Spring Boot Microservices

This repository contains an example of Microservices interaction using Spring Boot / Spring Cloud OpenFeing.

-The app is an Store Application which contains internally 3 Apps/Microservices ( Orders, Stock and Notifications ). The goal is to provide some REST APIs to manage Orders and Products.

-The main entry-point is the POST operation http://localhost:8081/orders/place-order associated to the Orders Microservice ( the POST method triggers the creation/placement of new Orders ).

-After call the previous POST operation, the Orders Microservice will call the Stock Microservice to check and decrement the stock availability of the requested Items.

-Finally, the Orders Microservice will persist into the database the new Order, and will call the Notifications Microservice to dispatch a 'New Order' notification email to the Customer (in case the SMTP email server it´s configured)

Rate Limiter and Circuit Breaker ( Microservices Design Patterns ) =>

-As an additional feature the Notifications Microservice it´s configured to use the Rate Limiter design pattern ( allows 1 request POST /send-new-order-notification every 10 seconds ) and the Stock Microservice it´s configured to use the Circuit Breaker design pattern ( will be triggered if an exception is produced over the endpoint GET /get-products )

🔧 Technology Stack

Java 17
Spring Boot 3 ( REST API )
Spring Cloud OpenFeign / Resilence4j
Spring Data ( MySQL )
Misc Libraries (  Maven  /  Docker  /  SpringDoc OpenAPI  /  Spring Email  /  Lombok  )

⚒️ Getting Started

# clone the project
git clone https://github.com/rodrigobalazs/springboot-microservices.git;

# start a mysql docker container associated to the Stock Microservice
docker run --name stock_db -e MYSQL_DATABASE=stock_db -e MYSQL_USER=user \
    -e MYSQL_PASSWORD=pass -e MYSQL_ROOT_PASSWORD=pass \
    -p 3306:3306 -d mysql:latest;

# make sure to update stock-microservice/src/main/resources/application.properties with
# the MYSQL_USER and MYSQL_PASSWORD defined in the previous point
spring.datasource.username=user
spring.datasource.password=pass


# start an additional mysql docker container associated to the Order Microservice
# note: the port has changed from 3306 to 3307 to avoid collisions between the docker DBs
docker run --name order_db -e MYSQL_DATABASE=order_db -e MYSQL_USER=user \
    -e MYSQL_PASSWORD=pass -e MYSQL_ROOT_PASSWORD=pass \
    -p 3307:3306 -d mysql:latest;

# make sure to update orders-microservice/src/main/resources/application.properties with
# the MYSQL_USER and MYSQL_PASSWORD defined in the previous point
spring.datasource.username=user
spring.datasource.password=pass

# <optional step> configure a Gmail account to act as the New Order notification 
# email SMTP server =>
-the Gmail account needs to have 2-Step verification (2FA) enabled
https://myaccount.google.com > search for App Passwords > create a new app "store_app" 
> copy the value of the generated <app_password>
-update notifications-microservice/src/main/resources/application.properties with =>
spring.mail.username=<gmail_used_to_generate_the_app>
spring.mail.password=<app_password>

# compile all the apps/microservices ..
cd springboot-microservices;
mvn clean install;

# starts the Stock microservice ..
cd stock-microservice; mvn spring-boot:run;

# starts the Order microservice ..
<open a new terminal window>
cd ../orders-microservice; mvn spring-boot:run;

# starts the Notifications microservice ..
<open a new terminal window>
cd ../notifications-microservice; mvn spring-boot:run;

💡 Orders Microservice ( API Examples )

1. Place a new Order =>

-Place a new Order based on the provided Quote details ( customer email + Items to purchase ).
This operation will also decrement the quantity in stock of the purchased Item(s) and will send a New Order email notification ( if configured )

curl -X POST http://localhost:8081/orders/place-order  \
     -H 'accept: application/json'  \
     -H 'Content-Type: application/json' -d \
'{
    "customerEmail": "somecustomer@emailtest.com",
    "items": [
        {
            "productName": "Rustic Sofa",
            "requestedQuantity": 2
        },
        {
            "productName": "Office Chair Flexi Seat",
            "requestedQuantity": 1
        }
    ]
}';

2. Retrieves all Orders =>

curl -X GET http://localhost:8081/orders/get-orders -H 'accept: application/json';

🔍 Orders Microservice ( API Documentation / Swagger )

http://localhost:8081/swagger-ui/index.html

💡 Stock Microservice ( API Examples )

1. Retrieves all Products =>

curl -X GET http://localhost:8082/stock/get-products -H 'accept: application/json';

2. Retrieves whether the requested quantity of the Product given as parameter is in Stock or not =>

curl -X GET "http://localhost:8082/stock/is-in-stock?productName=Rustic+Sofa&requestedQuantity=100" \
     -H 'accept: application/json';

3. Decrease the available quantity of the Product given as parameter =>

curl -X PUT "http://localhost:8082/stock/decrease-product-available-quantity?productName=Rustic+Sofa&quantityToDecrease=1" \
     -H 'accept: application/json';

💡 Stock Microservice ( how to test 'Circuit Breaker' )

In order to test whether the 'Circuit Breaker' works as expected over the Stock Microservice, modify StockController.java to force a RuntimeException =>

public ResponseEntity<List<Product>> getProducts() {
    throw new RuntimeException("forced exception to test whether the Circuit Breaker
         it´s being triggered as expected");
}

after that, execute this API endpoint =>

curl -X GET http://localhost:8082/stock/get-products -H 'accept: application/json';

-the IDE console should display a log trace similar to this one =>

c.r.n.c.StockController: Circuit Breaker has been triggered for Stock Microservice´s
StockController, proceed to execute circuitBreakerFallback() instead getProducts()

🔍 Stock Microservice ( API Documentation / Swagger )

http://localhost:8082/swagger-ui/index.html

💡 Notifications Microservice ( API Examples )

1. Sends a new Order Notification Email =>

curl -X POST "http://localhost:8083/emailNotifications/send-new-order-notification" \
     -d "customerEmail=somecustomer@emailtest.com" \
     -d "orderId=100" \
     -H 'accept: application/json';

💡 Notifications Microservice ( how to test 'Rate Limiter' )

In order to test whether the 'Rate Limiter' works as expected over the Notifications Microservice, execute 2 or more calls of this API endpoint in less than 10 seconds =>

curl -X POST "http://localhost:8083/emailNotifications/send-new-order-notification" \
     -d "customerEmail=somecustomer@emailtest.com" \
     -d "orderId=100" \
     -H 'accept: application/json';

-the IDE console should display a log trace similar to this one =>

c.r.n.c.EmailNotificationController: Rate Limiter has been triggered for Notifications
Microservice´s EmailNotificationController, proceed to execute rateLimiterFallback()
instead sendNewOrderNotification().

🔍 Notifications Microservice ( API Documentation / Swagger )

http://localhost:8083/swagger-ui/index.html