# Triggering AWS Lambda from Amazon SQS

- Learning material: ACloudGURU

## Diagram

## Introduce
In this hands-on AWS lab, we will learn how to trigger a Lambda function using SQS. This Lambda function will process messages from the SQS queue and insert the message data as records into a DynamoDB table.
## Steps
### Create the Lambda Function
- Add SQS as a trigger
- Modify the code

from datetime import datetime
import json
import os
import boto3

dynamodb = boto3.resource('dynamodb')

def lambda_handler(event, context):
    # Count items in the Lambda event 
    no_messages = str(len(event['Records']))
    print("Found " +no_messages +" messages to process.")

    for message in event['Records']:

        print(message)

        # Write message to DynamoDB
        table = dynamodb.Table('Message')

        response = table.put_item(
            Item={
                'MessageId': message['messageId'],
                'Body': message['body'],
                'Timestamp': datetime.now().isoformat()
            }
        )
        print("Wrote message to DynamoDB:", json.dumps(response))

### Log In to the EC2 Instance and Test the Script
- Switch user

su - cloud_user

- Execute the code in EC2 for sending messages to SQS

#!/usr/bin/env python3.8
# -*- coding: utf-8 -*-
import argparse
import logging
import sys
from time import sleep
import boto3
from faker import Faker


parser = argparse.ArgumentParser()
parser.add_argument("--queue-name", "-q", required=True,
                    help="SQS queue name")
parser.add_argument("--interval", "-i", required=True,
                    help="timer interval", type=float)
parser.add_argument("--message", "-m", help="message to send")
parser.add_argument("--log", "-l", default="INFO",
                    help="logging level")
args = parser.parse_args()

if args.log:
    logging.basicConfig(
        format='[%(levelname)s] %(message)s', level=args.log)

else:
    parser.print_help(sys.stderr)

sqs = boto3.client('sqs')

response = sqs.get_queue_url(QueueName=args.queue_name)

queue_url = response['QueueUrl']

logging.info(queue_url)

while True:
    message = args.message
    if not args.message:
        fake = Faker()
        message = fake.text()

    logging.info('Sending message: ' + message)

    response = sqs.send_message(
        QueueUrl=queue_url, MessageBody=message)

    logging.info('MessageId: ' + response['MessageId'])
    sleep(args.interval)

- Send 10 messages every second

 ./send_message.py -q Messages -i 0.1 


### Confirm Messages Were Inserted into the DynamoDB Table
- See the spike in SQS monitoring
- Check the table in DynamoDB
- Go to "Explore items" and choose the table you want for checking.