spring-cloud-microservice

Spring cloud microservices samples

Applications:

1. config-service: This application is a config server which is backed by GIT.
2. eureka-server: Service Discovery
3. example-service: Microservice 1 (example for config server and spring cloud bus)
4. example-service2: Microservice 2 (example for config server and spring cloud bus)
5. example-service3: Microservice 3 (example for Eureka server)
6. example-service4: Microservice 4 (example for Feign and Circuit breaker)
7. example-service5: Microservice 5 (Microservice which is used for translating word from English to French)
8. api-gateway: API Gateway (example for Spring Cloud Gateway)

Description

Spring Cloud config server testing

config-service: This application is a config server which is backed by GIT. It connects to https://github.com/jgpreetham/config/tree/master/config-data to retrieve the configurations for all the microservices The configuration yaml file name will be same as the microservice name (specified in application.yml of microservice)

example-service: This is microservice 1, which connects to config-server and retrieves the configurations of port number and value of someProperty

• Test it by hitting : http://localhost:8111/value -> this returns the value retrieved from config-server ( specified in example-service.yml file config.someProperty)

example-service2: This is microservice 2, which connects to config-server and retrieves the configurations of port number and value of someProperty

• Test it by hitting : http://localhost:8112/value -> this returns the value retrieved from config-server ( specified in example-service2.yml file config.someProperty)

Now update the properties in example-service and example-service2 in GIT

• Click on http://localhost:8111/refresh which will refresh the example-service ConfigProperties.java bean because this bean is annotated with @RefreshScope.

Now the example-service's someProperty would have the latest value. Test it by again hitting : http://localhost:8111/value

But example-service2 wouldn't have the latest property values. Test it by hitting : http://localhost:8112/value

In real world scenario there would be 100-1000 microservices and it's not practical to go and hit /refresh for all the services. So we would use spring-cloud-bus with amqp

Points to be noted

Pre-requsite: Docker should be installed Download RabbitMQ docker image: docker pull rabbitmq

Start the Rabbit MQ by running the following command:

 docker run -d --hostname my-rabbit --name some-rabbit -p 15762:15672 -p 5672:5672 rabbitmq:3-management

Test RabbitMQ by hitting URL http://localhost:15762/#/ .

Username: guest
Password: guest

Spring cloud Bus testing for dynamic updates

Now again restart your config server, example-service and example-service2.

• Test the value of example-service:http://localhost:8111/value
• Test the value of example-service2:http://localhost:8112/value
• Update the properties and hit : http://localhost:8888/bus/refresh

Now again, test the example-service and example-service2

• Test the value of example-service:http://localhost:8111/value
• Test the value of example-service2:http://localhost:8112/value

By hitting /refresh endpoint, all the microservices would be notified about the changes in GIT

Eureka Server testing

eureka-server: Service Discovery

Run exmaple-service3, exmaple-service4 and exmaple-service5, api-gateway and notice that all the services are shown on eureka portal : http://localhost:8761/

Feign testing

example-service4 uses Feign annotations to interact with example-service5

• By hitting http://localhost:8114/hello, feign would call example-service5 @GetMapping(value = "/translate/{word}").

Client Side load balancing testing

• Start 2 profiles(default and test) of example-service5. Hit http://localhost:8114/hello, feign would call example-service5 @GetMapping(value = "/translate/{word}") of different instances(default and test) automatically and you can verify by looking at the port number returned in the response.

Circuit Breaker testing

• Test circuit breaker by stopping example-service5 and hitting example-service4 http://localhost:8114/hello , this would go to fallback and give the result

API Gateway testing

• Start api-gateway service and hit http://localhost:8763/api-gateway/translate-service/hello which internally strips of the /api-gateway/translate-service/ and rewrites it as /example-service5/ and internally talks to eureka and goes to example-service5/hello to get the correct response and if you are running multiple instances of example-service5, it will load balance and you can verify by looking at the port number in the response.