When to use microservices (and when not to) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a microservice in simple terms?

A microservice is a small, independent part of a big software system that does one job well and can work on its own.

beginner

When is it a good idea to use microservices?

Use microservices when your system is big, needs to grow fast, different teams work on different parts, or you want to update parts without stopping the whole system.

beginner

What are some reasons NOT to use microservices?

Avoid microservices if your system is small, simple, or your team is small because it adds extra work and complexity.

intermediate

How do microservices help with scaling?

Microservices let you grow only the parts that need more power, like adding more cooks only to the busy kitchen station instead of the whole restaurant.

intermediate

What challenges come with microservices?

They need good communication between parts, careful planning, and tools to watch and fix problems because many small parts can be tricky to manage.

Which situation is best suited for microservices?

A A large app with many teams working on different features

B A simple calculator app

C A small website with one developer

D A static brochure website

Microservices work well when many teams build different parts of a large app.

What is a common downside of using microservices?

A Simplifies deployment

B Increases system complexity

C Reduces communication needs

D Eliminates need for monitoring

Microservices add complexity because many small parts must work together.

When should you avoid microservices?

A When the team is small and system is simple

B When the system is very large

C When you want to scale parts independently

D When you have multiple teams

Small teams and simple systems do better with simpler designs.

How do microservices improve system updates?

A By requiring all parts to update together

B By updating the whole system at once

C By avoiding updates

D By updating one part without stopping others

Microservices let you update one part without affecting the rest.

What is a key requirement for microservices to work well?

A No communication between parts

B One big database for all parts

C Strong communication and monitoring tools

D No need for planning

Good communication and monitoring are essential for managing many small services.

Explain when microservices are a good choice and when they are not.

Think about system size, team size, and complexity.

Describe the main challenges of using microservices and how they affect system design.

Consider what managing many small parts involves.

Practice

1. Which scenario is best suited for using microservices architecture?

easy

A. A large, complex application requiring independent scaling of components

B. A simple, single-function app with a small user base

C. A small script running on a single machine

D. A static website with no backend logic

Solution

1. Step 1: Understand microservices purpose

   Microservices are designed for complex apps where parts can scale or update independently.

2. Step 2: Match scenario to microservices benefits

   A large app needing flexibility and scaling fits microservices well; small or simple apps do not.

3. Final Answer:

   A large, complex application requiring independent scaling of components -> Option A

4. Quick Check:

   Complex app = microservices [OK]

Hint: Use microservices only for complex, scalable apps [OK]

Common Mistakes:

• Choosing microservices for small or simple apps
• Ignoring team size and management overhead
• Assuming microservices always improve performance

2. Which of the following is a correct reason NOT to use microservices?

easy

A. The app requires frequent updates to parts

B. The application is very small and simple

C. The app needs to scale independently

D. The app has multiple teams working on different features

Solution

1. Step 1: Identify when microservices are unnecessary

   Microservices add complexity and overhead, so small simple apps don't benefit.

2. Step 2: Evaluate options

   Options A, B, and D are reasons to use microservices, not avoid them.

3. Final Answer:

   The application is very small and simple -> Option B

4. Quick Check:

   Small app = avoid microservices [OK]

Hint: Avoid microservices for small, simple apps [OK]

Common Mistakes:

• Confusing scaling needs as a reason to avoid microservices
• Ignoring complexity added by microservices
• Assuming microservices fit all team sizes

3. Consider a microservices app with 5 services. If each service requires 2 developers and the team has only 6 developers total, what is the likely outcome?

medium

A. The team can easily manage all services independently

B. The services will merge into a monolith automatically

C. The team will struggle due to insufficient resources for each service

D. The app will automatically scale without developer input

Solution

1. Step 1: Calculate developer needs

   5 services x 2 developers each = 10 developers needed.

2. Step 2: Compare with available team size

   Only 6 developers are available, which is less than 10, causing resource strain.

3. Final Answer:

   The team will struggle due to insufficient resources for each service -> Option C

4. Quick Check:

   Dev shortage = struggle managing microservices [OK]

Hint: Check if team size matches microservices needs [OK]

Common Mistakes:

• Assuming microservices scale developer needs automatically
• Ignoring team size constraints
• Thinking services merge automatically without effort

4. A team tries to convert a small monolithic app into microservices but faces deployment failures and communication errors. What is the most likely cause?

medium

A. Microservices do not support deployment automation

B. The app was too large for microservices

C. They used too many developers

D. They underestimated the complexity of managing microservices

Solution

1. Step 1: Analyze the problem context

   Small apps converted to microservices often face complexity in communication and deployment.

2. Step 2: Identify the cause

   Deployment failures and communication errors usually come from underestimating microservices management overhead.

3. Final Answer:

   They underestimated the complexity of managing microservices -> Option D

4. Quick Check:

   Underestimating complexity = deployment issues [OK]

Hint: Expect extra management work with microservices [OK]

Common Mistakes:

• Blaming microservices for deployment automation lack
• Assuming more developers cause deployment errors
• Thinking large apps cause these specific errors

5. A startup with a small team plans to build a new app. They want to decide between microservices and a monolithic design. Which approach should they choose and why?

hard

A. Start with a monolith to reduce complexity and switch later if needed

B. Start with microservices to prepare for future scaling immediately

C. Use microservices only if the app is a static website

D. Avoid both and build multiple separate apps

Solution

1. Step 1: Consider team size and app complexity

   A small team benefits from simpler monolithic design to reduce overhead and speed development.

2. Step 2: Plan for future growth

   Starting monolithic allows easier initial development; microservices can be adopted later if scaling is needed.

3. Final Answer:

   Start with a monolith to reduce complexity and switch later if needed -> Option A

4. Quick Check:

   Small team = start monolith [OK]

Hint: Small teams start monolith, scale to microservices later [OK]

Common Mistakes:

• Choosing microservices too early for small teams
• Confusing static websites with microservices use
• Ignoring future scalability planning