Multi-Microservice Go E-commerce Application

The project consists of the following main components:

• Account Service
• Catalog Service
• Order Service
• GraphQL API Gateway

Each service has its own database:

• Account and Order services use PostgreSQL
• Catalog service uses Elasticsearch

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Getting Started

1. Clone the repository:

   git clone <repository-url>
   cd <project-directory>
   

2. Start the services using Docker Compose:

   docker compose up
   

3. Access the GraphQL playground at http://localhost:8000/playground

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Tech Stack

• Go – Core backend language for all microservices
• gRPC – Fast and type-safe service-to-service communication
• GraphQL – Centralized API gateway
• Docker – Containerization of services
• Docker Compose – Local orchestration
• PostgreSQL – Relational data storage

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Command to Generate Protobuf Files

To generate Go code from your .proto files, run:

protoc --go_out=./pb --go-grpc_out=./pb account.proto

Install protoc

To install protoc:

brew install protoc

Required Extensions

You need these plugins installed:

• protoc-gen-go
• protoc-gen-go-grpc

How to Install

Run these commands:

    go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
    go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest

Make sure your Go binaries path is in your PATH environment variable. Add this line to your shell profile (~/.bashrc or ~/.zshrc):

    export PATH="$PATH:$(go env GOPATH)/bin"

Reload your shell or run source ~/.bashrc (or your profile) after adding the line.

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Now protoc can find the plugins and generate Go and gRPC code correctly.

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GraphQL API Usage

The GraphQL API provides a unified interface to interact with all the microservices.

Query Accounts

query {
  accounts {
    id
    name
  }
}

Create an Account

mutation {
  createAccount(account: {name: "New Account"}) {
    id
    name
  }
}

Query Products

query {
  products {
    id
    name
    price
  }
}

Create a Product

mutation {
  createProduct(product: {name: "New Product", description: "A new product", price: 19.99}) {
    id
    name
    price
  }
}

Create an Order

mutation {
  createOrder(order: {accountId: "account_id", products: [{id: "product_id", quantity: 2}]}) {
    id
    totalPrice
    products {
      name
      quantity
    }
  }
}

Query Account with Orders

query {
  accounts(id: "account_id") {
    name
    orders {
      id
      createdAt
      totalPrice
      products {
        name
        quantity
        price
      }
    }
  }
}

Advanced Queries

Pagination and Filtering

query {
  products(pagination: {skip: 0, take: 5}, query: "search_term") {
    id
    name
    description
    price
  }
}

Calculate Total Spent by an Account

query {
  accounts(id: "account_id") {
    name
    orders {
      totalPrice
    }
  }
}

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Access Elastic Search for Catalog DB

After the app is up and running, ElasticSearch DB can be accessed at:

    http://localhost:9200

To check all indices visit:

http://localhost:9200/_cat/indices?v

To check all documents in the catalog index:

http://localhost:9200/catalog/_search?pretty

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Access Postgres for Account DB

PostgreSQL can be accessed and used via CLI (Command Line Interface) After the app is up and running, in the terminal follow the below commands:

docker exec -it <container_id_for_accountDB> psql -U <db_username> -d <db_name>

Once you are in the PostgreSQL CLI, use the following commands:

To view tables:

 \dt

To view accounts information:

SELECT * FROM accounts;

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Access Postgres for Orders DB

PostgreSQL can be accessed and used via CLI (Command Line Interface) After the app is up and running, in the terminal follow the below commands:

docker exec -it <container_id_for_orderDB> psql -U <db_username> -d <db_name>

Once you are in the PostgreSQL CLI, use the following commands:

To view tables:

 \dt

To view orders information:

SELECT * FROM order;

To view ordered products information:

SELECT * FROM order_products;