Which is better: microservices or monoliths?

There is no universal "best" solution. The choice between microservices and monoliths depends on the specific needs of the project, its scale, the team, and business goals.

Monolith

• Pros:
  • Easier to develop in the initial stage.
  • Easier to test and debug.
  • Less overhead for infrastructure and communication.
  • Easier to organize transactions.
• Cons:
  • Difficult to scale individual components.
  • Changes in one module may affect others.
  • Difficult to use different technologies for different parts of the application.
  • "Big ball of mud" as it grows.

Microservices

• Pros:
  • Easier to scale individual services.
  • Allows using different technologies for different services.
  • Facilitates independent deployment of services.
  • Increases resilience to failures (failure of one service does not necessarily affect others).
  • Promotes agile development in large teams.
• Cons:
  • Complexity in development and management.
  • Higher infrastructure overhead (network, API Gateway, Service Discovery).
  • Complexity in testing and debugging distributed systems.
  • Solving issues with distributed transactions.
  • Requires highly skilled team.

When to use what:

• Monolith: Startups, small projects where time-to-market is critical, teams with limited microservices experience.
• Microservices: Large, complex applications requiring scaling, teams experienced with distributed systems, when different technologies are needed.

Often, teams start with a monolith and as it grows, split it into microservices (the "Strangler Fig" strategy).

# Example of deploying a monolith
docker build -t my-monolith .
docker run -p 8080:80 my-monolith

# Example of deploying two microservices
docker build -t user-service ./user-service
docker build -t product-service ./product-service
docker run -d -p 8081:80 user-service
docker run -d -p 8082:80 product-service

Comparison table:

Characteristic	Monolith	Microservices
Initial development	Simpler	More complex
Scaling	Difficult	Easier (per service)
Change	High risk of affecting everything	Low risk (within the service)
Technologies	Usually one	Multiple technologies possible
Deployment	Whole system	Independent per service
Resilience	Low (single point of failure)	High (failure of one service is not critical)
Infrastructure	Simpler	More complex (additional components needed)
Teams	Better for small teams	Better for large (independent teams)

The choice should be conscious and based on an analysis of the project requirements. Hybrid approaches are also possible.