In the ever-evolving landscape of software development, the adoption of microservices architecture has become a prevailing trend, revolutionizing the way modern applications are built, deployed, and scaled. Microservices are small, independent, and loosely coupled services that work together to form a cohesive application. This architectural style, characterized by its modularity and flexibility, allows development teams to break down complex applications into manageable, independently deployable services. However, harnessing the power of microservices effectively requires adhering to a set of best practices that ensure seamless integration, efficient communication, and overall system resilience.
In this article, we will explore essential best practices for using microservices, exploring key strategies that development teams can employ to leverage the full potential of this revolutionary approach to software design.
Best Practices for Using Microservice
Here are several recommended best practices to consider when implementing microservices effectively:
Best Practice 1: Single Responsibility Principle
This principle emphasizes that each microservice should have only one responsibility. It means that a microservice should be designed around a specific business capability or function, and it should only contain the logic related to that capability. This makes the microservice easier to understand, develop, and test.
Here’s an example of how you might implement the OrderService class in Java, adhering to the Single Responsibility Principle:
import org.springframework.stereotype.Service;
@Service
public class OrderService {
private final OrderRepository orderRepository;
public OrderService(OrderRepository orderRepository) {
this.orderRepository = orderRepository;
}
public Order createOrder(Order order) {
// Logic to create order
return orderRepository.save(order);
}
public Order getOrder(Long id) {
// Logic to get an order
return orderRepository.findById(id).orElse(null);
}
public void deleteOrder(Long id) {
// Logic to delete an order
orderRepository.deleteById(id);
}
}In this example, the OrderService class has a single responsibility: managing orders. It uses an OrderRepository to interact with the database and provides methods to create, retrieve, and delete orders. This makes the OrderService class easier to understand, develop, and test.
Do’s:
Ensure each microservice focuses on a single business capability.
Make sure the microservice only contains the logic related to its responsibility.
Don’ts:
Avoid designing a microservice that takes on multiple responsibilities.
Don’t let a microservice become too large or complex, as it can become difficult to maintain and understand.
Best Practice 2: Separate Data Store
Each microservice should have its own separate data store. This ensures that the microservice is loosely coupled with other microservices and can evolve independently. The choice of the database (SQL, NoSQL, etc.) can be made based on the specific needs of the microservice.
For example, an OrderService microservice might use a SQL database to store order data, while a ProductCatalogService might use a NoSQL database to store product information.
Here are examples of how you might set up an OrderService microservice with a SQL database and a ProductCatalogService microservice with a NoSQL database using Spring Boot and Spring Data:
For the OrderService microservice:
import org.springframework.data.jpa.repository.JpaRepository;
public interface OrderRepository extends JpaRepository<Order, Long> {
}
@Service
public class OrderService {
private final OrderRepository orderRepository;
public OrderService(OrderRepository orderRepository) {
this.orderRepository = orderRepository;
}
public Order createOrder(Order order) {
return orderRepository.save(order);
}
}
In this example, OrderService uses a SQL database through the OrderRepository which extends JpaRepository.
For the ProductCatalogService microservice:
import org.springframework.data.mongodb.repository.MongoRepository;
public interface ProductRepository extends MongoRepository<Product, String> {
}
@Service
public class ProductCatalogService {
private final ProductRepository productRepository;
public ProductCatalogService(ProductRepository productRepository) {
this.productRepository = productRepository;
}
public Product createProduct(Product product) {
return productRepository.save(product);
}
}In this example, ProductCatalogService uses a NoSQL (MongoDB) database through the ProductRepository which extends MongoRepository.
Do’s:
Ensure each microservice has its own private data store.
Choose the right database solution that suits the microservice’s needs.
Don’ts:
Avoid sharing a data store between two or more services.
Don’t allow other services to directly access a service’s private data store.
Best Practice 3: Asynchronous Communication
Microservices should communicate with each other asynchronously to achieve loose coupling. This means that a microservice sends a message without waiting for a response, allowing it to continue processing other tasks. This can be achieved using message queues or event-driven architectures.
For example, consider a service that sends a message using RabbitMQ in Java:
@Autowiredprivate RabbitTemplate rabbitTemplate;
public void sendMessage(String message) {
rabbitTemplate.convertAndSend("exchangeName", "routingKey", message);
}
In this example, the sendMessage method sends a message to a RabbitMQ exchange asynchronously.
Do’s:
Use asynchronous communication to achieve loose coupling between microservices.
Use message queues or event-driven architectures for asynchronous communication.
Ensure that the microservice can continue processing other tasks while waiting for a response.
Don’ts:
Avoid synchronous communication that could make the microservice wait for a response before it can continue processing other tasks.
Don’t tightly couple microservices by making them directly dependent on each other.
Avoid using asynchronous communication if the processing needs to be real-time — i.e. if there is a hard constraint on the response time of a certain request.
Best Practice 4: Fault Tolerance
Microservices should be designed to handle failures gracefully. This can be achieved using techniques like retries, fallback methods, and circuit breakers.
For example, consider a service that uses Hystrix in Java:
@HystrixCommand(fallbackMethod = "fallbackMethod")public String riskyMethod() {
// Logic that might fail
}
public String fallbackMethod() {
// Fallback logic
}
In this example, if riskyMethod fails, Hystrix will call fallbackMethod as a fallback.
Do’s:
Design your microservices to be fault-tolerant.
Handle errors/exceptions gracefully by providing an error message or a default value.
Use techniques like retries, fallback methods, and circuit breakers to handle failures.
Distinguish retryable errors from non-retryable. It’s pointless to retry a request when a user doesn’t have permission or the payload isn't structured properly. Contrary, retrying request timeouts or 5xx is good.
