AWS API Gateway with Lambda Integration

Goal

• Demonstrate how to integrate AWS Lambda with API Gateway

Pre-reqs

• AWS account and proper permissions through IAM

Build a Lambda function

• Log on AWS Web Console

• Services -> Lambda -> Create function

  • Function name: Lambda-API-Gateway-Demo
  • Runtime: Node.js 12.x
  • Permissions: Create a new role with basic Lambda permissions
  • Click Create function button

• Function code

  • Code entry type: Edit code inline (other options: Upload a .zip file; Upload from S3)
  • Runtime: Node.js 12.x
  • Handler: index.handler
  • index.js

  
  exports.handler = async (event) => {
    // TODO implement
    const response = {
        statusCode: 200,
        body: JSON.stringify('Hello from Lambda!'),
    };
    return response;
  };
  
  

Testing

• Configure test event

  • Create new test event
  • Event template: Hello World
  • Event name: LambdaDemo
  • Keep the rest as default
  • Click Test button to test
  • Log output

  
  {
    "statusCode": 200,
    "body": "\"Hello from Lambda!\""
  }
  
  

  
  START RequestId: 30020ce5-86be-47d1-ba61-ef08393f9dc7 Version: $LATEST
  END RequestId: 30020ce5-86be-47d1-ba61-ef08393f9dc7
  REPORT RequestId: 30020ce5-86be-47d1-ba61-ef08393f9dc7	Duration: 2.99 ms	Billed Duration: 100 ms	Memory Size: 128 MB	Max Memory Used: 64 MB	Init Duration: 423.93 ms
  
  

• Add trigger

  • Go to Designer UI of the function
  • Add trigger
    • Trigger configuration: API Gateway (other options: AWS IoT, Application Load Balancer, CloudWatch Events, CloudWatch Logs, DynamoDB, Kinesis, S3, SNS, SQS)
    • API: Create a new API
    • Security: Open (for testing purpose, not for production)
    • Click Add button
  • API Gateway looks like:

  
  Lambda-API-Gateway-Demo-API
  arn:aws-cn:execute-api:cn-northwest-1:005464510748:5uac1lg2va/*/*/Lambda-API-Gateway-Demo
  API: api-gateway/5uac1lg2va/*/*/Lambda-API-Gateway-DemoAPI endpoint: https://5uac1lg2va.execute-api.cn-northwest-1.amazonaws.com.cn/default/Lambda-API-Gateway-Demo API name: Lambda-API-Gateway-Demo-API
  
  

• Validate the integration

  • Open the link https://5uac1lg2va.execute-api.cn-northwest-1.amazonaws.com.cn/default/Lambda-API-Gateway-Demo on browser
    • “Hello from Lambda!” would be displayed

Conclusion

We achieved our goal successfully: AWS Lambda integration with API Gateway

• What we’ve done
  • Created Lambda function
  • Created API Gateway and added it as the Trigger of Lambda function
  • Validation