A Case Study on Microservices with SpringBoot

The repository contains various project built to do a case study on "How to make microservices with Spring Boot? "

---

Concepts

What is a Service ?

A piece of software to provide a particular functionality to different software/components in the application.

What is a Microservice ?

Some salient features of a microservice are :

• A service oriented architecture done well
• Efficiently scalable application
• High performance application
• Single service with a single focus/functionality to deliver
• Technology agnostic API
• Lightweight communication
• Independent data storage
• Independently changeable and deployable

What is the need for a Microservice ?

• To respond to required changes quickly or adapt rapidly
• For reliability, as each microservice only has single functionality, they are less prone to errors
• Automated CI/CD is easier with smaller components
• On demand hosting technology like Cloud Foundry, Heroku, Azure, GCP
• Shorter development times
• Decoupling of changeable parts
• Faster issue resolutions

Characteristics of a Microservice

Highly Cohesive (Single Focus)	Autonomous (Self reliable on serving requests)	Business Domain Driven
Resiliency (able to serve with degraded func./ register -deregister)	Observable (monitoring, centralized logging)	Automation (CI/CD)

---

Technology Diagram

TODO List

• add basic flow diagram
• add various components in each service
• show how zuul,config and discovery come into play

---

Tools/Frameworks Used

1. Spring Boot - for rest api and various component development
   • Actuator - for application metrics
2. Spring Cloud
   • Cloud Config Server - for central configuration management
   • Cloud Config Client
   • Spring Slueth - for tracing of various downstream calls, health metrics of service
   • Cloud Bus - for refreshing configuration without restart
   • Eureka Dicsovery - for API hearbeat registry
   • Zuul API Gateway - For API proxy
3. Zipkin Server - to view tracing data in timeline view
4. Heroku - PAAS platform for deploying various applications
5. Travis - For auto build and deploy from github
6. LogDNA - For centralized logging from heroku

---

Status

Service	Description	API	Development	CI/CD
customer-service	api to retrieve customer details	link	Completed
item-service	api to retrieve item details like name, descp, cost etc.	link	Completed
sales-order-service	api to add order details to DB using customer-service & item-service for order validation	link	Completed
zipkin-server	zipkin ui to view request traceability	link	Completed
eureka-server	Eureka discovery server to register service health and available servers	link	Completed	❌ Pending
zuul-server	Provides proxy url for routing to all services	link	Completed	❌ Pending
config-server	Centralized configuration management for all components	link	Completed	❌ Pending

---

APIs

ms-customer-service

1.  http://localhost/api/customer/customer-service
2.  http://localhost/api/customer/customer-service/{emailId}

ms-item-service

1.  http://localhost/api/item/item-service
2.  http://localhost/api/item/item-service/{item names}

ms-sales-order-service

1.  http://localhost:8100/api/sales-order-service/order
    Request Sample : 
	{
	"orderDescription" : "test description",
	"orderDate" : "2018-06-04",
	"customerEmailId": "some.person@email.com",
	"itemNames" : [ "Item1","Item3" ]
	}
	
2.  http://localhost:8100/api/sales-order-service/orderId/1
	Response Sample : 
	{
    "orderId": 1,
    "customerEmailId": "some.person@email.com",
    "orderDescription": "test description",
    "orderDate": "2018-06-04T00:00:00.000+0000",
    "totalPrice": 400,
    "itemNames": [
        "Item1",
        "Item3"
   ]
   }

Issues Faced

1. Zuul not able to route request to proper host
2. Feign not able to pick correct server host from registry
3. Trace log not showing up in zipkin ui
4. Travis CI - Incorrect heroku key encryption