With regards to the Netflix Eureka Service Registry, I have setup the Eureka Netflix Server using Tomcat 8.0.35 successfully. I have also got the basic Example Service & Client to communicate with each other. I'm still new to Eureka and the management decision is to use Eureka with Spring as several new applications are written around the Spring framework.
I have been following the wiki in order to understand how the communication works (But with little to no success with registering services).. Eureka Github Wiki.
My question is: Do I need to create my own Eureka Service & Client in order to maintain a registry of about 50 cloud instances? (If so, can you please point me in the right direction).
I have hands on experience with Consul/RESTfull API, and have implemented Consul in production (using php, and qbit); however the Netflix Eureka Registry look's as though I need to learn eureka/spring + client/server java programming? I'm still getting used to the following terms.
Eureka Server (I successfully got this working using Tomcat8/JDK1.8 + the eureka.war)
Eureka Service (Some kind of stand-alone RESTfull service that queries the Eureka-Server and listens for client requests)
Eureka Client (Java snippet to be embedded into the Java servlets/jsp)?
Zuul (A type of routing/load-balancing app - similar to HaProxy ?)
Ribbon (A type of routing/load-balancing app - similar to HaProxy ?)
I would like to get the Service & Client configured for mostly non-AWS cloud instances. The Eureka Wiki is not very helpful when it comes to creating a working eureka service & client. Any help to point me in the right direction to implement a Eureka based RESTfull system would be helpful.
I suggest you to read this documentation about spring-cloud : http://cloud.spring.io/spring-cloud-static/spring-cloud.html
It should be a good start to setup a few simple spring-boot/spring-cloud services and start to use advanced tools like zuul/ribbon/hystrix ...
There is a simple example of distributed system using Spring Boot and Spring Cloud Netflix.
This project contains the following microservices:
requestor and responder which communicates via REST/HTTP
gateway microservice - Spring Boot app + Zuul
discovery microservice - Spring Boot app + Eureka
Moreover, requestor microservice uses Hystrix library.
As you can see, Spring Cloud provides a really good wrapper for Netflix solutions. As a result, you can start quickly with minimal configuration.
Related
The setup:
I have a set of Spring Boot based microservices that are fronted by Spring Cloud Gateway, meaning every request that comes from UI or external API client first comes to Spring Cloud Gateway and is then forwarded to appropriate microservice.
The routes are configured in Consul, and Spring Cloud Gateway communicates with Consul to get the routes accordingly.
Requirement:
There is a need of some microservices communicating with each other with REST APIs. I would prefer this communication to happen via the Spring Cloud Gateway as well. This will help in reducing multiple services going to Consul for getting other service's details.
This means every service should know Gateway's detail at least. And there can be multiple instances of Gateways as well. How is this dealt with in bigger architectures?
Any example that I look up contains one service using Consul, or Gateway using the consul with one microservice. Couldn't understand how to extrapolate that design to a bigger system.
I am trying to build a simple application with microservices architecture.
Below are the details about 3 microservices I have created.
1] Customer.
database: mongodb
server : embeded tomcat server.
port : 8081
2] vendor.
database: mongodb
server : embeded tomcat server.
port : 8082
3] product.
database: mongodb
server : embeded tomcat server.
port : 8083
All the 3 micros runs on an embeded tomcat server.
Now I want to create a common gateway for all these micros [API gateway].
which help me to route my request based on the request I get for example:-
for example if I get a request of http://hostname:port_of_gateway/customer.
on reading this I need to route the request tom my customer micro and fetch its response and send it back to client.
Which of the spring tool I can use to achieve this?
Because your requirements are quite simple you can implement such a gateway by yourself. Here's an example.
But if you really want to use some Spring solution you can try to use Spring Cloud Netflix which is a part of Spring Cloud umbrella project. It includes router and filter features which in turn based on Netflix Zuul gateway service.
Note that this is not a complete standalone application but a library. Therefore you still should create another microservice that would act as API gateway in your application. To make it a gateway you should just add #EnableZuulProxy annotation to the same class that has #SrpingBootApplication annotation. You can find a very good example here.
Please also note that you should somehow inform the gateway about your microservices' addresses for redirection. It can be done in two general ways:
By statically defining the addresses in gateway microservice's configuration;
By applying service discovery pattern in conjunction with e.g. Netflix Eureka service registry.
