# aws-sns-sqs module
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> All classes are under active development and subject to non-backward compatible changes or removal in any
> future version. These are not subject to the [Semantic Versioning](https://semver.org/) model.
> This means that while you may use them, you may need to update your source code when upgrading to a newer version of this package.
---
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| **Reference Documentation**:| <span style="font-weight: normal">https://docs.aws.amazon.com/solutions/latest/constructs/</span>|
|:-------------|:-------------|
<div style="height:8px"></div>
| **Language** | **Package** |
|:-------------|-----------------|
| Python|`aws_solutions_constructs.aws_sns_sqs`|
| Typescript|`@aws-solutions-constructs/aws-sns-sqs`|
| Java|`software.amazon.awsconstructs.services.snssqs`|
## Overview
This AWS Solutions Construct implements an Amazon SNS topic connected to an Amazon SQS queue.
Here is a minimal deployable pattern definition:
Typescript
```python
import { Construct } from 'constructs';
import { Stack, StackProps } from 'aws-cdk-lib';
import { SnsToSqs, SnsToSqsProps } from "@aws-solutions-constructs/aws-sns-sqs";
import * as iam from 'aws-cdk-lib/aws-iam';
const snsToSqsStack = new SnsToSqs(this, 'SnsToSqsPattern', {});
// Grant yourself permissions to use the Customer Managed KMS Key
const policyStatement = new iam.PolicyStatement({
actions: ["kms:Encrypt", "kms:Decrypt"],
effect: iam.Effect.ALLOW,
principals: [ new iam.AccountRootPrincipal() ],
resources: [ "*" ]
});
snsToSqsStack.encryptionKey?.addToResourcePolicy(policyStatement);
```
Python
```python
from aws_solutions_constructs.aws_sns_sqs import SnsToSqs
from aws_cdk import (
aws_iam as iam,
Stack
)
from constructs import Construct
construct_stack = SnsToSqs(self, 'SnsToSqsPattern')
policy_statement = iam.PolicyStatement(
actions=["kms:Encrypt", "kms:Decrypt"],
effect=iam.Effect.ALLOW,
principals=[iam.AccountRootPrincipal()],
resources=["*"]
)
construct_stack.encryption_key.add_to_resource_policy(policy_statement)
```
Java
```java
import software.constructs.Construct;
import java.util.List;
import software.amazon.awscdk.Stack;
import software.amazon.awscdk.StackProps;
import software.amazon.awscdk.services.iam.*;
import software.amazon.awsconstructs.services.snssqs.*;
final SnsToSqs constructStack = new SnsToSqs(this, "SnsToSqsPattern",
new SnsToSqsProps.Builder()
.build());
// Grant yourself permissions to use the Customer Managed KMS Key
final PolicyStatement policyStatement = PolicyStatement.Builder.create()
.actions(List.of("kms:Encrypt", "kms:Decrypt"))
.effect(Effect.ALLOW)
.principals(List.of(new AccountRootPrincipal()))
.resources(List.of("*"))
.build();
constructStack.getEncryptionKey().addToResourcePolicy(policyStatement);
```
## Pattern Construct Props
| **Name** | **Type** | **Description** |
|:-------------|:----------------|-----------------|
|existingTopicObj?|[`sns.Topic`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sns.Topic.html)|An optional, existing SNS topic to be used instead of the default topic. Providing both this and `topicProps` will cause an error.|
|topicProps?|[`sns.TopicProps`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sns.TopicProps.html)|Optional user provided properties to override the default properties for the SNS topic.|
|existingQueueObj?|[`sqs.Queue`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sqs.Queue.html)|An optional, existing SQS queue to be used instead of the default queue. Providing both this and `queueProps` will cause an error.|
|queueProps?|[`sqs.QueueProps`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sqs.QueueProps.html)|Optional user provided properties to override the default properties for the SQS queue.|
|deployDeadLetterQueue?|`boolean`|Whether to create a secondary queue to be used as a dead letter queue. Defaults to true.|
|deadLetterQueueProps?|[`sqs.QueueProps`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sqs.QueueProps.html)|Optional user-provided props to override the default props for the dead letter SQS queue.|
|maxReceiveCount?|`number`|The number of times a message can be unsuccessfully dequeued before being moved to the dead letter queue. Defaults to 15.|
|enableEncryptionWithCustomerManagedKey?|`boolean`|If no key is provided, this flag determines whether the queue is encrypted with a new CMK or an AWS managed key. This flag is ignored if any of the following are defined: topicProps.masterKey, queueProps.encryptionMasterKey, encryptionKey or encryptionKeyProps.|
|encryptionKey?|[`kms.Key`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_kms.Key.html)|An optional, imported encryption key to encrypt the SQS Queue and SNS Topic with.|
|encryptionKeyProps?|[`kms.KeyProps`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_kms.Key.html#construct-props)|Optional user provided properties to override the default properties for the KMS encryption key used to encrypt the SQS queue with.|
|sqsSubscriptionProps?|[`subscriptions.SqsSubscriptionProps`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sns_subscriptions.SqsSubscriptionProps.html)|Optional user-provided props to override the default props for sqsSubscriptionProps.|
## Pattern Properties
| **Name** | **Type** | **Description** |
|:-------------|:----------------|-----------------|
|snsTopic|[`sns.Topic`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sns.Topic.html)|Returns an instance of the SNS topic created by the pattern.|
|encryptionKey|[`kms.Key`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_kms.Key.html)|Returns an instance of kms.Key used for the SQS queue, and SNS Topic.|
|sqsQueue|[`sqs.Queue`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sqs.Queue.html)|Returns an instance of the SQS queue created by the pattern.|
|deadLetterQueue?|[`sqs.Queue`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sqs.Queue.html)|Returns an instance of the dead-letter SQS queue created by the pattern.|
## Default settings
Out of the box implementation of the Construct without any override will set the following defaults:
### Amazon SNS Topic
* Configure least privilege access permissions for SNS Topic
* Enable server-side encryption for SNS Topic using Customer managed KMS Key
* Enforce encryption of data in transit
### Amazon SQS Queue
* Configure least privilege access permissions for SQS Queue
* Deploy SQS dead-letter queue for the source SQS Queue
* Enable server-side encryption for SQS Queue using Customer managed KMS Key
* Enforce encryption of data in transit
## Architecture

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