Architecture design for microservices using gRPC

Architecture design for microservices using gRPC

Hello, Habre!

Microservices architecture offers us a new level of flexibility, scalability and management of complex applications. However, to get the most out of this architecture, it is important to properly design microservices and ensure that they interact effectively.

gRPC is a high-performance and powerful tool for building microservice systems.

Basics of gRPC

gRPC is a high-performance remote procedure call framework developed by Google. It is based on a simple and effective idea – defining remote services and methods using Protocol Buffers, and then creating client and server stubs for efficient interaction between applications. Why is this important?

  • Productivity: gRPC uses a binary protocol, which makes it much more efficient compared to text-based protocols such as JSON. It also supports multiple programming languages, providing high performance for heterogeneous ecosystems.

  • Definition of the interface: With gRPC, you define your services and methods using the gRPC Interface Definition Language (IDL), which provides a strict and unambiguous interface between client and server. This helps avoid misunderstandings and makes the code easier to maintain.

  • Two-way communication: One of the key features of gRPC is support for two-way communication. This means that the client and server can actively communicate and send data to each other, which is especially useful in real-time and streaming applications.

Advantages of gRPC over REST API:

  • Efficiency and productivity: As mentioned, gRPC uses a binary format for data exchange, which results in less network load and faster data serialization and deserialization.

  • Automatic code generation: gRPC automatically generates client and server stubs based on the definitions in the Proto file. This simplifies development and reduces the risk of code errors.

  • Support for many languages: You can use gRPC with a large number of programming languages, making it ideal for heterogeneous microservice architectures.

Main components of gRPC: Protocol Buffers, gRPC IDL and gRPC stubs:

  • Protocol Buffers (Proto): This is a data description language developed by Google. It allows you to define the data structure and services that will be used by your microservices. Proto files become the source of truth for clients and servers and are the basis for code generation.

  • gRPC IDL: This interface description language allows you to define remote services and methods, as well as the messages that are passed between the client and the server. It is a key component in defining the contract between the client and the server.

  • gRPC stubs: This is generated code that provides you with a client and server interface for your methods. They simplify your work and provide automatic data serialization and deserialization.

Installing and configuring gRPC for development

To get started with gRPC, you need to install the libraries for your programming language. For example, for the Python language, you can use pip:

pip install grpcio
pip install grpcio-tools

After installing the libraries, you can create a Proto file defining your services and messages, and then generate the stubs using the utility protoc. This will give you the tools to create clients and servers that can communicate using the gRPC protocol.

Designing microservices with gRPC

Separation of functionality

When designing microservices, it is important to properly separate functionality. Each microservice should be responsible for a certain, well-defined piece of functionality. This will make your system easier to develop, scale and maintain.

Let’s say we have an online store. We can split it into microservices to manage orders, inventory, authentication and payment. Each of them will be responsible only for his area.

Definition of gRPC services and methods

Defining gRPC services and methods is a key step. It defines how clients will interact with your microservices. An example of gRPC service and method definition in the Proto file:

syntax = "proto3";

package ecommerce;

service OrderService {
  rpc CreateOrder (OrderRequest) returns (OrderResponse);
}

message OrderRequest {
  // Поля запроса
}

message OrderResponse {
  // Поля ответа
}

In this example, we have an “OrderService” service that provides a “CreateOrder” method.

Designing messages using Protocol Buffers

Message Protocol Buffers are a way of defining the data that will be transferred between the client and the server. An example of defining a message in a Proto file:

message Order {
  string order_id = 1;
  repeated Product products = 2;
}

message Product {
  string product_id = 1;
  int32 quantity = 2;
}

Messages must be well designed to ensure efficient data transfer and reading.

Working with data schemas and versioning

Data schemas come into play in microservices, especially during versioning. When changing the Proto files, you should ensure compatibility with previous versions.

An example of versioning in a Proto file:

syntax = "proto3";

package ecommerce;

// Версия 1
message OrderV1 {
  string order_id = 1;
}

// Версия 2
message OrderV2 {
  string order_id = 1;
  repeated Product products = 2;
}

Multi-version support can be vital when you upgrade microservices.

