Service Architecture

This sample app is composed of manu microservices written in different languages that talk to each other over gRPC.

Services List

Service	Language	Description
frontend	Go	Exposes an HTTP server
productservice	Go	Provides the list of products
cartservice	Python	Stores the items in the user's shipping cart in Redis and retrieves it
checkoutservice	Node.js	Retrieves user cart, prepares order and orchestrates the payment and shipping detail
shippingservice	Java	(Not Ready Yet)

API Endpoint

Endpoint	Method	Description
/product	GET	Get all product catalog
/product/:id	GET	Get product with specific id
/cart/:userId	POST	Add cart item for specific user (detail below)
/cart/:userId	GET	Get cart item
/checkout/:userId	GET	Checkout process

Add Cart Params (form-data)

name : Name of Product

qty : Item quantity

curl --request POST   --url http://localhost:8080/cart/1   --data 'name=Xiaomi&qty=3'

Installation

Follow the instructions for installation process for each programming languages https://grpc.io/docs/quickstart/

Run Program

To run the application, run all services

go run services/product-service/server.go
node services/checkout-service/server.js
python3 services/cart-service/server.py
go run frontend/main.go

This app is running on port: 8080

Authentication

gRPC is supported authentication by default. And we will be using SSL/TLS authentication for the sake of simplicity.

1. Single TSL

The most easiest way is using single tsl which will be using to all services. To learn using single tls, checkout to branch auth/ssl

Creating SSL/TLS Certificates

mkdir ssl && cd ssl
openssl req -newkey rsa:2048 -nodes -keyout server.key -x509 -days 365 -out server.crt

Then try to run the application again

2. Mutual TLS

The second way is using mutual tls, this mean every service will have their own certificate, but all certificates generated from single root CA. To learn using Mutual TLS, checkout to branch auth/mutual-tls

certstrap will be our way to generate certificates.

Install certstrap

$ git clone https://github.com/square/certstrap
$ cd certstrap
$ ./build

Create a CA, server cert, and private key

$ bin/certstrap init --common-name "Root CA"
$ bin/certstrap request-cert --domain mydomain.com
$ bin/certstrap sign --CA "Root CA" mydomain.com
$ bin/certstrap request-cert --common-name localhost --ip 127.0.0.1 
$ bin/certstrap sign --CA "Root CA" 127.0.0.1

copy out/Root_CA.* to ssl directory in our project

copy out/localhost.* to directory : frontend/ssl

copy out/mydomain.* to directory : services/product-service/ssl

the project structure should look like this :

Protobuf Generator

Generate for Go

protoc -I proto/ proto/product-service.proto --go_out=plugins=grpc:services/product-service/proto/

Generate for Python

cd services/cart-service
python3 -m grpc_tools.protoc -I../../proto --python_out=. --grpc_python_out=. ../../proto/cart-service.proto