How to Design Better AWS Architecture Diagrams
Learn how to create clearer and more effective AWS architecture diagrams by improving communication flow, defining scope, separating responsibilities, and applying practical cloud design principles.
What is a Diagram?
A simple definition I learned in college is the following:
A software diagram is a set of lines, shapes, and arrows used to visually represent the behavior, flow, and interaction between components of an application.
In other words, a diagram is a way to translate complex technical ideas into something visual, making it easier to understand both for the people building the solution and for those consuming it.
More than just a drawing, a diagram is a communication tool. It helps tell the story of the application: how it starts, how data flows, where it is processed, and where it is stored. This becomes extremely valuable when it’s time to actually build the solution.
Why do we need diagrams?
Creating diagrams brings several benefits, especially when working with distributed systems and cloud architectures:
- Visualizing application behavior even before writing code
- Anticipating bottlenecks, such as excessive requests, single points of failure, or poorly defined dependencies
- Improving development planning, helping define where implementation should start
- Aligning teams, avoiding different interpretations of the same architecture and helping divide responsibilities across teams working on the same application by clearly defining input and output payloads between components
In addition, diagrams can be created using different formats and modeling approaches depending on the goal. Some common examples are:
- ERD (Entity Relationship Diagram) for database modeling
- UML for representing classes, components, or workflows
- Cloud architecture diagrams to represent services, integrations, and responsibilities
The most important aspect is not the diagram language itself, but having something visual and clear that represents the architecture as a whole.
Visually, they usually look like this:
- ERD
- UML
- Cloud architecture diagrams
Understanding the application flow
A good diagram makes the communication flow between services, applications, and databases explicit. This becomes essential when dealing with:
- Multiple services interacting with each other
- Asynchronous integrations (queues, events, streams)
- Shared databases
Visualizing the flow makes it much easier to:
- Understand dependencies
- Identify unnecessary coupling
- Evaluate the impact of future changes
For example, choosing a flow such as application → SNS → SQS can be extremely valuable if, in the future, multiple applications need to consume the same payload produced by a system using a fan-out pattern.
The importance of defining diagram scope
One extremely important — and often ignored — aspect is defining the scope of the diagram.
The same system can (and should) have different diagrams depending on the target audience. More important than the technical depth is being able to deliver the right message to the right audience.
Business stakeholders
At this level, it usually doesn’t make sense to discuss details such as VPCs, public/private subnets, or routing tables. The focus is generally on:
- Solution behavior
- Cost
- Performance
- Response time
Development teams
For technical teams, a more detailed diagram makes sense, including:
- Clearly specified services
- Detailed workflows
- Explicit dependencies
- Input and output payloads
Leadership and management
For leadership, the ideal diagram is usually more abstract, focusing on:
- Business value
- Scalability
- Risks and reliability
At this level, visually indicating system boundaries and associated risks can be very useful, for example by using dashed blocks or clear delimitations.
In other words: there is no single diagram that fits every scenario. The diagram should adapt to the context to communicate ideas clearly.
High-level and low-level requirements
Before even starting the final architecture diagram, a very useful practice is applying the EPS concept (Input, Processing, and Output).
This allows you to create a simple high-level flow, for example:
- API receives the request (Input)
- A service or worker applies business logic (Processing)
- Data is persisted or queried from DynamoDB (Output)
This type of diagram helps quickly identify:
- Communication layers
- The role of each service
- Where it makes sense to evolve into more detailed diagrams
From there, you can gradually move toward low-level architecture diagrams.
How to build a diagram in AWS
A very common — and effective — approach is to build from the foundation upward.
For convenience, in this example I use draw.io . It is always important to use the most up-to-date icon pack possible.
Start with the foundational components:
- AWS Account and Region
- VPC
- Availability Zones
- Subnets
- Internet Gateway / NAT Gateway
From there, evolve into the application services:
- SQS
- Lambda
- API Gateway
- Databases (DynamoDB, RDS, etc.)
A good visual practice is to separate architecture layers, such as:
- Data ingestion
- Processing
- Persistence
This can be done using:
- Dashed blocks
- Visual grouping
- Colored blocks
- Small descriptions below each layer
This organization makes the diagram significantly more readable and helps anyone quickly understand the role of each part of the architecture.
In the next sections, I’ll show how to transform these concepts into practical diagrams using official AWS icons and visual best practices.
How to improve an AWS diagram (practical example)
This is the example I’m building based on this context.
Context
I intentionally did not include VPCs and subnets to keep the diagram simpler, since this is an initial architecture diagram and those infrastructure details could create more noise than clarity at this stage.
In the first diagram, we can already see the technical requirements represented, but the flow is still not very clear. The information feels too scattered, and a single Lambda function ends up accumulating validation and processing responsibilities — something that will be improved in the following iterations.
In the second diagram, several things already improve: using a top-down flow makes the request lifecycle and failure paths much clearer. CloudWatch, even represented in a simplified way, already indicates that we have observability for metrics and logs. The arrow from
Lambda_process_order points to the SQS queue because that Lambda is the queue consumer.
In the third diagram, the responsibilities become much better separated, reflecting the original flow more clearly (input → processing → persistence → failure notification). Even so, the diagram could still evolve further depending on the desired level of detail.
Finally, adding colors can help significantly with separating responsibilities across different parts of the system. However, this becomes more of a personal preference: in many cases, dashed boundaries and visual grouping already accomplish this very effectively.
# architecture-patterns# architecture# aws-well-architected# distributed-architecture# solutions-architect
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