic rule to run its action. Each rule action names the role it uses, so a rule fanning out to several targets can share one role or use one per action.
The trust policy lets any iot.amazonaws.com resource in any account assume this role. AWS recommends narrowing it with an aws:SourceArn (and aws:SourceAccount) condition naming the specific resource that may assume it — add that once you know the ARN.

Grounded in the same data that validates diagrams

Design Beaver models AWS connections so it can tell you when a diagram is wrong. Part of that model is which IAM actions each integration needs and why — researched against AWS documentation, not inferred. This tool reads that data directly, which is why it can explain every statement instead of just emitting one.

It also means the tool knows what it doesn’t know. A connection the knowledge base has no IAM data for is skipped and named, never filled in with a plausible guess. Where an action comes from somewhere other than the knowledge base, it is labelled.

What a IoT Core rule action role can be scoped to

IoT Core assumes this role through the iot.amazonaws.com service principal. These are the 6 connections the knowledge base records IAM requirements for:

IoT Core → DynamoDB

A topic rule's DynamoDB action writes the (optionally transformed) device message straight into a table — e.g. persisting each sensor reading as an item, keyed by device ID and timestamp

dynamodb:PutItem

The rule's IAM role must grant dynamodb:PutItem on the target table

IoT Core → Lambda

A topic rule's Lambda action invokes a function with the matched device message as input — the general-purpose way to run custom logic on incoming device data

lambda:InvokeFunction

The rule's IAM role (the role IoT Core assumes to run the action) must grant lambda:InvokeFunction on the target function

IoT Core → S3

A topic rule's S3 action saves the message payload as an object — e.g. archiving raw device data to a bucket for later batch processing or as a data lake landing zone

s3:PutObject

The rule's IAM role must grant s3:PutObject on the target bucket/prefix

IoT Core → SNS

A topic rule's SNS action publishes to a topic to fan a device event out to multiple subscribers or send a push/SMS notification — e.g. alerting when a sensor crosses a threshold

sns:Publish

The rule's IAM role must grant sns:Publish on the target topic

IoT Core → SQS

A topic rule's SQS action sends the message to a queue, giving a downstream consumer a durable buffer to process device data at its own pace

sqs:SendMessage

The rule's IAM role must grant sqs:SendMessage on the target queue

IoT Core → Step Functions

A topic rule's Step Functions action starts a state machine execution from a device message — kicking off a multi-step workflow (e.g. an over-the-air update or an incident-response flow) in response to a device event

states:StartExecution

The rule's IAM role must grant states:StartExecution on the target state machine

Generate a role for something else

Questions

Where do the actions come from?

From Design Beaver's AWS knowledge base — the same data its validation engine uses to check architecture diagrams. Each connection between two services records the IAM actions that integration needs and the reason it needs them, researched against AWS documentation. Nothing is generated by a model, and the tool refuses to guess: a service pair the knowledge base has no IAM data for is skipped and reported rather than invented.

Is this a least-privilege policy?

No, and it says so on every policy it generates. These are the actions the integration typically needs — a sound starting point, not proof of minimum access. After you deploy, narrow it with IAM Access Analyzer, which generates a policy from the calls the principal actually made. That is the only way to get a genuinely least-privilege result.

How is this different from the other IAM policy generators?

Most of them start from the action catalogue: search 20,000 actions across 400 services and pick the ones you want, which assumes you already know the answer. This one starts from the architecture — this Lambda calls DynamoDB and SQS — and works out the actions from there. It also scopes each statement to the right ARN, so s3:ListBucket lands on the bucket while s3:GetObject lands on the objects inside it.

Does anything I type leave my browser?

No. The generator runs entirely client-side. Bucket names, table names, account IDs and ARNs are never sent anywhere, and there is no signup.

Why are there two policies?

AWS needs both. The trust policy says who may assume the role — the service principal, like lambda.amazonaws.com. The identity policy says what the role may then do. A role with permissions but no trust policy cannot be assumed by anything, and a role with trust but no permissions can be assumed but does nothing.

Draw it instead, and the role attaches itself

Design Beaver knows which connections need a role because it checks them as you draw. Drop an IAM Role node onto a function and the warnings it resolves disappear. Free, in your browser — sign in with Google or GitHub to save your work.

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