What is the best way to add a Circuit Breaker pattern in a Microservices Architecture. Should it be on the microservice side (inside each microservice), inside an ELB or insider the Api Gateway? What would be the best design pattern?
I think is not use in each microservice, but in your BFF (backend for frontend) who use microservice. You can find a good implementation and exemple in this book https://pragprog.com/book/mnee/release-it. Solution with API Gateway is good, see Kong https://getkong.org/ for that.
There are at least 3 options (illustrated below). In the general case, the circuit breaker "protects" calls to an http service. If we think this service is the microservice, the circuit breaker is never in the microservice itself.
API Gateway
In this case, you use an API gateway product that has circuit breaking support. Ambassador and Axway are examples. An alternative would be to provide circuit breaking in a BFF service that gets the calls to your backend service.
Service mesh
In this case, you use a service mesh product that has support for circuit breaking. Istio with Envoy are an example. In this example, the insurance quote service calls the customer history service. The proxy sidecar container does the circuit breaking.
Circuit breaker lib
Here you use a library that provides circuit breaker support. Resilience4J is the one we use at work (in some Spring Boot apps that call http services).
Your design
Which is best? It depends on your application requirements and infrastructure constraints. Things to remember:
Not all service interactions require circuit breaking.
See if a fallback mechanism (e.g., default response) can be used when the circuit is open.
Log/monitor circuit changes to detect problematic connections and services.
I would suggest you to delegate the circuit breaking concerns to a external library like Hystrix , rather than implementing it yourself.
Hystrix exposes a lot of properties that give you full control in tuning the circuit breaking capabilities.
Related
I think I understand what API Mgt is and Orchestration. E.g. SAP PO and SAP CPI allow Orchestration.
I was reading the following statement:
Modern applications and changes in protocols and message designs also
started to influence the ESB. A more lightweight integration components
started to emerge, known as the API Gateway. An API Gateway doesn't
have the overhead of adapters or the complex integration functionality
of the ESB but still allows encapsulation and provides the
management capabilities to control, secure manage and report on API
usage.
Reading this is all a little vague imho. The following:
Does an API Gateway not allow for Orchestration? I think it does, as AXWAY state this in https://www.axway.com/en/products/api-management/gateway. I guess my point is what does the phrase from above "An API Gateway doesn't
have the overhead of adapters or the complex integration functionality
of the ESB ...". That said, may be such products are doing this for microServices and for the REST APIs we need to use separate products?
E.g. having read https://www.redhat.com/en/topics/api/what-does-an-api-gateway-do it is unclear to me if orchestration of REST API's is possible with an API Gateway or if this is only for MicroServices possible?
SAP CPI is clearly Orchestration, but is it part of API Mgt or API Gateway? I think the latter.
When I look at Amazon API Gateway it states nothing about Orchestration.
I'm beginer to micro-services, so please help me out on this issue,
I'm working on simple micro service project with spring boot, zuul, hystrix and eureka. One of service calls data from another service. But when the service is down, response is 500, so it needs to be send request again to get the expected result.
But end user shouldn't it see. So is there a way to send a http request for the failed service again with zuul if the previous request is failed/short circuited.
Thanks in advance.
First for an unavailable service http code 503 is probably more suitable.
Then Zuul is an api gateway not a service mesh. I think you mix up both concepts here.
The goal of an api gateway is to accept traffic from outside your network and distributes it internally...and so abstract his complexity(it is actually a distributed facade/router).
Example: zuul, spring cloud gateway
A Service mesh acts as a proxy between microservices and bring on communications aspects like automatic retries, circuit breaker, tracing, logging.
Example Istio, Linkerd
But you can go without service mesh to implement this concern. Your caller microservice can protect itself by implementing timeout, retries and circuit breakers by embed a powerful library like resilience4j.(hystrix is actually at the end of his life)
This library will provide you an api allowing you to wrap communications with outside (other microservices) through a special proxy that will handle retries or/and circuit breakers for you.
You should have a look : https://github.com/resilience4j/resilience4
I'm exploring Istio's circuit breaker and wan't to setup fallback methods if the circuit trips.
I have a few Spring boot applications that are deployed on kubernetes and with Istio's circuit breaking defined in DestinationRule.
I can see that my caller application gets a 503 Service Unavailable exception when I intentionally bring down the called service.
I'm looking for design patterns or libraries with which I can define fallback methods for my rest calls,
something similar to #HystrixCommand.
I checked out spring-cloud-circuitBreaker but that doesn't support Istio.
I have also explored ClientHttpRequestInterceptor with Spring RestTemplate, and can catch all ServiceUnavailable exceptions, but I need a way to configure different fallback methods to different REST calls.
Any suggestion is appreciated.
For Example, I have two Rest Api services running
https://my-app-one.com/get
https://my-app-two.com/update
After Zuul API Gateway Implementation the requests will be routed to
Zuul Proxy:
Proxy 1 : https://zuul-api-gateway.com/get
Proxy 2 : https://zuul-api-gateway.com/update
Questions:
Can we implement Hystrix Dashboard at Zuul API gateway level?
Can we utilize all Hystrix commands if implemented at API gateway level?
What are the challenges and please provide documentation or examples.
I already have a working example of Hystrix Circuit Breaker and Hystrix Dashboard. All I want to know is if I can move Hystrix implementation at Zuul API gateway level.
#IMNash: Unfortunately, I cannot comment to your original question so I am afraid I have to ask you via an Answer. I am terribly sorry that I need to do that but I don't have enough reputation points yet.
Is it mandatory for you to go the Zuul way? If not, you might want to consider using Spring Cloud Gateway. The relevant post from Baeldung is an eye opener. See the below snippet:
//...route definition
.route(r -> r.path("/articles")
.filters(f -> f.hystrix("some-command"))
.uri("http://baeldung.com")
.id("hystrix_route")
I have tested this myself and yes, it's that easy to apply Hystrix.
The next step would be to configure the Hystrix filter as per your needs (e.g. timeouts, max semaphores, etc.).
I think we can only implement hystrix at individual rest service level. we can't implement hystrix at zuul routing level.
I have read few details of use of api gateway in microservices architecture. I have read that it basically helps with security , transformation , throttling etc. Is orchestration also one of it responsibilities? When I read about microservices , I saw that it should have dumb pipes and smart endpoints and services must be choreographed and not orchestrated. So my assumption is that orchestration is not a responsibility of api gateway.
Probably no orchestation but there is a pattern called API Gateway
Using an API Gateway
Usually a much better approach is to use what is known as an API
Gateway. An API Gateway is a server that is the single entry point
into the system. It is similar to the Facade pattern from
object-oriented design. The API Gateway encapsulates the internal
system architecture and provides an API that is tailored to each
client. It might have other responsibilities such as authentication,
monitoring, load balancing, caching, request shaping and management,
and static response handling. pattern call API Gateway
https://www.nginx.com/blog/building-microservices-using-an-api-gateway/
http://microservices.io/patterns/apigateway.html?utm_source=building-microservices-using-an-api-gateway&utm_medium=blog
https://www.nginx.com/blog/microservices-reference-architecture-nginx-proxy-model/