Setting Up Lambda Functions with S3 Event Triggers

1. Change to the directory where the necessary files are located:

   cd exercise_files/Section4-AppLayer/Lab1-LambdaS3EventTrigger/
   

2. Create an IAM role for Lambda using the AWS IAM CLI command:

   aws iam create-role --role-name LambdaIAMRole --description "Lambda Role" --assume-role-policy-document file://lambda_assume_role_policy.json
   

3. In the output under "Arn", copy the role ARN and paste it into a text file for later use.

1. Create an IAM policy:

   aws iam create-policy --policy-name LambdaRolePolicy --policy-document file://lambda_execution_policy.json
   

2. In the output under "Arn", copy the policy ARN for use in the next set of commands.

3. Attach the policy to the role, replacing <POLICY_ARN> with the ARN previously copied:

   aws iam attach-role-policy --role-name "LambdaIAMRole" --policy-arn <POLICY_ARN>
   

1. Create an SNS topic:

   aws sns create-topic --name LambdaTopic --region us-east-1
   

2. In the output under "TopicArn", copy the topic ARN for use in the next set of commands.

3. Subscribe an endpoint (e.g., email address) to your topic, replacing <TOPIC_ARN> with the previously copied ARN and <EMAIL_ADDRESS> with your own email:

   aws sns subscribe --protocol "email" --topic-arn <TOPIC_ARN> --notification-endpoint <EMAIL_ADDRESS> --region us-east-1
   

   You should receive the status message "SubscriptionArn": "pending confirmation".

4. To confirm the subscription, access the email previously used, open the SNS email, and click click Confirm subscription.

1. Open the lambda_function.py file:

   vim lambda_function.py
   

2. To enable sending SNS notifications, uncomment the line client = boto3.client('sns') and the section below:

   response = client.publish(
   TopicArn='<SNS-TOPIC-ARN>',
   Message= payload_str,
   Subject='My Lambda S3 event')
   

3. In TopicArn, replace with the topic ARN previously copied.

4. To save and exit the file, press ESC, type :wq, and press Enter.

5. Zip the file into a deployment package:

   zip lambda_function.zip lambda_function.py
   

1. Create a Lambda function, replacing <ROLE_ARN> with the role ARN previously copied:

aws lambda create-function --memory-size 128 --function-name my-lambda --runtime python3.7 --handler lambda_function.lambda_handler --zip-file fileb://lambda_function.zip --role <ROLE_ARN>

1. In the output under "FunctionArn", copy the function ARN to a text file for later use.

1. Add Lambda permission, replacing <ARN_S3_BUCKET> with the ARN of the S3 bucket provided on the lab credentials page:

aws lambda add-permission --action lambda:InvokeFunction --principal s3.amazonaws.com --statement-id LabS3Trigger --function-name my-lambda --source-arn "<ARN_S3_BUCKET>"

1. Open the bucket-trigger-notification.json file:

   vim bucket-trigger-notification.json
   

2. In the output under "LambdaFunctionArn", delete the existing text and replace it with the function ARN previously copied into a text file:

   "LambdaFunctionArn": "<FUNCTION_ARN>"
   

3. To save and exit the file, press ESC, type :wq, and press Enter.

4. Enable the notification configuration on the S3 website bucket, replacing <S3_BUCKET_NAME> with the bucket name provided on the lab credentials page:

   aws s3api put-bucket-notification-configuration --bucket <S3_BUCKET_NAME> --notification-configuration file://bucket-trigger-notification.json

1. Upload a file to the bucket, replacing <S3_BUCKET_NAME> with the bucket name provided on the lab credentials page:

   aws s3 cp lambda_function.py s3://<S3_BUCKET_NAME>
   

2. Once successfully uploaded, check your email.

   You should receive a notification email with details of the file uploaded to the S3 bucket.