Communication between microservices

Methods of calling gRPC services

gRPC provides several methods of calling services:

  1. Unary methods: One request and one response Example:

rpc GetOrder(OrderRequest) returns (OrderResponse);
  1. Server methods: One request and many responses Example:

rpc GetOrders(OrderRequest) returns (stream Order);
  1. Client methods: Many requests and one answer Example:

rpc CreateOrder(stream OrderRequest) returns (OrderResponse);
  1. Bilateral methods: Many requests and many answers Example:

rpc Chat(stream ChatMessage) returns (stream ChatMessage);

The correct choice of method depends on your specific need and allows efficient data exchange between microservices.

Handling of errors and call repetitions

When communicating between microservices, it is necessary to pay attention to error handling and call repetitions. gRPC provides mechanisms for handling errors, including standard error codes (eg OK, NOT_FOUND, INVALID_ARGUMENT) and the possibility of creating user errors.

An example of client-side error handling (in Python):

try:
    response = stub.GetOrder(order_request)
except grpc.RpcError as e:
    if e.code() == grpc.StatusCode.NOT_FOUND:
        # Обработка ошибки NOT_FOUND
    else:
        # Обработка других ошибок

Also, gRPC provides the ability to implement call repetitions using retries and backoff agents, which helps in case of temporary failures.

Authentication and authorization in gRPC

Security is a critical aspect of microservice architectures. gRPC provides capabilities for authentication and authorization, including support for authentication mechanisms such as OAuth, JWT, and TLS.

Example of using JWT for authentication:

rpc CreateOrder (OrderRequest) returns (OrderResponse) {
  option (google.api.http) = {
    post: "/v1/orders"
    body: "*"
  };
  option (grpc.gateway.protoc_gen_grpc.gateway_http) = {
    rules: {
      post: "/v1/orders"
      put: "/v1/orders/{order_id}"
      body: "*"
      response_body: "*"
      custom: {
        name: "authorization"
        pattern: "Bearer [^ ]+"
        value: "{authorization}"
        remove: "Authorization"
      }
    };
  };
  option (grpc.gateway.protoc_gen_grpc.gateway_http_get) = {
    binding: "*"
  };
}

Transaction and Consistency Management

Managing transactions in a microservices architecture is a complex task. gRPC does not provide native transaction support, but you can use other technologies such as Apache Kafka or Apache Pulsar to ensure data consistency between microservices.

It is important to remember that data consistency and transactions must be clearly defined in your microservices design and considered during development.

Scaling and managing microservices

Scaling gRPC microservices

Scalability is one of the main features of microservices architecture. gRPC makes it easy to scale microservices horizontally. As the load on your system grows, you can add new instances of microservices.

An example of scaling using Docker and Kubernetes:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: order-service
spec:
  replicas: 3
  selector:
    matchLabels:
      app: order-service
  template:
    metadata:
      labels:
        app: order-service
    spec:
      containers:
      - name: order-service
        image: your/order-service-image

In this example, we create a Kubernetes Deployment with three replicas for the microservice. As the load increases, Kubernetes can automatically scale the number of replicas.

Version and update management

Versioning support is an important part of managing microservices. Once you release a new version of a microservice, you need to ensure that clients can migrate to the new version without interruption.

An example of using gRPC versioning:

syntax = "proto3";

package ecommerce;

// Версия 1
message OrderV1 {
  string order_id = 1;
}

// Версия 2
message OrderV2 {
  string order_id = 1;
  repeated Product products = 2;
}

Approaches to updates may vary depending on your architecture, but it is important to ensure backward compatibility.

Monitoring and logging for debugging and performance analysis

Monitoring and logging are an integral part of managing microservices. You should be able to monitor your microservices, identify issues, and analyze performance.

