# Granting an Amazon IoT rule the access it requires
Grant access

Use IAM roles to control the Amazon resources to which each rule has access. Before you create a rule, you must create an IAM role with a policy that allows access to the required Amazon resources. Amazon IoT assumes this role when implementing a rule.

**Complete the following steps to create the IAM role and Amazon IoT policy that grant an Amazon IoT rule the access it requires (Amazon CLI).**

1. Save the following trust policy document, which grants Amazon IoT permission to assume the role, to a file named `iot-role-trust.json`.  
****  

   ```
   {
       "Version":"2012-10-17",		 	 	 
       "Statement": [
           {
               "Effect": "Allow",
               "Principal": {
                   "Service": "iot.amazonaws.com"
           },
               "Action": "sts:AssumeRole",
               "Condition": {
                   "StringEquals": {
                       "aws:SourceAccount": "123456789012"
               },
                   "ArnLike": {
                       "aws:SourceArn": "arn:aws-cn:iot:us-east-1:123456789012:rule/rulename"
               }
           }
           }
       ]
   }
   ```

   Use the [create-role](https://docs.amazonaws.cn/cli/latest/reference/iam/create-role.html) command to create an IAM role specifying the `iot-role-trust.json` file:

   ```
   aws iam create-role --role-name my-iot-role --assume-role-policy-document file://iot-role-trust.json
   ```

   The output of this command looks like the following:

   ```
   {
   	"Role": {
   		"AssumeRolePolicyDocument": "url-encoded-json",
   		"RoleId": "AKIAIOSFODNN7EXAMPLE",
   		"CreateDate": "2015-09-30T18:43:32.821Z",
   		"RoleName": "my-iot-role",
   		"Path": "/",
   		"Arn": "arn:aws:iam::123456789012:role/my-iot-role"
   	}
   }
   ```

1. Save the following JSON into a file named `my-iot-policy.json`.  
****  

   ```
   {
   	"Version":"2012-10-17",		 	 	 
   	"Statement": [
   		{
   			"Effect": "Allow",
   			"Action": "dynamodb:*",
   			"Resource": "*"
   		}
   	]
   }
   ```

   This JSON is an example policy document that grants Amazon IoT administrator access to DynamoDB.

   Use the [create-policy](https://docs.amazonaws.cn/cli/latest/reference/iam/create-policy.html) command to grant Amazon IoT access to your Amazon resources upon assuming the role, passing in the `my-iot-policy.json` file:

   ```
   aws iam create-policy --policy-name my-iot-policy --policy-document file://my-iot-policy.json
   ```

   For more information about how to grant access to Amazon Web Services services in policies for Amazon IoT, see [Creating an Amazon IoT rule](iot-create-rule.md).

   The output of the [create-policy](https://docs.amazonaws.cn/cli/latest/reference/iam/create-policy.html) command contains the ARN of the policy. Attach the policy to a role.

   ```
   {
   	"Policy": {
   		"PolicyName": "my-iot-policy",
   		"CreateDate": "2015-09-30T19:31:18.620Z",
   		"AttachmentCount": 0,
   		"IsAttachable": true,
   		"PolicyId": "ZXR6A36LTYANPAI7NJ5UV",
   		"DefaultVersionId": "v1",
   		"Path": "/",
   		"Arn": "arn:aws:iam::123456789012:policy/my-iot-policy",
   		"UpdateDate": "2015-09-30T19:31:18.620Z"
   	}
   }
   ```

1. Use the [attach-role-policy](https://docs.amazonaws.cn/cli/latest/reference/iam/attach-role-policy.html) command to attach your policy to your role:

   ```
   aws iam attach-role-policy --role-name my-iot-role --policy-arn "arn:aws:iam::123456789012:policy/my-iot-policy"
   ```

## Revoke rule engine access


To immediately revoke rule engine access, do the following

1. Remove iot.amazonaws.com from the [trust policy](https://docs.aws.amazon.com/iot/latest/developerguide/iot-create-role.html)

1. Follow the steps to [revoke iot role sessions](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_use_revoke-sessions.html)