# aws-sns-lambda module
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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_lambda`|
| Typescript|`@aws-solutions-constructs/aws-sns-lambda`|
| Java|`software.amazon.awsconstructs.services.snslambda`|
## Overview
This AWS Solutions Construct implements an Amazon SNS connected to an AWS Lambda function.
Here is a minimal deployable pattern definition:
Typescript
```python
import { Construct } from 'constructs';
import { Stack, StackProps } from 'aws-cdk-lib';
import { SnsToLambda, SnsToLambdaProps } from "@aws-solutions-constructs/aws-sns-lambda";
import * as lambda from 'aws-cdk-lib/aws-lambda';
new SnsToLambda(this, 'test-sns-lambda', {
lambdaFunctionProps: {
runtime: lambda.Runtime.NODEJS_16_X,
handler: 'index.handler',
code: lambda.Code.fromAsset(`lambda`)
}
});
```
Python
```python
from aws_solutions_constructs.aws_sns_lambda import SnsToLambda
from aws_cdk import (
aws_lambda as _lambda,
Stack
)
from constructs import Construct
SnsToLambda(self, 'test_sns_lambda',
lambda_function_props=_lambda.FunctionProps(
code=_lambda.Code.from_asset('lambda'),
runtime=_lambda.Runtime.PYTHON_3_9,
handler='index.handler'
)
)
```
Java
```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.awsconstructs.services.snslambda.*;
new SnsToLambda(this, "test-lambda-sqs-stack", new SnsToLambdaProps.Builder()
.lambdaFunctionProps(new FunctionProps.Builder()
.runtime(Runtime.NODEJS_16_X)
.code(Code.fromAsset("lambda"))
.handler("index.handler")
.build())
.build());
```
## Pattern Construct Props
| **Name** | **Type** | **Description** |
|:-------------|:----------------|-----------------|
|existingLambdaObj?|[`lambda.Function`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_lambda.Function.html)|Existing instance of Lambda Function object, providing both this and `lambdaFunctionProps` will cause an error.|
|lambdaFunctionProps?|[`lambda.FunctionProps`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_lambda.FunctionProps.html)|User provided props to override the default props for the Lambda function.|
|existingTopicObj?|[`sns.Topic`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_lambda.Function.html)|Existing instance of SNS Topic object, 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.|
|enableEncryptionWithCustomerManagedKey?|`boolean`|If no key is provided, this flag determines whether the SNS Topic is encrypted with a new CMK or an AWS managed key. This flag is ignored if any of the following are defined: topicProps.masterKey, 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 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 SNS Topic with.|
## Pattern Properties
| **Name** | **Type** | **Description** |
|:-------------|:----------------|-----------------|
|lambdaFunction|[`lambda.Function`](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_lambda.Function.html)|Returns an instance of the Lambda function created by the pattern.|
|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.|
## 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 AWS managed KMS Key
* Enforce encryption of data in transit
### 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
* AWS_NODEJS_CONNECTION_REUSE_ENABLED (for Node 10.x and higher functions)
## Architecture

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