A practical guide from 14 years of building systems that grow

Introduction: Why This Guide Matters

There are a lot of courses lectured in universities, but only a few of them try to teach real-world problems like designing scalable software architecture, secure coding, and other practical challenges that engineers face daily. I always wanted to write something about these kinds of problems I’ve faced throughout my career, and I think the time has come to put pen to paper. I hope this proves beneficial for anyone looking for practical, experience-based knowledge.

I don’t want to go very deep because I’d like this to be understandable by many readers, from junior developers to seasoned architects. My goal is to give you some concrete ideas about which steps I follow before designing an architecture for a system. Hopefully, I’ll extend this article with more detailed architectural design principles in the future.

Please note that everything that follows is based on my experience over the last 14 years, and these approaches are subject to change as technology and best practices evolve. Architecture is never a “solved” problem but a continuous journey of learning and adaptation.

Step 1: Self-Planning: Your Architecture Checklist

First of all, self-planning always comes first. A briefly prepared to-do list that will help you remember completed and remaining basic steps during the work is invaluable. Think of it as your architecture roadmap. It keeps you on track and ensures nothing critical falls through the cracks.

In a general to-do list, the most common points I generally include are:

• Understand the business requirements and constraints
• Identify non-functional requirements (NFRs)
• Define scalability targets and growth projections
• Map out security requirements and threat models
• Evaluate technology stack options
• Plan for observability and monitoring
• Consider operational complexity and team capabilities
• Document architectural decisions (ADRs)

Step 2: Understanding Requirements: The Foundation of Good Architecture

Before you write a single line of code or draw a single diagram, you need to deeply understand what you’re building and why. This sounds obvious, but it’s where most architectural failures begin. Requirements come in two flavors, and you need both.

Functional Requirements

These define what the system should do. Work closely with product managers, stakeholders, and end users to understand the core functionality. Ask probing questions: What problem are we solving? Who are our users? What are the critical user journeys? Don’t just accept requirements at face value – challenge them, refine them, and ensure you understand the underlying business need.

Non-Functional Requirements (NFRs)

These are often the silent killers of projects. NFRs define how the system should behave and are critical for making architectural decisions. Key NFRs to consider include:

• Performance: What are the response time requirements? What’s the expected throughput?
• Scalability: How many users do we expect now? In one year? In five years?
• Availability: What’s the uptime requirement? Is 99.9% enough, or do we need 99.99%?
• Security: What data are we protecting? What compliance requirements exist (GDPR, HIPAA, SOC2)?
• Maintainability: How easy should it be to modify and extend the system?
• Cost: What are the budget constraints? What’s the acceptable operational cost?

Step 3: The Architecture Decision Process

With requirements in hand, you can begin making architectural decisions. But here’s the key insight:

Architecture is about trade-offs, not perfect solutions. Every decision you make has consequences, both positive and negative. Your job is to make informed trade-offs that best serve your specific context.

Choosing an Architectural Style

There’s no one-size-fits-all architectural style. The right choice depends on your requirements, team size, and organizational structure. Here’s a practical framework:

• Monolith: Start here if you’re building a new product with a small team. It’s simpler to develop, deploy, and debug. You can always decompose later when you understand your domain better.
• Microservices: Consider this when you have multiple teams that need to deploy independently, when different parts of your system have different scaling requirements, or when you need technology diversity.
• Event-Driven: Great for systems with complex workflows, loose coupling requirements, or when you need to react to changes in real-time.
• Serverless: Consider when you have unpredictable traffic patterns, want to minimize operational overhead, or have budget constraints that favor pay-per-use models.

Step 4: Designing for Scalability

Scalability isn’t just about handling more users. It’s about maintaining performance characteristics as load increases. There are two fundamental approaches:

Vertical Scaling (Scale Up)

Adding more resources to a single machine. It’s simpler to implement but has physical limits and creates a single point of failure. Good for databases and stateful services where distributed consistency is complex.

Horizontal Scaling (Scale Out)

Adding more machines to distribute load. More complex to implement but offers better fault tolerance and theoretically unlimited scaling. To scale horizontally effectively, design your services to be stateless wherever possible and externalize state to dedicated data stores.

Practical Scalability Patterns

• Load balancing: Distribute requests across multiple instances.
• Caching: Reduce database load with Redis, Memcached, or CDNs.
• Database sharding: Partition data across multiple database instances.
• Asynchronous processing: Use message queues to decouple and buffer work.
• Read replicas: Scale read-heavy workloads with database replication.

Step 5: Security by Design

Security should never be an afterthought. Build it into your architecture from day one. The cost of retrofitting security is orders of magnitude higher than designing it in from the start.

Core Security Principles

1. Defense in Depth: Implement multiple layers of security controls. Don’t rely on a single defense mechanism.
2. Principle of Least Privilege: Grant only the minimum permissions necessary for each component and user.
3. Zero Trust: Never trust, always verify. Authenticate and authorize every request, even internal ones.
4. Secure by Default: Default configurations should be secure. Require explicit action to open up access.
5. Encrypt Everything: Use TLS for data in transit and encryption for data at rest. No exceptions.

Step 6: Planning for Observability

You can’t fix what you can’t see. A well-architected system needs comprehensive observability built in from the start. This means implementing the three pillars of observability:

• Logging: Structured logs that capture what happened, when, and why. Use correlation IDs to trace requests across services.
• Metrics: Quantitative data about system behavior. Track the four golden signals: latency, traffic, errors, and saturation.
• Tracing: Distributed tracing to understand request flow across services. Essential for debugging in microservices architectures.

Don’t just collect data—set up actionable alerts based on SLOs (Service Level Objectives). Alert fatigue is real, so focus on metrics that directly impact user experience.

Step 7: Document Your Decisions

Architecture decisions have long-lasting consequences. Document them using Architecture Decision Records (ADRs). Each ADR should capture the context and problem statement, the decision made, the alternatives considered, and the consequences (both positive and negative).

Future team members (including future you) will thank you when they understand not just what was decided, but why. This context is invaluable when revisiting decisions as requirements evolve.

Final Thoughts: Architecture Is a Journey

Remember that no architecture is perfect, and no architecture is permanent. The best architects I’ve worked with share a common trait: they remain humble and curious. They know that today’s best practices might be tomorrow’s anti-patterns.

Start simple, iterate based on real-world feedback, and don’t be afraid to revisit and refactor your decisions. The goal isn’t to predict the future perfectly but to build systems that can evolve gracefully as your understanding deepens.

I hope this guide serves as a useful starting point for your architectural journey. In future articles, I’ll dive deeper into specific topics like designing for resilience, managing technical debt, and patterns for distributed systems.

Happy architecting!