In this session, you’ll learn how to write AWS Lambda functions in Python to interact with S3 and DynamoDB. We will be utilising the SDK for Python, known as Boto3. With Boto3, developers can create, configure, and manage AWS services through code.

During this playground you will:

• Set up AWS Lambda to interact with other AWS services such as S3, DynamoDB, and CloudWatch
• Set up a trigger on S3 invoking the Lambda to take a CSV file and parse it to DynamoDB
• Configure permissions to allow the services to interact
• Utilise AWS CloudWatch

1. Creating the S3 Bucket

   S3 buckets are global and do not require a region. Each bucket name must be unique.

   • Navigate to S3
   • Click Create Bucket
   • Name Bucket
     • S3 is global. They need to be unique
     • Naming convection: "playground-s3-< your name >"
   • Block all public access
   • Create Bucket

   As you can see, the bucket is empty

2. Give Permissions-Role IAM roles needs lambda s3 permission and dynamnodb and cloudwatch logs

   • Navigate to IAM (Global region)
   • Click on Roles in left hand side
   • Click Create Role
   • Click Lambda Under Use Cases
   • Next Permissions
   • In the search Bar type in S3
   • Select Amazon S3 Full Access
   • In the search bar type in Dynamo
   • Select DynamoDBFullAccess
   • In the search bar type in CloudWatch
   • Select AWSOpsWorksCloudWatchLogs
   • Next Tags. This is good practice! Add tags
     • Name: < your name >
   • Name Role - "playground-role-< yourname >"

   Check to make sure all 3 policies are there

3. A Create Lambda Function

   • Navigate to Lambda
   • Click Create Function
   • Author From Scratch
   • Function name- "playground-lambda-< yourname >"
   • Python 3.8
   • Permissions
     • Use an existing role
     • Find your role (playground-role-< yourname >)
   • Create function

   Check out that confirmation!

   3.B Adding a Trigger

   This step enables the Lambda function to be triggered by the event of uploading an item into our S3 bucket

   • Design- Add Trigger
   • Search- S3
   • Bucket- Search for the S3 bucket you created
     • (playground-s3-< your name >)
   • Event Type- All
   • Suffix- .csv
   • Prefix- (optional)

Look for the confirmation. You can check the s3 details to make sure it is enabled.

4. Code to connect the Lambda function to the S3 bucket + testing our code

• Copy the code below into the code:

    import json
    import csv
    import boto3
  
    def lambda_handler(event, context):
        region = 'us-west-2'
        record_list = []
  
        try:
            s3 = boto3.client('s3')  
            bucket = event['Records'][0]['s3']['bucket']['name']
            key = event['Records'][0]['s3']['object']['key']
  
            print('\nBucket: ', bucket, 'Key: ',key)
  
        except Exception as e:
            print(str(e))
  
        return {
            'statusCode':200,
            'body': json.dumps('CSV to DynamoDB Success!')
        }
  

• Click Deploy

• Configure test event (upper right)

  • Event Template-Search 's3 put' (this shows the structure for the test)
  • Event name - "csv test"
  • Look for the S3 bucket
    • change bucket name to {name of bucket}
    • change object key to {name of file}
  • Create
  • Check the logs

• We can know look at CloudWatch to check the logs.

5. Triggering the Lambda with a S3 upload.

• First let's code some code to read through the rows and print the items out so we can see it in the logs.

    import json
    import csv
    import boto3
  
    def lambda_handler(event, context):
        region = 'us-east-2'
        record_list = []
  
        try:
            s3 = boto3.client('s3') 
            bucket = event['Records'][0]['s3']['bucket']['name']
            key = event['Records'][0]['s3']['object']['key']
  
            print('\nBucket: ', bucket, '\nKey:',key)
  
            csv_file = s3.get_object(Bucket = bucket, Key= key)
  
            record_list = csv_file['Body'].read().decode('utf-8').split('\n')
            
            csv_reader = csv.reader(record_list, delimiter=',',quotechar='"')
  
            for row in csv_reader:
                actor_id = row[0]
                firstname = row[1]
                surname = row[2]
                salary = row[3]
  
                print('\nActor_ID: ', actor_id, '\nFirst Name: ', firstname, '\nSurname: ', surname, '\nSalary: ', salary)
  
        except Exception as e:
            print(str(e))
  
        return {
            'statusCode':200,
            'body': json.dumps('CSV to DynamoDB Success!')
        }
  

• Deploy

• Nagivate to S3 and upload your file to the S3 bucket.

• Test

• Check the logs to make sure it works! You should see the contents of the file in the output.

6. Create the DynamoDB Table

   • Navigate to DynamoDB in a new tab. Important! Make sure you are in the same region as your Lambda Function.
   • Click Create table.
   • Enter  for the Table name.
   • Enter  for the Partition key and select  for the key type.
   • Add tags because it's good practice! name: jillian
   • Leave the Use default settings box checked and choose Create.
   • Click on the tabs on top just to check there are no items. After we upload, the items will appear here

7. Add code to connect the DynamoDB to the Lambda Function

        import json
        import csv
        import boto3
   
        def lambda_handler(event, context):
            region = 'us-east-2'
            record_list = []
   
            try:
                s3 = boto3.client('s3') 
   
                dynamodb = boto3.client('dynamodb', region_name = region)
   
                bucket = event['Records'][0]['s3']['bucket']['name']
                key = event['Records'][0]['s3']['object']['key']
   
                print('\nBucket: ', bucket, '\nKey:',key)
   
                csv_file = s3.get_object(Bucket = bucket, Key= key)
   
                record_list = csv_file['Body'].read().decode('utf-8').split('\n')
   
                
                csv_reader = csv.reader(record_list, delimiter=',',quotechar='"')
   
                for row in csv_reader:
                    actor_id = row[0]
                    firstname = row[1]
                    surname = row[2]
                    salary = row[3]
   
                    print('\nActor_ID: ', actor_id, '\nFirst Name: ', firstname, '\nSurname: ', surname, '\nSalary: ', salary)
   
                    add_to_db = dynamodb.put_item(
                        TableName = 'playground-db-jillian',
                        Item = {
                            'actor_id' : {'N':str(actor_id)},
                            'firstname' : {'S':str(firstname)},
                            'surname' : {'S':str(surname)},
                            'salary' : {'N':str(salary)},
                        })
                    print('\nSuccessfully added the records to the DynamoDB Table!\n')
   
            except Exception as e:
                print(str(e))
   
        return {
            'statusCode':200,
            'body': json.dumps('CSV to DynamoDB Success!')
        }
   

8. Check DynamoDB to make sure your items are there. You can also check out CLoudWatch and look through the logs.

This concludes our lab today!