kparunsagar / springboot-single-image-docker-compose

Spring Boot Training Playground

Playground for the Spring Boot training.

Super simple 3 tier layer architecture Spring Boot application.

Including:

• Repository layer
  • Spring Data JPA
  • MySQL
  • Flyway (database migration)
• Service layer
  • Mapstruct to map object from the repository layer into a service layer object to not leak repository concerns into the other parts of the application.
• Rest API layer
  • Spring Web MVC

Prerequisites

• Java 11
• Docker (Desktop)

You don't need to have Maven installed. The project contains the Maven wrapper out of the box.

Build and run the project

./mvnw clean package

Start MySQL in a Docker container:

docker-compose up -d

Run the Spring Boot application using the Spring Boot Maven plugin.

./mvnw spring-boot:run

Exercises

• Play around with Spring Profiles
  • Introduce a profile like acceptance, production
  • Experience how property inheritance works
  • Configure the application differently for different profiles (like running Tomcat on a different port)
• Add Spring Boot test slices for every layer
  • Hints:
    • @DataJpaTest
    • @WebMvcTest
  • Make sure to fail the test first before you fix it ;)
• Testcontainers
  • Introduce more advanced repository layer integration tests
  • Replace H2
  • introduce test containers to run repository integration tests against a real MySQL instance running in Docker
• Introduce tests for the service layer
  • What to choose? Unit tests (Mockito) or integration tests?
  • If you choose to do integration tests make sure tests are not leaving traces behind in the database!
• AssertJ
  • Use this great library
  • Rewrite your assertions
  • Experiment with the fluent API try out to do assertions on collections
• Cloud native buildpacks
  • Build an OCI image for your Spring Boot application
  • Without using a Docker file
  • Add your Spring Boot Application OCI image to the docker-compose.yml
  • Start your Spring Boot application from Docker docker-compose up -d (you need to shut down the application first from your IDEA or Maven plugin)
  • Don't forget to configure the connection to the database because the application will not run inside a container ;)
  • Small hint see datasource configuration in: application.yml
• Archunit
  • Enforce your architecture rules
  • By creating some Archunit tests
  • Examples:
    • Service layer should be called only by the Rest layer
    • Repository layer should only be called by the service layer
  • Try to use some default archunit rules to enforce things like:
    • We don't use Jodatime in the project
    • We don't use the old Java data classes

Execute http calls to the rest API

IntelliJ http calls (Requires IntelliJ Ultimate)

You can also use curl:

Call the Spring Boot Info actuator

curl http://localhost:8080/actuator/info | jq

Call the Spring Boot Health actuator

curl http://localhost:8080/actuator/health | jq

Create a user

curl -XPOST  -d '{"userName":"Rod"}' -H "Content-Type: application/json" http://localhost:8080/api/users

Find a user

curl http://localhost:8080/api/users/1

Reference Documentation

For further reference, please consider the following sections:

• Official Apache Maven documentation
• Spring Boot Maven Plugin Reference Guide
• Create an OCI image
• Spring Web
• Spring Data JPA
• Flyway Migration