Cloud

How Not to Build an Application in the Cloud: Common Mistakes to Avoid

How Not To Build an Application in the Cloud

What are the common mistakes to avoid when building an application in the cloud?

Some of the most frequent cloud development mistakes include deploying all application components on a single server, exposing databases to the public internet, using dynamic IP addresses, skipping automated backups, and building on architectures that don’t support horizontal scaling or multi-AZ availability. These issues can cause costly downtime, security breaches, and performance bottlenecks.

How Cloud Computing Changed the Game for SMBs

Cloud computing has revolutionized how small and medium-sized businesses (SMBs) build applications. Platforms like AWS have drastically lowered the barrier to entry, allowing companies to create custom solutions that meet their unique needs without investing in physical infrastructure.

However, while building applications in the cloud seems simple, many organizations unknowingly fall into traps that lead to bloated costs, instability, and poor performance. This case study explores one such real-world example and breaks down how things could’ve been done better — and how you can avoid making the same mistakes.

Key Stakeholders in Cloud App Development

Every cloud project involves a variety of decision-makers and implementers. In this scenario, we had three primary stakeholders:

1. The SMB Owner

The visionary who wanted a custom-built application to support internal inventory and order management. Their goal was a lean, efficient tool tailored to business operations — without the recurring fees of an off-the-shelf SaaS product.

2. The Development Team

An outsourced group responsible for coding the backend logic, designing the user interface, and setting up the database. They had experience with Microsoft server environments and chose AWS for deployment.

3. The Managed Service Provider (MSP)

This team managed the AWS infrastructure. They maintained the hosting environment and had oversight over the deployed resources, often coordinating between the SMB owner and the dev team.

application development ecosystem

Cloud Architecture Overview of the Inventory App

The team collaborated to build a cloud-hosted inventory and order management system with three main layers:

  • Web Frontend – The user interface accessed via browser
  • Business Logic Tier – The middle layer that processes requests
  • Database Tier – Stores all business-critical data

The Initial Cloud Setup

The app was deployed entirely on a single Microsoft Server EC2 instance, hosted in AWS. This “all-in-one” setup, while simple, introduced several significant risks — many of which only became apparent after launch.

Why Hosting Everything on One EC2 Instance Was a Critical Mistake

Encapsulation of All Tiers

All three application layers — frontend, business logic, and database — lived on one virtual machine. That created a single point of failure. If that one instance went down, the entire application would become inaccessible.

Lack of Scalability

Because everything was on a single EC2 instance, horizontal scaling was impossible. The only way to handle more users or traffic was by vertically scaling (adding more CPU/RAM), which quickly becomes expensive and inefficient.

Single Availability Zone (AZ) Risk

All resources were tied to one AWS Availability Zone. If that AZ experienced downtime — due to maintenance or failure — the application would go down with it. No redundancy meant no resilience.

Public Exposure of Sensitive Components

The EC2 instance was directly accessible from the internet. This meant the database layer was publicly reachable — a major security vulnerability. A better approach would isolate the logic and database tiers in private subnets.

Dynamic IP Address Usage

Instead of assigning a fixed Elastic IP, the app used a dynamic public IP. As a result, every time the instance rebooted, its IP could change — breaking the GoDaddy domain’s DNS mapping.

No Automated Backups

There were no snapshot policies or backup strategies in place. If the EC2 instance failed or was deleted, the entire application — and its data — would be lost permanently.

Summary: Problematic vs Best Practice Architecture

Here’s a simple table summarizing the major issues:

Component/FeaturePoor ImplementationBest Practice Recommendation
App HostingAll tiers on one EC2 instanceDecouple into separate tiers
IP AddressDynamic IPUse Elastic IP
AvailabilitySingle AZMulti-AZ deployment
SecurityPublic access to all componentsPrivate subnets with minimal public exposure
Backup StrategyNoneUse automated snapshots or RDS backups
ScalabilityVertical scaling onlyUse autoscaling groups for horizontal scaling

How These Cloud Missteps Affected Performance and Cost

Performance Limitations

Because the app couldn’t scale horizontally, its performance dipped significantly under moderate load. Adding resources manually was the only option — and it wasn’t cheap.

Security Vulnerabilities

Leaving all tiers accessible from the public internet exposed the app to malicious scans and attacks. Security best practices in the cloud demand network isolation and firewall policies.

Downtime Risk

A single Availability Zone meant no failover path. If something happened in that AZ — and it does happen — the entire app went offline.

High Cost with Low Efficiency

The monthly AWS bill exceeded $250. For what was essentially a lightweight inventory tool, this cost was unjustifiable — especially since a properly designed architecture could run for much less.

poor IT infrastructure

Why These Implementation Issues Matter

  1. Performance Limitations: without horizontal scaling, the application risked overload during simultaneous user access. The only workaround was vertical scaling, which increased costs significantly.
  2. Availability Risks: hosting in a single AZ made the application vulnerable to downtime if the AZ experienced issues.
  3. Security Concerns: direct exposure to the public internet increased the risk of cyberattacks. Isolating tiers in private subnets could have mitigated this.
  4. Configuration Challenges: the dynamic IP address required manual updates to maintain URL functionality.
  5. Data Loss Risks: without automated snapshots, recovering from an instance failure was nearly impossible.

What Would a Better AWS Cloud Architecture Look Like?

