Complete sample project with spring cloud using cloud config, eureka, zuul, feign, hystrix and turbine
1. Spring cloud config (taking out and putting all the properties file at the same location)
2. Eureka discovery enabled to maintain scaled up instances
3. API gateways with zuul to support routing to different microservice
4. Use of feign client to call different micro service wherever necessary
5. fallback support for feign
6. hystrix dashboard with turbine to get metrics
To start the project, first start config server, It is set up to be used in native mode, which menas it will search for the properties file specifically in local folder.
- Either you copy all the properties files from https://github.com/27rahulk/cloud-pet-project/tree/master/pet_profiles_config to the specified folder as shown in the pet-config application.properties path
spring.cloud.config.server.native.search-locations. It's configured to fetch from window location from Desktop, it can be modified at specific location. - Other way is by using a git location as commented out in application.properties file of pet-config
cd pet-config/
mvn spring-boot:run
cd pet-eureka/
mvn spring-boot:run
move to http://localhost:8761 to keep a track of registered server
cd cat-service/
mvn spring-boot:run
cd dog-service/
mvn spring-boot:run
cd pet-food/
mvn spring-boot:run
cd pet-api/
mvn spring-boot:run
cd pet-dashboard/
mvn spring-boot:run
UI/web --> pet-api --zuul--> cat and dog --feign--> pet-food
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pet-eureka
API gateway is the interface for web servers or browser. API gateway is running on 8080 and through API gateway all other services can be called.
API gateway uses zuul (@EnableZuulProxy) to route the calls to designated microserver
for example : GET http://localhost:8080/app/cat/sound gets routed to GET http://localhost:8070/cat/sound
hitting the API GET http://localhost:8080/app/cat/sound will give us "meooow!" response
similarly hitting API GET http://localhost:8080/app/dog/sound will be routed to dog service and will return "woof!"
Another caveat is when one micro service need to call to other micro service, it will use feign client (@EnableFeignClient). It can be demonstrated as when we call the api gateway to get cat food it routes the call to cat service which in turns makes a call to pet-food service to get cat food information.
GET http://localhost:8080/app/cat/food gets routed to GET http://localhost:8070/cat/food which makes a call to pet-food API http://localhost:8011/food/cat to get the information
If for some reason pet-food APIs are unavailable or it cannot be reached, we can configure a fallback implementation by providing @EnableCircuitBreaker and feign.hystrix.enabled=true
To test it, we can take down the pet-food service and try to make the call to http://localhost:8080/app/cat/food, it should show me the below message
food details is not available for cats at the moment! try again later.
We can keep a track of calls made by routing and circuit breaks by the means of hystrix dashboard, for that reason we would enable turbine (@EnableTurbine) in pet-dashboard running in localhost://8087 and @EnableHystrix in target services
To get the dashboard (@EanbleHystrixDashboard) make a call to http://localhost:8087/hystrix/
You should see the dashboard, in the stream put the value http://localhost:8087/turbine.stream and submit that, it should start monitoring and you should watch different services wuth chart and it should show the real time data when you try to make api calls of cat and dog.
A particular service metrics can be fetched by the call to the service for ex. - http://localhost:8080/actuator/hystrix.stream
GET /app/cat/sound
GET /app/cat/food
GET /app/dog/sound
GET /app/dog/food