For monitoring and logging you can use tools like Prometheus, Grafana, ELK (Elasticsearch, Logstash, Kibana) stack and Zipkin. Example of Prometheus integration in gRPC:

func main() {
  // Инициализация мониторинга Prometheus
  prometheus.MustRegister(server)

  lis, err := net.Listen("tcp", ":50051")
  if err != nil {
    log.Fatalf("failed to listen: %v", err)
  }
  s := grpc.NewServer()

  pb.RegisterOrderServiceServer(s, &server)
  reflection.Register(s)

  go func() {
    if err := http.ListenAndServe(":8080", promhttp.Handler()); err != nil {
      log.Fatalf("failed to serve: %v", err)
    }
  }()

  if err := s.Serve(lis); err != nil {
    log.Fatalf("failed to serve: %v", err)
  }
}

The example above integrates Prometheus monitoring into your gRPC server and provides HTTP metrics for monitoring.

Implementation examples

Example 1: Microservice for order management

Let’s say we have an online store and we want to develop a microservice to manage orders. We can create a gRPC service with methods to create, view and update orders. This microservice can use Protocol Buffers to define messages, such as for orders and products. We should also provide monitoring using Prometheus and Grafana and logging using the ELK stack for debugging and performance analysis.

An example of gRPC service definition:

syntax = "proto3";

package ecommerce;

service OrderService {
  rpc CreateOrder (OrderRequest) returns (OrderResponse);
  rpc GetOrder (GetOrderRequest) returns (OrderResponse);
  rpc UpdateOrder (UpdateOrderRequest) returns (OrderResponse);
}

message OrderRequest {
  string user_id = 1;
  repeated Product products = 2;
}

message OrderResponse {
  string order_id = 1;
  string status = 2;
}

message GetOrderRequest {
  string order_id = 1;
}

message UpdateOrderRequest {
  string order_id = 1;
  string new_status = 2;
}

Example 2: A microservice for managing a tool

Let’s say we have another microservice for managing product inventory. We can create a gRPC service with methods to add, remove and update items in the inventory. This microservice also uses Protocol Buffers to identify messages and provides monitoring and logging for debugging.

An example of gRPC service definition:

syntax = "proto3";

package ecommerce;

service InventoryService {
  rpc AddProduct (AddProductRequest) returns (AddProductResponse);
  rpc RemoveProduct (RemoveProductRequest) returns (RemoveProductResponse);
  rpc UpdateProduct (UpdateProductRequest) returns (UpdateProductResponse);
}

message AddProductRequest {
  string product_id = 1;
  int32 quantity = 2;
}

message AddProductResponse {
  string product_id = 1;
  int32 new_quantity = 2;
}

message RemoveProductRequest {
  string product_id = 1;
}

message RemoveProductResponse {
  string product_id = 1;
}

message UpdateProductRequest {
  string product_id = 1;
  int32 new_quantity = 2;
}

message UpdateProductResponse {
  string product_id = 1;
  int32 new_quantity = 2;
}

Example 3: Authentication and authorization

To ensure the security of microservices, we may use an authentication and authorization mechanism. Let’s say we decide to use JWT for authentication. We add JWT token validation to our gRPC server and determine what roles and rights users have to ensure authorization.

An example of adding authentication to the GRPC server (in the Go language):

func main() {
  // Инициализация gRPC сервера
  // ...

  // Добавление аутентификации JWT
  interceptor := func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
    token, err := parseJWTFromContext(ctx)
    if err != nil {
      return nil, status.Errorf(codes.Unauthenticated, "Authentication failed: %v", err)
    }
    if !validateJWT(token) {
      return nil, status.Errorf(codes.PermissionDenied, "Permission denied")
    }
    return handler(ctx, req)
  }

  opts := []grpc.ServerOption{
    grpc.UnaryInterceptor(interceptor),
  }

  // Создание gRPC сервера с опцией аутентификации
  s := grpc.NewServer(opts...)

  pb.RegisterOrderServiceServer(s, &server)

  if err := s.Serve(lis); err != nil {
    log.Fatalf("failed to serve: %v", err)
  }
}

Conclusion

Microservice architectures and gRPC provide powerful tools for building scalable and robust applications. However, it should be remembered that the successful implementation of microservices requires not only technical skill, but also an understanding of business tasks and architectural solutions. Regional experts tell more about architectural solutions in practice in online courses at OTUS. Also, as part of each course, free lessons are held for which anyone can register. Here is a link to the nearest one:

Related posts