The 1st approach is easy and straightforward but is not very well for large number of microservices and/or when microservices' locations can change dynamically (e.g. due to auto-scaling).
The 2nd approach requires additional component - service registry - and needs modification of other microservices (to let them register themselves in the registry). This is quite more complicated approach but is the only possible in case of complex architecture. Simple yet expressive example can be found in the same article.
UPDATE (January'19)
As of December 2018 the Spring Cloud team announced that almost all Netflix components in Spring Cloud (except Eureka) entered maintenance mode. It means that for the next year they won't receive any feature updates (only bugs and security fixes).
There are replacements for all the affected components, including Netflix Zuul aforementioned above. So please consider using Spring Cloud Gateway instead of it in new projects.
I am creating a simple project in microservices using spring boot and netflix OSS to get my hands dirty. I have created two services
config service which has to register itself in discovery(eureka)
service.
discovery service which requires config service to be running to get its configuration.
Now when I am starting these services, both services fails due to inter dependency. What are the best practices resolve this issue and which one to start first.
PS:- I know I am creating circular dependency, But what is the way to deal with situation like this where I want to keep eureka configuration also with the config server
Thanks
I believe that you can find the answer for your question in the official spring cloud config server documentation:
Here: http://cloud.spring.io/spring-cloud-config/spring-cloud-config.html#_spring_cloud_config_client
Basically you have to choose between a "Config First Bootstrap" or "Discovery First Bootstrap".
From the docs:
"If you are using a `DiscoveryClient implementation, such as Spring Cloud Netflix and Eureka Service Discovery or Spring Cloud Consul (Spring Cloud Zookeeper does not support this yet), then you can have the Config Server register with the Discovery Service if you want to, but in the default "Config First" mode, clients won’t be able to take advantage of the registration.
If you prefer to use DiscoveryClient to locate the Config Server, you can do that by setting spring.cloud.config.discovery.enabled=true (default "false"). The net result of that is that client apps all need a bootstrap.yml (or an environment variable) with the appropriate discovery configuration. (...)"
I have one monolith spring web application developed using spring 3.1 and spring-security 3.1 with Java 7 and it is deployed on tomcat 7.
Now I have a new requirement where I have to create a micro-service for a new module using spring boot with java 8. This micro-service will be deployed separately on different EC2 instance.
I am looking for suggestion/idea to access new microservice from my existing spring web application.
How to perform inter process communication within these two spring application?
Can someone provide me any help/pointer?
You can make use of service discovery pattern, which are mainly of two kinds -
Client-side discovery - This is where clients are responsible for figuring out available service instances. Example - Netflix OSS.
Server-side discovery - In this the service instances are registered on the server-side using a service registry. Example - AWS ELB.
You can read a lot about these on the internet. Just remember the keywords.
Hope this helps !
Is Spring cloud config server an example of sidecar application for microservices?
Do you mean if the Spring Cloud Config Server itself is what the Spring Cloud documentation labels as Sidecar? Then no, as far as I know it is just a plain, regular Spring Boot app.
A Sidecar as referred to in Polyglot support with Sidecar is a Spring Boot application that acts as a bridge between your service infrastructure and a service that is not written in a JVM language. Apps written in Python, Go, Ruby, C#, NodeJS, Erlang or really any other language that can bind something to a port come to mind.
The benefits of the Sidecar are, that your Non-JVM apps
service discovery become automatically discoverable through Eureka, which means that JVM services can resolve the host:port/<service-id> of the Non-JVM apps as well as the other way around,
monitoring are monitorable through the same health-endpoints-infrastructure that is available in Spring Boot (Actuator), i.e. by manually providing the health endpoint in the Non-JVM app Eureka knows when the Non-JVM service is down
routing/proxying query the services by either manually looking up their hosts/ports or proxying these requests through Zuul, which in turn resolves their current addresses through Eureka
balancing be load balanced by Ribbon and
configuration may consume configuration properties provided via Spring Cloud Config.
I hope this answer addresses your question, if not (or someone finds it to be inaccurate or misleading) just let me know and I delete it to make room for something more suitable. ;-)