AWS Architecture Design: Secure, Resilient & Cost-Optimised

Designing a new system on Amazon Web Services (AWS) includes planning and building scalable and secure infrastructure using core services.

But the responsibility isn't restricted to ensuring scalability. You must also ensure that the system is safe, runs efficiently, and doesn't inflate the company budget. This is where the role of an AWS solutions architect becomes important.

This article is a breakdown for professionals to design a secure, resilient, high-performing, and cost-effective AWS solution. These design areas give you a clear framework to work from, especially when designing the system for the first time.

Why does an AWS Architecture Design Matters?

AWS design principles are basically the rules that govern your choices, especially since there are several ways to build a cloud solution. Here are a few instances:

• Maintain access control so any unauthorised user cannot make any changes.
• Use multi-AZ deployments so that the application keeps running even if a component fails.
• Planning scalability solutions so that the cloud system can handle the changing requirements.
• Data encryption so the user's sensitive information is always safe.

Working on high-performance architectures helps design solutions that require minimal changes after launch. Redesigning a solution or working on an existing system requires extra time and effort. That's why the AWS design matters.

AWS follows a Well-Architected Framework which covers the following core areas:

• Operational excellence
• Security
• Reliability
• performance efficiency
• cost optimisation
• Sustainability

There are six pillars in the AWS Well-Architected Framework, however, the building of a solution is more about security, resilience, performance and cost optimisation.

What is Multi-Tier Architecture?

A multi-tier architecture breaks down an application into various layers, and each layer performs a specific task. It enables you to deploy application components, manage access and scale resources efficiently.

There are three levels:

Presentation tier

This layer receives incoming requests via an app/website. Elastic Load Balancing and Amazon CloudFront are also helpful for content delivery and traffic distribution.

Application tier

The second layer handles requests and application logic. AWS Lambda and EC2 can efficiently handle these workloads depending on the requirements of the current application.

Data tier

The last layer is in charge of storing and managing the data of the application. You can use Amazon RDS for relational databases and Amazon DynamoDB for a managed NoSQL database.

Architects commonly depend on Auto Scaling to adjust the compute capacity and meet the ongoing demand. They also divide resources across multiple Availability Zones.

However, every AWS solution would not go through the same process. It ultimately depends on the application's complexity, security requirements, availability targets and budget.

Let's look at the key design principles, relevant AWS services, and example architectures for each of these four areas.

Design Secure Solutions

Security is a critical part of AWS architecture design. Architects must ensure that users and services have only the permissions they need, protect sensitive information, and monitor activity to identify potential threats.

Key services of a secure AWS architecture:

• AWS IAM controls everyone's roles so there is no chance of password leaks.
• Security groups work as virtual firewalls, only allowing the traffic that's on the list.
• AWS KMS creates keys for encryption in Amazon RDS, EBS and S3.
• The managed web application firewall (WAF) blocks web attacks before they can interfere with the server.

Example: AWS is hosting an eCommerce application that runs in a Virtual Private Cloud. In this app, only the load balancer faces the internet, while the web, app and database are present in the private subnets. This database is encrypted through a KMS key, and the traffic uses TLS. In case an attacker is able to find a loophole in the web, they still cannot access the database. That's how the architecture works.

In case a reliable professional (architect) isn't available on site, teams often make the mistake of opening the security group to the public for testing and forget to close it.

Ensure Resilient Architecture

If a design is fault-tolerant or covers the downtime quickly, your cloud will keep operating at all times. An architect's job is to identify the possible failure points and plan for backup and recovery along with distributing workloads across multiple Availability Zones. The exact approach depends on the application requirements.

Key services of a resilient AWS architecture:

• The Elastic Load Balancing checks the server health and sends traffic only to the working ones.
• Auto Scaling can replace failed instances with the ones that are working.
• AWS Backup helps in automated data protection across services.
• Amazon SQS enables tiers to work independently so that a slow part does not freeze the rest.

Example: Every app tier runs in two Availability Zones. In case one goes down or its server fails the health check, the load balancer stops sending users there. Meanwhile, the other zone continues to receive traffic. Auto Scaling launches new instances to replace failed ones and RDS promotes the standby database in Zone B, typically within one to two minutes. In such instances, there may be a slight delay for users.

Focus on High-Performing Architecture

A high-performing architecture matches the expectations when computing, storing, and using networking resources efficiently. An architect is majorly responsible for selecting a suitable resource type, identifying bottlenecks, and monitoring performance for every workload.

When working on cloud solutions, performance isn't restricted to big servers. It shifts to picking the right resource for every job.

Key services include the following:

• Amazon CloudFront that delivers content through a global content delivery network.
• Amazon ElastiCache to maintain backup so there are minimal queries.
• Amazon EC2 provides a customisable computing capacity for workloads.
• Amazon CloudWatch collects logs so that the architect can monitor the application performance.

Example: Let's say a website is busy every evening. CloudFront will serve images from locations closest to every visitor. So most of the requests don't reach your servers. At the same time, ElastiCache keeps the database consolidated. At times when the traffic grows, Lambda is beneficial for working in the background on tasks like resizing an uploaded photo.

Optimise Cost for Every Solution

When an architecture is cost-saving, it meets the business requirements without paying for extra resources. An architect is responsible for matching capacity with the workload demand and choosing a suitable pricing model accordingly. However, cost optimization should not come at the expense of the solution's security or performance.

Key services of a cost-optimised architecture:

• A savings plan saves cost over long-term usage.
• Spot Instances utilises spare AWS capacity at a discount and can be interrupted. Always use them for work that's dispensable.
• S3 storage classes and lifecycle rules shift old data to better storage options automatically.
• AWS Budgets and Cost Explorer keeps a track of the expenses and give warnings early.

Example: Imagine that an application gets extensively used during business hours. However, the demand reduces at night. The Amazon EC2 Auto Scaling adjusts the events according to the workload requirements. Your team can utilize Compute Optimiser for review and Cost Explorer to keep a track of spending. These measures help control costs and maintain the needed capacity.

The four designs closely relate to each other. An AWS architect has to evaluate the trade-offs to find the best solutions and meet the requirements simultaneously. You can learn more about the AWS design principles from the official Microsoft documentation.

What are the Common Trade-Offs in AWS Architecture Design?

When you are designing an AWS architecture, you have to maintain a balance between the requirements. A choice can improve one area but compromise the other. That's where an AWS architect comes into action and evaluates these tradeoffs.

Conclusion

An efficient architecture should balance security, resilience, performance and cost optimisation. It is important to understand how these areas interact to be able to make informed decisions and build solutions that meet business needs.

Professionals may prepare for real-world cloud challenges by implementing these principles through hands-on labs and practice papers. The AWS Certified Solutions Architect - Associate certification provides a pathway for professionals who want to validate these skills and prove their knowledge of how to design secure, resilient, high-performing and cost-optimised solutions on AWS.