Dockerfile java app

Goal

Create a Dockerfile to run a java app.

Steps

Step 1 : Create a simple endpoint

We create a simple endpoint /data that return some data.

@SpringBootApplication
public class DockerfileJavaAppApplication {

    private final Flux<Person> allPerson = Flux.just(
            new Person("Anthony", "Paris"),
            new Person("Celia", "Paris"),
            new Person("Thomas", "Marseille")
    );

    @Bean
    RouterFunction<ServerResponse> route() {
        return RouterFunctions.route()
                .GET("/data", serverRequest -> ServerResponse.ok().contentType(MediaType.APPLICATION_JSON)
                        .body(allPerson, Person.class))
                .build();
    }

    @Data
    @AllArgsConstructor
    @NoArgsConstructor
    class Person {
        String name;
        String city;
    }

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

Step 2 : Create the Dockerfile

FROM openjdk:15 Specify base image
ARG JAR_FILE=target/*.jar Create variable JAR_FILE referencing our jarfile
COPY ${JAR_FILE} app.jar Copy our jar file to the container and name it app.jar
EXPOSE 8080 Expose our server port (It's optional, but it's good to see what port our app will be using)
ENTRYPOINT ["java", "-jar", "/app.jar"] Launch our app when we start our container

FROM openjdk:15
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "/app.jar"]

Step 3 : Build the image with the Dockerfile

-t Tag our image

docker build -t avella/dockerfile-java-app:v1 .

We can see our created image by running the following command

docker image ls

Step 4 : Run the container

-d Detached mode
-p Publish port, forward incoming traffic from our local machine port 8080 to the container port 8080

docker run -d -p 8080:8080 --name dockerfile-java-app avella/dockerfile-java-app:v1

Step 5 : Test our endpoint

Go to our endpoint /data on the port we forwarded 8080 we should see some data.

[{"name":"Anthony","city":"Paris"},{"name":"Celia","city":"Paris"},{"name":"Thomas","city":"Marseille"}]

avella2409/dockerfile-java-app