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Simple Lambda Function

Updated Jan 08, 2025 ·

Pre-requisites​

  • An AWS account
  • A Github account

Create the Lambda Function​

Login to your AWS account and go to Lambda then Create Function.

In the Create function page, enter the details below. Once done, click the Create function at the bottom.

You should now see the Function overview and the Code source sections.

Testing the Function​

We can test the Lambda function directly by clicking the Test button then select Create new test event.

Enter the test name and under Template, click the dropdown bar and select APPI Gateway AWS Proxy.

Click Save and then Invoke.

You should see the complete response and logs:

Status: Succeeded
Test Event Name: (unsaved) test event

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

Function Logs:
START RequestId: 3ab4d326-d4eb-413e-ab2a-859370555567 Version: $LATEST
END RequestId: 3ab4d326-d4eb-413e-ab2a-859370555567
REPORT RequestId: 3ab4d326-d4eb-413e-ab2a-859370555567	Duration: 13.35 ms	Billed Duration: 14 ms	Memory Size: 128 MB	Max Memory Used: 68 MB	Init Duration: 175.55 ms

Request ID: 3ab4d326-d4eb-413e-ab2a-859370555567

Adding Changes to the Code​

Modify the code by printing out the event.

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

Whenever you make changes to the code, you need to Save and Deploy. It will commonly be set to Auto Save, but to check, you can click the menu button > Auto Save

You will also a message at the left: "You have undeployed changes". Click the Deploy button then click the Invoke once again.

It will return more details in the output response:

Status: Succeeded
Test Event Name: (unsaved) test event

Response:
{
  "statusCode": 200,
  "body": "\"Hello from Lambda!\"",
  "event": 
  {
    "body": "eyJ0ZXN0IjoiYm9keSJ9",
    "resource": "/{proxy+}",
    "path": "/path/to/resource",
    "httpMethod": "POST",
    "isBase64Encoded": true,
    "queryStringParameters": {
      "foo": "bar"
    },
    "multiValueQueryStringParameters": {
      "foo": [
        "bar"
      ]
    },
    "pathParameters": {
      "proxy": "/path/to/resource"
    },
    "stageVariables": {
      "baz": "qux"
    }
}

....

Function Logs:
START RequestId: c6c8cfb6-afdc-4b46-ac4a-f4cad9c87a96 Version: $LATEST
END RequestId: c6c8cfb6-afdc-4b46-ac4a-f4cad9c87a96
REPORT RequestId: c6c8cfb6-afdc-4b46-ac4a-f4cad9c87a96	Duration: 103.55 ms	Billed Duration: 104 ms	Memory Size: 128 MB	Max Memory Used: 68 MB

Request ID: c6c8cfb6-afdc-4b46-ac4a-f4cad9c87a96

Monitoring the Function​

Click the Monitor tab to see the metrics of your Lambda function.

Click View CloudWatch logs.

Select the latest log stream to view log events.

You can click each event for more details.

Deleting the Function​

To delete the function, click Actions then