Automating EC2 Start & Stop Using AWS Lambda, EventBridge & CloudWatch (Beginner DevOps Guide)

🚀 Automating EC2 Start & Stop Using AWS Lambda, EventBridge & CloudWatch (Beginner-Friendly DevOps Guide)

Cloud costs can quickly increase if EC2 instances run 24/7. What if you could automatically start and stop your EC2 instances based on a schedule — without managing servers?

In this blog, we’ll explore:

1. What serverless really means

2. AWS services involved

3. Step-by-step EC2 automation architecture

4. Lambda code example

5. DevOps and cost optimization benefits

This guide is beginner-friendly and SEO-optimized for learners exploring AWS, DevOps, and Serverless Architecture.

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🌩️ What Is Serverless?

Serverless is a cloud computing model where:

1. You don’t provision or manage servers

2. You deploy code as functions

3. Scaling is automatic

4. You pay only for usage

Initially, serverless was known as FaaS (Function as a Service), pioneered by:

• AWS Lambda

But today, serverless also includes managed services like:

1. Databases

2. Messaging systems

3. Storage

4. Containers

⚠️ Important:
Serverless does NOT mean “no servers.”
It means you don’t manage them.

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🧠 AWS Serverless Services Used in This Project

1️⃣ AWS Lambda

AWS Lambda is:

1. Event-driven compute service

2. Pay-as-you-go

3. Auto-scaling

4. No server management

You upload your function code, and AWS runs it when triggered.

You’re charged based on:

1. Number of requests

2. Execution time

Perfect for automation tasks like:

1. Starting EC2 instances

2. Stopping EC2 instances

3. Cleaning S3 buckets

4. Sending alerts

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2️⃣ Amazon EventBridge

Amazon EventBridge is a serverless event bus that connects AWS services and SaaS applications.

Key Features:

1. Supports cron and rate expressions

2. Routes events to Lambda, EC2, ECS, CodeBuild

3. Enables event-driven architecture

4. No custom polling required

In this project:

👉 EventBridge triggers Lambda every 5 minutes
👉 Lambda starts or stops EC2 instances

Example Cron Expression

cron(0 12 * * ? *)

This runs every day at 12:00 PM (UTC).

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3️⃣ Amazon CloudWatch

Amazon CloudWatch monitors:

1. EC2 instances

2. Lambda logs

3. RDS databases

4. Application metrics

CloudWatch helps in:

1. Viewing Lambda execution logs

2. Monitoring failures

3. Creating dashboards

4. Setting alarms

It integrates with:

1. Amazon SNS

2. EC2 Auto Scaling

3. CloudTrail

4. IAM

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🏗️ Architecture: Automating EC2 Start & Stop

Here’s how the automation works:

1️⃣ EventBridge rule triggers on schedule
2️⃣ Lambda function executes
3️⃣ Lambda calls EC2 API
4️⃣ EC2 instance starts or stops
5️⃣ Logs are stored in CloudWatch

This creates a fully automated, serverless cost-optimization solution.

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💻 Lambda Code Example (Start EC2)

import boto3

region = 'ap-south-1'
instances = ['i-06a14086f3b314a40']

ec2 = boto3.client('ec2', region_name=region)

def lambda_handler(event, context):
    ec2.start_instances(InstanceIds=instances)
    print('Starting your instances: ' + str(instances))

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💻 Lambda Code Example (Stop EC2)

import boto3

region = 'ap-south-1'
instances = ['i-06a14086f3b314a40']

ec2 = boto3.client('ec2', region_name=region)

def lambda_handler(event, context):
    ec2.stop_instances(InstanceIds=instances)
    print('Stopping your instances: ' + str(instances))

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🔐 Required IAM Permissions

Your Lambda function needs permissions to:

1. ec2:StartInstances

2. ec2:StopInstances

3. ec2:DescribeInstances

Always follow the principle of least privilege.

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💰 Why Automate EC2 Start & Stop?

Many companies run development servers only during business hours.

Example:

1. Start: 9 AM

2. Stop: 6 PM

This reduces costs significantly.

Benefits:

✔ Saves cloud cost
✔ No manual intervention
✔ Improves DevOps efficiency
✔ Scales automatically
✔ Beginner-friendly project

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🔄 EventBridge Rule Setup

You can create two rules:

Rule 1 – Start EC2

1. Schedule: cron expression

2. Target: Lambda (Start function)

Rule 2 – Stop EC2

1. Schedule: cron expression

2. Target: Lambda (Stop function)

You can also use:

rate(5 minutes)

for recurring triggers.

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📊 Monitoring with CloudWatch Logs

After execution:

1. Go to CloudWatch

2. Open Log Groups

3. Select your Lambda function

4. View execution logs

This helps in debugging errors and performance tuning.

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🧩 Real-World DevOps Learning

This project helps you understand:

1. Serverless architecture

2. Event-driven systems

3. Infrastructure automation

4. Cloud cost optimization

5. IAM security best practices

It’s an excellent beginner DevOps project for:

1. Students

2. Cloud learners

3. Interview preparation

4. Resume building

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🌍 Where This Is Used in Industry

Companies use similar automation for:

1. Dev/Test environments

2. Non-production servers

3. Temporary workloads

4. Scheduled batch systems

This is real-world cloud engineering practice.

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🚀 Final Thoughts

Serverless is transforming DevOps.

By combining:

1. AWS Lambda

2. EventBridge

3. CloudWatch

You can build scalable automation without managing infrastructure.

If you're learning AWS and DevOps, this project is a must-try.

Start small. Automate smart. Optimize costs.

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💬 If you enjoyed this blog, stay connected for more hands-on cloud and DevOps tutorials.

See you in the next one!