12 Essential Design Principles for Building Microservices: Practical Examples in Application Development

CONCEPTS

5/21/20242 min read

Microservices architecture relies on several key design principles to ensure scalability, maintainibility and reliability. Here are the twelve fundamental principles that a microservice application should follow.

  1. Single Responsibility Principle - Each microservice should focus on a specific business capability, ensuring that it performs a single function or a set of relaetd functions

  2. Decentralized Data Management - Each microservice should manage its own database, leading to a decentralized approach where services do not share a common database but communciate through APIs.

  3. API Gateway - API Gateway should be created that helps in managing cross cutting concerns like authentication, logging. Centralizing these functions helps in better control and monitoring.

  4. Independent Deployablity - Each microservice should be indepenedently deployable and updatable without affecting other services, allowing for continuous integration and delivery

  5. Continuous Delivery and Deployment - Deployment process should be automated to ensure quick and relaible delivery of services, facilitating continuous updates and improvements.

  6. Fault Isolation - Each microservice should handles its own failure independently without cascading the failures to other services, thereby maintaining system resilience.

  7. Decentralized Governance - Teams should have the freedom to choose the best tools and technologies for their specific services.

  8. Automated Testing - Each microservice should be built with automated tests to maintain quality and reliability, enabling quick detection and resolution of issues.

  9. Infrastructure as Code - Building infrastructure using IaC for all the environments, facilitating consistent and repeatable environments and easier scaling

  10. Service Discovery - Service Discovery mechanisms should be enabled so as to facilitate microservice to microservice communciation without hard-coding any addresses, enabling flexibility and scalability

  11. Monitoring and Logging - Comprehensive monitoring and centralized logging are necessary to track the health and performance of each microservice, helping in debugging and ensuring system reliability.

  12. Security - Implementing security practices, including authentication and authorization at the service level is critical to prevent any unauthorized access and protect data.

Lets provide an example of the above 12 principles can be implemented while developing a microservice application

  1. Single Responsibility Principle - Our microservice has 2 components - User Service, Book Service and Purchase Service. Each of the services manages its own use cases separately like

    • User Service - Manages user creation, authentication

    • Book Service - Manages book categories, quantity

    • Purchase Service - Manages purchase details of a book by a user

  2. Decentralized Data Management - Each of the 3 microservices uses their own database, thereby not sharing any common DB among each other

    • User Service uses MYSQL DB - 'User' Database

    • Book Service uses MYSQL DB - 'Book' Database

    • Purchase Service uses NOSQL DB - Mongo - 'Purchase' Database

  3. API Gateway - Netflix's Zuul is used as an API Gateway for managing all the routings, monitoring and security for the 3 services

  4. Independent Deployablity - Each microservice has their own deployment pipeline configured in Bitbucket and each service can deploy their own code independently without requiring a full deployment of the entire application

  5. Continuous Delivery and Deployment - CI/CD pipeline is created for each of the microservices through Bitbucket enabling various features like unit and e2e testing, linting and finally deploy to proper environments

  6. Fault Isolation - Each microservice handles its own failure. If Purchase service is failing for some reason, User Service and Book Service will still work as usual, enabling users to still be able to browse through books and adding to cart

  7. Decentralized Governance - User Service is built on Node JS, Book Service in Python and Purchase Service is build in Java, enabling freedom to the teams to choose their own tools to build the microservices.

  8. Automated Testing - Each microservice pipeline is enabled with automated unit testing and e2e testing to make sure the application is reliable before deployment

  9. Infrastructure as Code - Terraform is used to create the infrasture which ensures consistent performance in all the environments

  10. Service Discovery - Spring's Eureka is used to enable service discovery

  11. Monitoring and Logging - Kibana tool is used to collect logs from the services and push them to ElasticSearch

  12. Security - Oauth2 tokens are used to enable authorization for all the requests to the microservices.