🚀 AWS Beginner Tutorial — Build Serverless Apps with Lambda, CloudWatch, API Gateway, S3 & EventBridge Review

Whether you’re diving into serverless for the first time or just brushing up on your AWS skills, Digital Cloud Training’s AWS serverless guide walks you through a complete project using AWS Lambda, CloudWatch Logs, API Gateway, S3 static hosting, DynamoDB, and EventBridge. This is my interpretation of the guide in a more textual format for those completely new to AWS.

All source has been sourced and used from Digital Cloud Training’s GitHub repo.

✅ Part 1 — Logging to AWS CloudWatch with Python in Lambda

🛠 Step 1: Create the Lambda Function

From the AWS Console, navigate to:
Lambda > Functions > Create function

Name: WriteToCloudWatch

Runtime: Python 3.13

Architecture: x86_64

Permissions: Let AWS create a new role with basic Lambda permissions.

✅ Step 2: Confirm Creation

After clicking Create function, AWS shows a success banner.

💻 Step 3: Add Logging Code in Python

Paste this into the inline code editor:

import logging
import json
logger = logging.getLogger()
logger.setLevel(logging.INFO)
def lambda_handler(event, context):
    message = event.get('message', 'No message provided')
    logger.info(message)
    return {
        'statusCode': 200,
        'body': json.dumps('Message logged successfully!')
    }

Click Deploy to apply changes.

🧪 Step 4: Create a Test Event

Use this JSON payload to simulate a message:

{
  "message": "Hello, CloudWatch!"
}

Click Test and confirm successful execution in the Log output.

🔍 Step 5: Inspect Logs

Under the Monitor tab, click View CloudWatch Logs to see your message alongside Lambda execution metadata.

💡 Bonus: Invoke via AWS CLI

In CloudShell, save the payload:

{
  "message": "Hello from CLI!"
}

Then run:

aws lambda invoke --function-name WriteToCloudWatch --payload fileb://payload.json response.json

Confirm in both response.json and CloudWatch logs that the message logged successfully.

🔁 Part 2 — Triggering Lambda with S3 Uploads

🧠 Upgrade Lambda to Handle S3 Events

Update your function to log file uploads:

import json
import logging
logger = logging.getLogger()
logger.setLevel(logging.INFO)
def lambda_handler(event, context):
    logger.info("Event: " + json.dumps(event))
    for record in event['Records']:
        bucket_name = record['s3']['bucket']['name']
        file_key = record['s3']['object']['key']
        logger.info(f"New file uploaded: {file_key} in bucket {bucket_name}")
    return {
        'statusCode': 200,
        'body': json.dumps('S3 event processed!')
    }

🔒 IAM Permissions: CloudWatch & S3

Ensure the role attached to Lambda has policies for:

logs:CreateLogGroup, logs:CreateLogStream, logs:PutLogEventsAmazonS3ReadOnlyAccess

🧲 Add S3 Trigger

On your target bucket (e.g., exampleBucket), set a trigger for All object create events linked to WriteToCloudWatch.

✅ Confirm Setup

Upload a file to the bucket. Check logs in CloudWatch for confirmation that the filename and bucket name were captured.

🌐 Part 3 — API Gateway + Lambda + DynamoDB + S3 Frontend

🔌 REST API Setup

API Gateway > Create REST API

New API name: ProductOrdersAPI

Endpoint type: Regional

Create resource path /orders

Enable CORS

Add POST method (triggers SubmitOrderFunction)

Enable Lambda Proxy Integration

🚀 Deploy API

Deploy to a new stage prod.

Final endpoint:

https://example-api.us-east-1.amazonaws.com/prod/orders

💻 S3 Static Website Hosting

Create bucket: myexamplebucket

Disable ACLs; allow public access

Enable static website hosting

Index document: index.html

Apply public-read bucket policy

Upload index.html

Website URL:

http://myexampleapistaticwebsite-zzzz.s3-website-us-east-1.amazonaws.com

🧪 Live Integration Test

Use the form to submit an order (e.g., iPad, Quantity: 1).

Confirm:

API Gateway logs success

DynamoDB ProductOrders table stores entry

CloudWatch logs capture execution

🔄 Part 4 — Automate EC2 Events with EventBridge

🪧 Step 1: Define EventBridge Rule

Go to EventBridge > Create Rule

Name: stopec2

Event bus: default

Rule type: Rule with event pattern

🔍 Step 2: Event Pattern for EC2 AMI State

Service: EC2

Event type: EC2 AMI State Change

Specific state: available

Example JSON:

{
  "source": ["aws.ec2"],
  "detail-type": ["EC2 AMI State Change"],
  "detail": {
    "State": ["available"]
  }
}

🎯 Step 3: Set Target to Lambda

Target: Lambda function

Function name: stopec2

Role: Let EventBridge create a new role

🔐 Step 4: Permissions

Ensure the Lambda’s execution role has AmazonEC2FullAccess.

✅ Step 5: Complete Rule

Review and click Create Rule. Now, your Lambda triggers when an AMI becomes available.

🧪 Test & Observe Logs

Manually register an AMI or publish a test event to validate. Confirm execution via CloudWatch Logs.

🧠 Why EventBridge?

Serverless: No polling, no cron jobs

Cheap: Triggers on events only

Powerful: Works with SNS, SQS, Step Functions, more

🧾 Final Summary: End-to-End AWS Automation

You’ve now built a complete, serverless AWS app with:

Lambda: Custom logic

CloudWatch: Observability

API Gateway: Client interface

DynamoDB: Persistent data

S3: Static frontend

EventBridge: Automation workflows