This thread discusses the steps to deploy a Lambda function named "getIdentities" with a layer and expose it through API Gateway using AWS SAM. The Lambda function fetches data from DynamoDB, you can use the following AWS SAM template. This example assumes you're working with Node.js for your Lambda function and DynamoDB as your database:
YAML
AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Resources:
MyLambdaLayer:
Type: AWS::Serverless::LayerVersion
Properties:
LayerName: MyLayer
ContentUri: ./layer/
CompatibleRuntimes:
- nodejs14.x
Description: My Lambda Layer
MyLambdaFunction:
Type: AWS::Serverless::Function
Properties:
Handler: index.handler
Runtime: nodejs14.x
Layers:
- !Ref MyLambdaLayer
CodeUri: ./function/
Description: My Lambda Function
Environment:
Variables:
DYNAMODB_TABLE_NAME: !Ref MyDynamoDBTable
Events:
MyApi:
Type: Api
Properties:
Path: /getIdentities
Method: GET
MyDynamoDBTable:
Type: AWS::DynamoDB::Table
Properties:
TableName: MyDynamoDBTable
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: 5
WriteCapacityUnits: 5
Outputs:
MyApi:
Description: "API Gateway endpoint URL"
Value:
Fn::Sub: "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/getIdentities"
In this SAM template:
1. We define a Lambda Layer resource named `MyLambdaLayer`. You should place your layer code in the `./layer/` directory.
2. We define a Lambda function resource named `MyLambdaFunction`. This function uses the layer created in step 1 and is associated with an API Gateway event at the path "/getIdentities" and HTTP method GET. The function code is located in the `./function/` directory, and the handler is set to `index.handler`. We also set an environment variable to specify the DynamoDB table name.
3. We define a DynamoDB table resource named `MyDynamoDBTable` to store your data. Adjust the table name, schema, and provisioned throughput according to your requirements.
4. The Outputs section provides the URL of the API Gateway endpoint where you can invoke the "getIdentities" Lambda function.
Make sure your project directory structure is organized as follows:
project-directory/
├── template.yaml
├── function/
│ ├── index.js
│ └── package.json
├── layer/
│ ├── layer-files
└── template-configs/
├── parameters.json
├── metadata.json
To fetch data from DynamoDB, you can use the AWS SDK for JavaScript in your Lambda function code. Here's a simple example of how you can fetch data from DynamoDB using the Node.js SDK:
const AWS = require('aws-sdk');
const dynamodb = new AWS.DynamoDB.DocumentClient();
const tableName = process.env.DYNAMODB_TABLE_NAME;
exports.handler = async (event) => {
try {
const params = {
TableName: tableName,
Key: {
id: 'your-key-here',
},
};
const data = await dynamodb.get(params).promise();
return {
statusCode: 200,
body: JSON.stringify(data.Item),
};
} catch (error) {
return {
statusCode: 500,
body: JSON.stringify({ error: error.message }),
};
}
};
In this code, we're using the AWS SDK to fetch an item from DynamoDB based on a specified key. You should customize the key and error handling based on your use case.
