spring-cloud-microservice-interaction

This repo contains four project.

Mainly these repos are created for demonstrating - "How do different microservices communicate with each other". Also, attempts have been made to introduce Spring boot and Docker..

Four submodules:

currency-exchange-service
currency-conversion-service
naming-server(eureka)
api-gateway(spring-boot-api-gateway)

Project setup

Download this repository

git clone --recursive https://github.com/khabib97/spring-cloud-microservice-interaction.git

Make submodules to track their respective remote branches (instead of being in detached HEAD state):

git submodule foreach -q --recursive 'git checkout $(git config -f $toplevel/.gitmodules submodule.$name.branch || echo master)'

Currency Exchange Service

Currency Exchange Service convert one currency to another currency. Conversion rates are stored in H2 database.

Clone currency-exchange-service repo
Import as maven porject
And run as java application
Creating multiple instance of this service, go Run Configurations -> Arguments(tab) -> Add VM arguments -Dserver.port=8001

http://localhost:8000/currency-exchange/from/EUR/to/BDT

Currency Conversion Service

Currency conversion service take an amount of currency and convet its value to another currency using Currency Exchange Service

Clone currency-conversion-service repo
Import as maven porject
And run as java application

http://localhost:8100/currency-conversion-feign/from/USD/to/BDT/quantity/10

Name Server

Naming server is created using netflix-eureka-server. Currency Exchange Service and Currency Conversion Service register them to Naming Server as eureka-client.

Using feign client currency conversion service calls currency exchange service.

It also perform client side load balancing

Clone naming-server
Import as maven porject
And run as java application

To view register services:

http://localhost:8761/

Api Gateway

Api gate way uses spring-boot-api-gateway. It gives an easy interface to talk with different microservices.

Now we can call Currency Exchange Service and Currency Conversion Service from:

http://localhost:8765/currency-exchange/from/EUR/to/BDT
http://localhost:8765/currency-conversion-feign/from/USD/to/BDT/quantity/10

Here we can convert modify our uri, implement authentication...

Clone api-gateway
Import as maven porject
And run as java application

Docker Version

Now we move to docker. Modifying our repositories so that we can run our services as containers.

For non docker version, after downloading set head to v1.0-non.dockerized tag

How to a create docker image?

In very sub-module, just add the below configuration in pom.xml file, inside build.plugins.plugin block:

<configuration>
	<image>
		<name>khabib97/${project.artifactId}:${project.version}</name>
	</image>
	<pullPolicy>IF_NOT_PRESENT</pullPolicy>
</configuration>

Then from eclipse, right click projct >> run as >> maven build... >> in Main tab's Goals >> add spring-boot:build-image -DskipTests [skipTests is not a good practice but for quicker image creating] >> run

It will create your docker image for that submodule. Create all submodule.

Zipkin and Rabbit MQ

Zipkin is used for Distributed Tracing
Incase of zipkin failure, rabbit mq is used for queueing

10000 feet architectural overview:

Run

After creating all images for the sub modules, run the docker-compose.yaml file,

$docker-compose up

It will up and run all containers(magic)
All previous url will be similar in that case.
Zipkins URL: http://127.0.0.1:9411/
Rabbit MQ URL: http://127.0.0.1:15672/

Kubernetes Version

Here we modify currency-exchange-service and currency-conversion-service in such a way, so that we can run it on kubernetes (Here Google Kubernetes Engine).

To get kubernetes version, checkout to kubernetes branch of these two repositories.

We remove cloud-starter-config, eureka, zipkin, redis from pom.xml
Then create image and upload image to dockerhub
Create cluster in GKE
Connect it to cloud console

$kubectl create deployment currency-exchange --image=khabib97/currency-exchange-service:0.0.2-SNAPSH

$kubctl expose deployment currency-exchange

$kubectl create deployment currency-conversion --image=khabib97/currency-conversion-service:0.0.2-SNAPSH

$kubctl expose deployment currency-conversion

Then go url and enjoy.

Try Local Kubernetes

Enable kunernetes from Docker application
Then use above command.
You can modify deployment.yaml and customized it
Using declarative approach by modifing deployment.yaml. you can replicate multiple deployment instances

$ kubectl get deployment currency-exchange -o yaml >> deployment.yaml
$ kubectl apply -f deployment.yaml

Special thanks to Ranga Rao Karanam for his tutorials