This example demonstrates how to build Curcuit Breaker pattern with Spring Cloud Eureka and Hystrix.
First build the projects, with maven:
mvn clean install
The MicroServices are going to open the port: 8761(Eureka Service discovery), 9080(A), 9081(B) and 9082(C)
Open 4 terminals, one for each component
cd eureka-server
java -jar target\circuit-breaker-boot-eureka-server-0.1.0-SNAPSHOT.jar
cd service-A
java -jar target\circuit-breaker-boot-service-A-0.1.0-SNAPSHOT.jar
cd service-B
java -jar target\circuit-breaker-boot-service-B-0.1.0-SNAPSHOT.jar
cd service-C
java -jar target\circuit-breaker-boot-service-C-0.1.0-SNAPSHOT.jar
Once all microservices lunched, open a browser to http://localhost:9080/serviceA/, you should get
{"ServiceA result" : "Welcome to Service A","ServiceC result" : "Welcome to Service C","ServiceB result" : "Welcome to Service B"}
in Browser.
When shutting down microservice B or C, it does not reply to the request anymore. The circuit breaker intercepts the error and execute a fallback. The circuit breaker will open after failed 5 times, If you restarts it, the output should be back to normal. This is because the circuit breaker tries periodically to reset its state and check whether or not things are back to normal.