Don’ts:
Avoid designing a microservice that cannot handle failures.
Don’t let a failure in one service bring down the entire system.
Avoid creating a retry storm — a situation when every service in the chain starts retrying their requests, therefore drastically amplifying the total load.
Best Practice 5: API Gateway
An API Gateway acts as a single entry point for all client requests and routes these requests to the appropriate microservice1. It can also handle cross-cutting concerns like authentication, logging, and rate limiting.
For example, consider a configuration for Spring Cloud Gateway in application.yml:
spring:
cloud:
gateway:
routes:
- id: order_service
uri: lb://ORDER-SERVICE
predicates:
- Path=/api/orders/**In this example, the API Gateway routes all requests with paths starting with /api/orders/ to the ORDER-SERVICE microservice.
Do’s:
Use an API Gateway as a single entry point for all client requests.
Ensure the API Gateway routes requests to the appropriate microservice.
Handle cross-cutting concerns like authentication, logging, and rate limiting at the API Gateway.
Keep the API Gateway simple. It should handle request proxying and/or request aggregation if needed.
Maintain API versions. The API Gateway should forward the request to one or more APIs, each with potentially different versions.
Ensure the API Gateway is lightweight and can scale easily.
Don’ts:
Avoid making the API Gateway a single point of failure. If the API Gateway fails, the entire system could fail.
Don’t add unnecessary complexity to the API Gateway.
Avoid making the API Gateway a bottleneck. If not implemented correctly, it can become a bottleneck.
Don’t forget to handle additional latency that might be introduced by the API Gateway.
Best Practice 6: Deploy into Container
Deploying microservices into containers is a process where each microservice of an application is packaged into a container and then deployed. This approach has several advantages:
Isolation: Each microservice runs in its own container, ensuring that it runs in a consistent environment. This isolation reduces conflicts between different microservices and makes it easier to manage each microservice independently.
Scalability: Containers can be easily scaled up or down based on the demand for each microservice. This allows for efficient use of resources and improves the responsiveness of the application.
Portability: Containers include everything a microservice needs to run, making it easy to move the microservice between different environments. This portability simplifies the deployment process and makes it easier to manage the application across different stages of the development lifecycle.
Consistency: By deploying microservices into containers, you ensure consistency across multiple deployment environments, making it easier to manage and troubleshoot the application.
Efficiency: Containers are lightweight and start quickly, making them a more efficient choice for deploying microservices compared to other methods like virtual machines.
In this process, Docker is used to package the microservice and all its dependencies into a container image. This image is then deployed to a container runtime environment, where it runs in isolation from other containers. The container runtime provides the necessary resources for the container to run and manages the lifecycle of the container.
Here is an example of a Dockerfile for a Node.js application:
# Use an official Node.js runtime as the base image
FROM node:14
# Set the working directory in the container to /app
WORKDIR /app
# Copy package.json and package-lock.json to the working directory
COPY package*.json ./
# Install the application dependencies
RUN npm install
# Copy the application code to the working directory
COPY . .
# Expose port 8080 in the container
EXPOSE 8080
# Run the application when the container launches
CMD ["npm", "start"]"Here are some best practices and things to avoid when working with Dockerfiles:
Do use a .dockerignore file to specify files and directories that should not be copied into the container. This can help to reduce build context size and prevent sensitive information from being included in the image.
Do use multi-stage builds to keep your images small. Large images can slow down deployment and take up unnecessary disk space.
Do not run your applications as root in the container. It’s a good practice to use a non-root user for running applications to enhance security.
Do not use latest as the tag for your base image, as this can lead to unpredictable behavior if the image gets updated. It’s better to use a specific version number, as you’ve done in your Dockerfile.
Do not include unnecessary files in your container. Only include the files that are necessary to run your application.
Other Best Practices
Keep Code at a Similar Level of Maturity: This means that all your microservices should be updated and refactored at a similar pace to avoid compatibility issues. This can be managed through proper version control and continuous integration practices.
Separate Build for Each Microservice: Each microservice should have its own build and deployment pipeline. This can be achieved using tools like Jenkins, Travis CI, or GitHub Actions.
Design Stateless Services: Stateless services do not store any information about the current state. This makes them scalable and easy to manage. In a RESTful API, this means that each request should contain all the information needed to process the request.
Adopt Domain-Driven Design: This involves designing your microservices based on business capabilities. For example, in an e-commerce application, you might have separate microservices for User Management, Product Catalog, Order Processing, and so on.
Design Micro Frontends: This involves breaking up your frontend into smaller, more manageable pieces, much like how you break up your backend with microservices. Each micro frontend can be developed, tested, and deployed independently.
Use containers to package and deploy services quickly and securely: This can be achieved using containerization tools like Docker and orchestration tools like Kubernetes.
Utilize service discovery tools such as Consul or Kubernetes to manage service dependencies: Service discovery tools help in managing services and their instances. Consul, Eureka, and Kubernetes are some of the tools that can be used for service discovery.
Utilize an API gateway such as Kong or Tyk to handle requests efficiently: An API gateway acts as a single entry point for all client requests and routes the requests to appropriate microservices.
Adopting a decentralized approach: In a microservices architecture, each microservice is an independent entity. Decentralization helps in scaling the microservices independently.
Aligning services with enterprise capabilities: The microservices should be designed around business capabilities.
Conclusion
Adhering to these microservices' best practices is the key to harnessing the full potential of this architectural approach. By maintaining clear service boundaries, effective communication, robust testing, and a commitment to continuous improvement, you can ensure the success of your microservices projects. Embrace these principles to navigate the ever-changing software development landscape and unlock the benefits of microservices for your organization.