JibでJavaアプリを手軽にDockerコンテナ化してみる〜gradleでビルド、ローカルリポジトリに登録

$ sdk install springboot

package com.example.jibtest;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@RestController
public class DemoApplication {

    @RequestMapping("/")
    @GetMapping
    public String hello() {
        return "Hello World!";
    }

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

$ cd jib-test
$ ./gradrew bootRun

$ curl http://localhost:8080/
Hello World!

$ gradle jibDockerBuild
Tagging image with generated image reference jib-test:0.0.1-SNAPSHOT. If you'd like to specify a different tag, you can set the jib.to.image parameter in your build.gradle, or use the --image=<MY IMAGE> commandline flag.
warning: Base image 'gcr.io/distroless/java' does not use a specific image digest - build may not be reproducible

Containerizing application to Docker daemon as jib-test:0.0.1-SNAPSHOT...

Getting base image gcr.io/distroless/java...
Building dependencies layer...
Building resources layer...
Building classes layer...
Finalizing...
Loading to Docker daemon...
(以下略)

$ docker images | grep jib-test
jib-test            0.0.1-SNAPSHOT      2ce8c6f47c83        48 years ago        134MB

$ docker run -p 8080:8080 -it jib-test:0.0.1-SNAPSHOT 

$ curl http://localhost:8080/
Hello World!

$ docker exec -it 481fc8ea9d2a java -version
openjdk version "1.8.0_171"
OpenJDK Runtime Environment (build 1.8.0_171-8u171-b11-1~deb9u1-b11)
OpenJDK 64-Bit Server VM (build 25.171-b11, mixed mode)

$ docker exec -it 481fc8ea9d2a /bin/bash
OCI runtime exec failed: exec failed: container_linux.go:348: starting container process caused "exec: \"/bin/bash\": stat /bin/bash: no such file or directory": unknown

version = '0.0.2-SNAPSHOT'

./gradlew build -x test
(中略)
Containerizing application to Docker daemon as jib-test:0.0.2-SNAPSHOT...

Getting base image gcr.io/distroless/java...
Building dependencies layer...
Building resources layer...
Building classes layer...
Finalizing...
Loading to Docker daemon...

Container entrypoint set to [java, -cp, /app/libs/*:/app/resources/:/app/classes/, com.example.jibtest.DemoApplication]

Built image to Docker daemon as jib-test:0.0.2-SNAPSHOT

$ docker run -d -p 5000:5000 --restart always --name registry registry:2

$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
8378d3fa853c        registry:2          "/entrypoint.sh /etc…"   2 minutes ago       Up 2 minutes        0.0.0.0:5000->5000/tcp   registry

jib {
  allowInsecureRegistries = true
}

warning: Base image 'gcr.io/distroless/java' does not use a specific image digest - build may not be reproducible

Containerizing application to localhost:5000/jib-test-0.0.2...

Retrieving registry credentials for localhost:5000...
Getting base image gcr.io/distroless/java...
Building dependencies layer...
Building resources layer...
Building classes layer...
Finalizing...

Container entrypoint set to [java, -cp, /app/libs/*:/app/resources/:/app/classes/, com.example.jibtest.DemoApplication]

$ curl -X GET http://localhost:5000/v2/_catalog
{"repositories":["jib-test-0.0.1","jib-test-0.0.2"]}

$ docker run -p 8080:8080 -it localhost:5000/jib-test-0.0.2 

$ curl http://localhost:8080/
Hello World!