Learning series: Backend API in JAVA

Sample backend API. The goal is to exercise key concepts using JAVA 14, Spring Boot, Junit 5.

My Next Book

Context

Sample RESTful API to manage a book catalog.

Technical Details

Languages and Frameworks

• Java 14

• Spring Boot: Many guides on building restful services are provided there

• Spring Start: Spring Initializer tool

• RESTful communication with JSON resources

• Database

  • Local: h2 in memory database. Console is enabled for further details at: http://localhost:8080/h2-console
  • Upper environments: Postgres

• Infrastructure: to be defined

Testing Stack

• JUnit, Mockito, RestAssured for testing
• ArchUnit to test your code design
• Gradle to manage your dependencies
• Docker

Local Environment

Running the Application Locally

Locally the application is running with an H2 database and a volatile memory defined at:

Using gradle wrapper

• Navigate to your root application directory and then run:

$ ./gradlew bootRun

• Run with specific profile

$ ./gradlew bootRun --args='--spring.profiles.active=PROFILE  '

Building local docker image

• Build the application (please notice that the application name and version may vary):

$ ./gradlew build && java -jar build/libs/catalog-0.0.1-SNAPSHOT.jar

• Generate the application docker image:

$ mkdir -p build/dependency && (cd build/dependency; jar -xf ../libs/*.jar)
$ docker build --build-arg DEPENDENCY=build/dependency -t catalog/my-next-book-docker .

• Run the application:

$ docker run --name=books -d -p 8080:8080 catalog/my-next-book-docker

• Alternatively you can override the Spring active profile by running the container with:

$ docker run -e "spring.profiles.active=PROFILE" --name=books -p 8080:8080 catalog/my-next-book-docker

The application is then available on http://localhost:8080

• When it is running you can see in the list of containers, e.g:

$ docker ps

• Stop the container:

$ docker stop books

Setup Local Postgres

Let's see how to

• Create volume to store data

$ docker create -v /var/lib/postgresql/data --name PostgresData alpine

• Create database

$ docker run -p 5432:5432 --name postgres -e POSTGRES_PASSWORD=<define a password> -d --volumes-from PostgresData postgres

Further reference

• HATEOS