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Building a Secure Web Application on AWS: VPC, EC2, IAM, RDS and CloudWatch

Learn how to design and deploy a basic web application on AWS using VPC, EC2, RDS, IAM, and CloudWatch, while applying essential cloud security practices such as private networking, least-privilege access, and monitoring.

Jeeva J P

Cloud and Cyber Security Practitioner

Building a Secure Web Application on AWS

In my previous article, I introduced the fundamentals of cloud computing and key AWS services such as EC2, S3, RDS, Lambda, and VPC.
This time, let's see how these services can work together to build a simple web application with security in mind.

Basic Architecture

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Internet
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Load Balancer
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EC2 Instances
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RDS Database

AWS VPC
The main components are:
  • VPC — Provides an isolated network for AWS resources.
  • EC2 — Runs the application.
  • RDS — Stores application data.
  • Load Balancer — Distributes incoming traffic.
  • IAM — Controls access to AWS resources.
  • CloudWatch — Monitors applications and infrastructure.

1. VPC and Subnets

A VPC allows us to create our own network in AWS.
A simple design can separate resources into public and private subnets:
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VPC
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+-- Public Subnet
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| +-- Load Balancer
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+-- Private Subnet
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+-- EC2
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+-- RDS
The load balancer can receive internet traffic, while the application and database remain protected inside private networking where appropriate.

2. EC2 for the Application

Amazon EC2 provides the virtual server where our application can run.
For example:
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User
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v
Load Balancer
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EC2
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v
Application
Multiple EC2 instances can be used when higher availability or scalability is required.

3. RDS for the Database

Amazon RDS provides managed relational databases.
The database should generally not be exposed directly to the internet.
Instead:
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Internet
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Application
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RDS
The RDS security group should allow database connections only from the application servers that need them.

4. IAM and Least Privilege

AWS IAM controls access to AWS resources.
Applications should use IAM roles with only the permissions they require.
Avoid storing AWS credentials directly in application code or Git repositories.
A simple principle is:
Give users and applications only the permissions they actually need.

5. Security Groups

Security Groups act as virtual firewalls.
For example:
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Internet → HTTPS → Load Balancer
Load Balancer → Application → EC2
EC2 → Database Port → RDS
Avoid unnecessarily opening ports such as SSH to the entire internet.

6. Monitoring with CloudWatch

Amazon CloudWatch helps monitor AWS resources and applications.
It can collect:
  • CPU metrics
  • Application logs
  • Network metrics
  • Alarms
  • System activity
Monitoring makes it easier to detect performance problems and investigate incidents.

Security Checklist

Before deploying an application, consider:
  • Keep databases private.
  • Use least-privilege IAM permissions.
  • Avoid hardcoded credentials.
  • Use HTTPS.
  • Restrict unnecessary ports.
  • Enable monitoring and logging.
  • Encrypt sensitive data.

Conclusion

Building an AWS application is not just about launching an EC2 instance.
A good cloud architecture combines networking, compute, storage, databases, security, and monitoring.
Once these fundamentals are understood, the next step is to automate the infrastructure using tools such as Terraform, CloudFormation, or AWS CDK.
The best way to learn AWS is still simple: build something, secure it, monitor it, and then automate it.
# amazon-ec2# devops
Any opinions in this article are those of the individual author and may not reflect the opinions of AWS.
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