JMHReif / microservices-level10

Microservices project - Spring Eureka for service discovery

Microservices Project: Level 10

This project is part of a series for creating microservices. In this repository, we use the following technologies:

• Spring Boot

• Java

• REST services

• Lombok

• Spring Data

• MongoDB document database

  • loaded with Book/Author domain data

• Docker and docker compose

• Neo4j AuraDB free tier

  • load with Book/Author/Review domain data

• Spring Cloud Config

• Spring Retry

• Spring Eureka (service discovery)

For the domain, we loaded a publicly-available UCSD Book Graph dataset that provides books and related information.

Architecture

We have 4 data services in this repository: service1, service2, service3, and service4. Responsibilities of each service are outlined below, followed by the changes to execution.

• Service1: backend service hosting the REST api for book data (MongoDB)

• Service2: client REST service for calling service1 and returning books

• Service3: backend service hosting the REST api for author data (MongoDB)

• Service4: backend service hosting the REST api for review data (Neo4j)

We also have a few supporting folders explained below.

• Config-server: application service to set up the config server managing database credentials for applications

• Data-neo4j: folder that includes steps and script for loading data set on books, authors, and reviews to Neo4j.

• Docker-mongodb: folder containing steps and data for starting and loading books and authors data to MongoDB Docker container.

• Eureka-server: application service to set up the service discovery for letting applications find and connect to one another.

• Microservices-java-config: holds sample YAML files containing database credentials. Note: Details on how to use the config are in this folder.

All of our services been packaged into Docker containers, and we are using Docker Compose to run and manage the services together.

Microservices functions

There are a variety of reasons businesses and users might choose to develop applications in a microservices architecture. Some potential reasons are listed below.

• Scalability

• Functionality independence (separating grouped features, often for reliability)

• Maintenance simplicity (changes only affect pieces, and less likely to impact whole)

• Shift resource load (from large instance running single monolith application, to many smaller instances hosting/coordinating microservices)

Executing the services

To reproduce this example, please follow the steps.

1. Clone this repository

2. Create a free Neo4j AuraDB instance and load data using the steps in the data-neo4j folder.

3. Build each Docker container (docker-mongodb, config-server, eureka-server, service1, service2, service3, service4). Note: if not on arm64 silicon chip, will also need to update Docker image names in compose file.

4. Execute Docker compose with docker-compose up -d.

5. Test the config server (MongoDB): Open a command line window and execute curl localhost:8888/mongo-client/docker.

6. Test backing service (books): Open a command line window and execute curl localhost:8081/db, curl localhost:8081/db/books, and curl localhost:8081/db/book/623a1d969ff4341c13cbcc6b.

7. Test backing service (authors): Open a command line window and execute curl localhost:8082/db, curl localhost:8082/db/authors, and curl localhost:8082/db/author/623a48c1b6575ea3e899b164.

8. Test the config server (Goodreads-client): Open a command line window and execute curl localhost:8888/goodreads-client/docker.

9. Test client service: Open a command line window and execute curl localhost:8080/goodreads and curl localhost:8080/goodreads/books.

10. Test the config server (Neo4j): Open a command line window and execute curl localhost:8888/neo4j-client/docker.

11. Test review backing service: Open a command line window and execute curl localhost:8083/neo, curl localhost:8083/neo/reviews or curl localhost:8083/neo/reviews/178186.

12. Verify all results! :)

Previous steps

• Level1 - Sending a string message from one Spring Boot app to another

• Level2 - Retrieving prepopulated Book data from one Spring Boot app to another

• Level3 - Storing Book data in MongoDB and retrieving all stored books

• Level4 - Adding new service for author data

• Level5 - Adding Docker compose to manage services as containers

• Level6 - Adding new service for review data (in Neo4j)

• Level7 - Adding Spring Cloud Config to manage Neo4j credentials

• Level8 - Adding MongoDB credentials to Spring Cloud Config

• Level9 - Adding Spring Eureka for Service Discovery