# Blockchain Microservice

# **Microservices with Ignite CLI Tutorial**

## **Introduction**

In this tutorial, we'll explore how to structure a blockchain application using Ignite CLI in a microservices architecture. We'll integrate blockchain modules as independent microservices that can interact with existing services or other blockchain modules.

## **Prerequisites**

- Ignite CLI installed on your system.
- Basic understanding of microservices architecture.
- Docker and Docker Compose for containerization and orchestration.

## **Overview of Steps**

1. **Define Microservices Architecture**: Determine which components of your blockchain application can function as independent services.
2. **Scaffold Blockchain Modules**: Use Ignite CLI to scaffold modules that will become microservices.
3. **Containerize Services**: Create Dockerfiles for each service and define service orchestration with Docker Compose.
4. **Set Up Communication**: Implement communication between services using REST APIs, gRPC, or messaging queues.
5. **Integrate with Existing Microservices**: Link your blockchain microservices with existing non-blockchain microservices.

## **Step-by-Step Guide**

### **Step 1: Define Microservices Architecture**

Identify components of your blockchain that can operate independently. For example:

- A token management service
- A user authentication service
- A smart contract execution service

### **Step 2: Scaffold Blockchain Modules**

Use Ignite CLI to scaffold modules for each identified microservice. For example:

ignite scaffold module tokenmanagement --dep bank
ignite scaffold module userauth
ignite scaffold module smartcontracts

### **Step 3: Containerize Services**

For each microservice, create a Dockerfile. Here's an example Dockerfile for the **`tokenmanagement`** service:

# Dockerfile for tokenmanagement service
FROM golang:alpine

# Set working directory
WORKDIR /app

# Copy the source code
COPY . .

# Build the blockchain node
RUN ignite chain build

# Expose necessary ports
EXPOSE 1317 26656 26657

# Command to run the blockchain node
CMD ["./build/tokenmanagementd"]

Define the orchestration for all services in a **`docker-compose.yml`** file:

version: '3.8'
services:
  tokenmanagement:
    build: ./tokenmanagement
    ports:
      - "1317:1317"
      - "26656:26656"
      - "26657:26657"

  userauth:
    build: ./userauth
    ports:
      - "1318:1317"

  smartcontracts:
    build: ./smartcontracts
    ports:
      - "1319:1317"

### **Step 4: Set Up Communication**

Implement API gateways or messaging systems that allow microservices to communicate with each other and external clients. For RESTful communication, define routes and handlers. For gRPC, define service interfaces and implement the server and client stubs.

### **Step 5: Integrate with Existing Microservices**

If integrating with non-blockchain microservices, ensure your blockchain microservices can communicate through established protocols and adhere to the existing ecosystem's standards.

For instance, if you have a payment processing microservice outside of your blockchain environment, you would provide API endpoints in your **`tokenmanagement`** service for interaction:

// tokenmanagement/api.go
func RegisterRoutes(router *gin.Engine, k tokenmanagement.Keeper) {
    router.POST("/payments", func(c *gin.Context) {
        // Logic to interact with external payment processing service
    })
}

## **Conclusion**

By the end of this tutorial, you will have a set of independently scalable and maintainable microservices that form a cohesive blockchain application, potentially integrated with an existing microservices architecture.