A simple example of microservices that is described in this series of blog posts.
There are two services:
-
RESTful service - exposes a REST API for registering a user. It saves the user registration in MongoDB and posts a message to RabbitMQ. It is the example code for the article Building microservices with Spring Boot - part 1.
-
Web application - implements the user registration UI and invokes the RESTful service. It is the example code for the article Building microservices with Spring Boot - part 2.
The services are written in Scala and use the following technologies.
- Spring Boot
- Spring Cloud
- Netflix OSS Eureka
- RabbitMQ
Note: There are other example microservice applications.
This project uses with Docker Compose to run the services as well as RabbitMQ and MongoDB.
The spring-boot-webapp project uses Selenium to test the web UI using the Chrome browser.
You will need to install ChromeDriver.
On Mac OSX you can run brew install chromedriver.
The quickest way to build and run the services on Linux/Mac OSX is with the following commands:
. ./set-env.sh
./gradle-all.sh assemble
docker-compose up -d
./show-urls.sh
Otherwise, follow these instructions.
The RESTful service uses RabbitMQ and MongoDB. The easier way to run them is to using Docker:
docker-compose up -d mongodb rabbitmq
You also need to set some environment variables so that the services can connect to them:
export DOCKER_HOST_IP=$(docker-machine ip default 2>/dev/null)
export SPRING_DATA_MONGODB_URI=mongodb://${DOCKER_HOST_IP}/userregistration
export SPRING_RABBITMQ_HOST=${DOCKER_HOST_IP}
This application uses Netflix OSS Eureka for service discovery. Build the Spring Cloud based Eureka server using the following commands:
cd eureka-server
./gradlew build
This application uses Zipkin for distributed tracing. Build the Zipkin server using the following commands:
cd zipkin-server
./gradlew build
Use the following commands to build the RESTful service:
cd spring-boot-restful-service
./gradlew build
You can run the service by using the following command in the top-level directory:
docker-compose up -d restfulservice
Once the service has started, you can send a registration request using:
./register-user.sh
You can examine the MongoDB database using the following commands
$ ./mongodb-cli.sh
> show dbs;
local 0.031GB
mydb 0.031GB
userregistration 0.031GB
> use userregistration;
switched to db userregistration
>
>
> show collections;
registeredUser
system.indexes
>
>
> db.registeredUser.find()
{ "_id" : ObjectId("55a99b0993860551c6020e9d"), "_class" : "net.chrisrichardson.microservices.restfulspringboot.backend.RegisteredUser", "emailAddress" : "[email protected]", "password" : "secret" }
> exit
$
Since the web application invokes the RESTful service you must set the following environment variable:
export USER_REGISTRATION_URL=http://${DOCKER_HOST_IP}:8081/user
Next, use the following commands to build the web application:
cd spring-boot-webapp
./gradlew build
Run the web application using the following command in the top-level directory:
docker-compose up -d web
You can access the web application by visiting the following URL: http://${DOCKER_HOST_IP?}:8080/register.html
There are also other URLs that you can visit. The following command will wait until the services are available and displays the URLs:
./show-urls.sh
The previous instructions deployed the services as Docker containers without actually packaging the services as Docker images.
The docker-compose.yml file ran the image java:openjdk-8u91-jdk and used volume mapping to make the Spring Boot jar files accessible.
Follow these instructions to build and run the Docker images.
You can build the images by running the following command:
./build-docker-images.sh
This script is a simple wrapper around docker build.
You can now run the Docker images using the docker-compose command with docker-compose-images.yml:
docker-compose -f docker-compose-images.yml up -d
The following command will wait until the services are available and displays the URLs:
./show-urls.sh