Agenda

Prerequisites:

• JDK 8
• IDE (prefered: Intellij Idea Comunity or Ultimate)
• git
• sdkman

We'll create a Spring Boot project from scratch.

• json endpoints
• embeded H2 database
• data repository
• dependency injection
• logging
• testing
• serving static files
• packaging (war, jar)
• profiles
• security
• deployment as linux service

Spring CLI

Install sdkman

sdk install springboot

spring init my-project

Empty project walkthrough

• pom.xml
• maven wrapper
• main class
• properties
• test

Just starts and exits - it's not a web server yet.
Spring Boot apps also can be:

• CLI
• batch
• GUI

git

git init

Note: there's already a `.gitignore'

Rename

• pom: artefect & group
• DemoApplication
• DemoApplicationTests
• package

Web

• pom.xml: spring-boot-starter-web (enable idea maven auto import)

@RestController
@SpringBootApplication
public class Application {

  @GetMapping("/")
  public String hello() {
    return "hello";
  }

  public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
  }
}

Postman

REST client.

Profiles

java -jar target/spring-project.jar --spring.profiles.active=dev

Deploing

• war on App Server
• Linux service
• Docker container

Linux service

mvn clean package -DskipTests

sudo cp ./spring.service /etc/systemd/system/ -i 
sudo useradd app
sudo mkdir -p /var/spring/
sudo cp target/spring-project.jar /var/spring/
sudo chown app:app -R /var/spring

sudo systemctl daemon-reload 
sudo systemctl start spring
sudo systemctl status spring

sudo systemctl enable spring # start at boot

View logs:

journalctl -u spring  
journalctl -fu spring # follow

Docker container

Build the image:

docker build -t spring-app .

Start the service:

docker service create -p 80:8080 --name spring-service spring-app

Optionally test (just run) the container:

docker run -it --rm -p 8080:8080 spring-app