Decoupled Design

Each application tier should have its own resource — or be hosted using managed services:

  • Frontend: Host using S3 and CloudFront for better performance and lower cost.
  • Business Logic: Deploy on an EC2 instance in a private subnet — or use AWS Lambda for serverless architecture.
  • Database: Use Amazon RDS with encryption, backup, and monitoring baked in.

Enhanced Architecture Improvements

  • Autoscaling Groups: Allow the logic tier to scale based on demand.
  • Multi-AZ Deployment: Ensures high availability across AWS regions.
  • Private Subnets + NAT Gateway: Secure internal components.
  • Elastic IP: Ensures static access for DNS mapping.
  • Automated Snapshots & RDS Backups: Ensures data resilience and fast recovery.
how to deploy healthcare technology components

Key Improvements:

  • Autoscaling Groups: separate EC2 instances for each tier could be placed in autoscaling groups to dynamically manage demand.
  • Multi-AZ Deployment: distribute resources across multiple AZs to ensure high availability.
  • Enhanced Security: use private subnets for the logic and database tiers, and apply security group rules to minimize the attack surface.
  • Elastic IP Addressing: associate an Elastic IP with the EC2 instance to ensure URL consistency.
  • Automated Backups: configure regular snapshots to prevent data loss and simplify recovery.
system architecture enhancements

Real-World Fixes Implemented by Gart

When Gart Solutions stepped in, the client needed to stabilize the current environment during their migration to a new solution. Here’s what we immediately fixed:

  • Created EC2 Snapshots for manual backup
  • Assigned an Elastic IP for DNS stability
  • Updated the GoDaddy DNS Record to the new static IP

While these fixes improved the existing environment, they also highlighted how the app could have been built more effectively from the start.

Conclusion: Build Smarter, Not Just Faster in the Cloud

This story isn’t just about one company’s missteps — it’s a cautionary tale for any organization building in the cloud. Misusing cloud infrastructure can be costly, risky, and inefficient.

But with thoughtful architecture, security-focused design, and scalable components, even small businesses can build reliable, high-performing cloud apps.

Don’t treat the cloud like a virtual closet to stuff everything into. Treat it like the powerful ecosystem it is — and you’ll unlock the speed, resilience, and savings it promises.

Top 5 Lessons to Avoid Cloud App Failures

  1. Never host all tiers on one instance
  2. Avoid public exposure of sensitive services
  3. Use Elastic IPs for stable DNS resolution
  4. Automate your backups
  5. Design for scalability and availability from day one

Have You Faced Cloud Architecture Challenges?

What were your takeaways? Share your experiences — or reach out if you’d like help optimizing your cloud strategy.

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FAQ

1. What are the most common mistakes when building cloud applications?

The most common cloud application mistakes include placing all components on a single server, exposing sensitive resources to the public internet, skipping backup automation, relying on a single availability zone, and ignoring scalability or cost optimization best practices.

2. Why is it bad to host all app tiers on one EC2 instance?

Hosting all application tiers on a single EC2 instance creates a single point of failure, limits scalability, increases security risks, and often leads to higher AWS costs. Decoupling tiers allows for better performance, security, and maintainability.

3. How can I make my AWS-hosted application more scalable and secure?

To improve scalability and security, use autoscaling groups, deploy across multiple availability zones, isolate services in private subnets, enforce strict security group rules, and implement automated backups using RDS or snapshot policies.

4. What’s the difference between Elastic IP and dynamic IP in AWS?

An Elastic IP in AWS is a static, public IP address that remains consistent even after instance restarts, while a dynamic IP can change upon reboot. Using an Elastic IP ensures stable DNS mappings and consistent access to your application.

5. How do I avoid data loss in my cloud-hosted application?

To prevent data loss, implement regular automated backups using snapshots or managed services like Amazon RDS. Store backups in multiple availability zones and test recovery procedures to ensure business continuity in case of failure.

6. What are the risks of hosting all tiers on a single EC2 instance?

Hosting all tiers on a single EC2 instance creates several risks: - Single Point of Failure: If the instance fails, the entire application goes offline. - Scalability Issues: It prevents horizontal scaling, leading to performance bottlenecks. - Security Vulnerabilities: Exposing all components to the public internet increases the risk of attacks. - Data Loss Risks: Without backups or redundancy, data may be irretrievably lost in the event of failure.

7. What’s the benefit of deploying resources across multiple Availability Zones (AZs)?

Using multiple AZs ensures high availability. If one AZ experiences downtime, the application can continue operating from another, minimizing disruptions and enhancing reliability.

8. How does autoscaling improve performance?

Autoscaling dynamically adjusts the number of running instances based on demand. This ensures sufficient resources during peak times and reduces costs during periods of low activity.

9. Why is an Elastic IP address better than a dynamic public IP?

An Elastic IP address remains consistent even when an EC2 instance is stopped and restarted. This ensures uninterrupted application access and avoids manual updates to URLs.

10. What role does AWS RDS play in database management?

AWS RDS provides managed database services with built-in features like automated backups, failover support, and scaling. It simplifies database management while improving reliability and performance.

11. What are the biggest mistakes to avoid when designing an AWS-hosted application?

Some common mistakes include: - Hosting all tiers on a single EC2 instance. - Failing to implement backups or disaster recovery. - Neglecting security best practices, such as using private subnets. - Overlooking the need for scalability and high availability.

12. What steps can I take to optimize costs for a temporary AWS application?

- Schedule the EC2 instance to start and stop during specific hours. - Use snapshots to back up data and configurations. - Implement an Elastic IP for consistent access during the application lifecycle.
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