Create Lambda function using AWS CloudShell

1. Access CloudShell from Lambda Console

Since npm is already installed in CloudShell, we can use it to create node_modules.

2. Create a lambda folder

mkdir lambda
cd lambda

3. Open Nano text editor

Run nano index.js to open the nano editing GNU.

// if no nano installed then run this first
sudo yum install -y nano
// else just run this
nano index.js

4. Copy the following code into the nano GNU

const AWSXRay = require('aws-xray-sdk-core');
const AWS = AWSXRay.captureAWS(require('aws-sdk'));
const s3 = new AWS.S3();
exports.handler = async function (event) {
  return s3.listBuckets().promise();
};

Then Ctrl-X, Y and Enter to exit nano.
We can run the following to double confirm the code has been pasted into index.js

cat index.js

5. Install the required Dependencies

npm i aws-xray-sdk

Run ll to check that node_modules exist and the dependencies are indeed being installed.

6. Set proper permission for files

chmod a+r *

7. Zip the files

zip -r function.zip .

Run ll again to double check zipped folder is created.

8. Create a IAM role

Since we are using lambda and S3, we need to assign 2 permission policies:

1. AWSLambdaBasicExecutionRole
2. AmazonS3ReadOnlyAccess

Name the IAM role as DemoLambdaRole

Copy the role ARN

9. Use cli to upload the zipped folder to create the lambda function

Remember to replace the ARN with yours

aws lambda create-function --zip-file fileb://function_test.zip --function-name lambda-with-dependencies --runtime nodejs14.x --handler index.handler --role arn:aws:iam::023028579192:role/DemoLambdaRole

Refresh the Lambda Functions table and you should see your new lambda being created

10. Enable x-ray Tracing

Lastly, since we are using x-ray, we also need to enable x-ray tracing at the lambda function.

Once you enabled x-ray tracing, go back to the IAM DemoLambdaRole and you will see a new permission policy being assigned.

11. Test the Lambda

You should see all your S3 buckets being returned, as shown below:

12. Clean up!

Finally, as a good habit, delete the Lambda to save resources. You may also delete the create Role too.

Cheers! Reference