如今容器使 Java 开发者比以往任何时候都更靠近“一次编写，随处运行” 的工作流程，但容器化 Java 应用却并非易事：你必须先编写 Dockerfile ，root 后运行 Docker 守护进程，等待构建完成，最后将镜像推送至远程注册表。

Jib 将处理将应用打包到容器镜像过程中的所有步骤，它直接与 Maven 和 Gradle Java 开发环境集成，不需要你编写 Dockerfile 或安装 Docker ，只需将其作为插件添加到你的构建中，就可以立即将 Java 应用容器化。

如下是Docker构建流程和Jib构建流程的区别，我们可以看到Jib构建相当简单，省去了Docker构建复杂的过程

Docker 构建流程：

Jib 构建流程：

Jib 提供了如下四种方式构建，我们今天使用Maven插件的方式来构建一下。

• Maven：请参阅有关jib-maven-plugin的文档。
• Gradle：请参阅文档jib-gradle-plugin。
• Jib Core：Java的通用容器构建库。
• Jib CLI：使用Jib Core构建图像的命令行界面

首先在springboot项目的pom.xml中添加jib插件，如下：

<plugin>
    <groupId>com.google.cloud.tools</groupId>
    <artifactId>jib-maven-plugin</artifactId>
    <version>2.6.0</version>
    <configuration>
        <from>
            <!--使用openjdk官方镜像，tag是8-jdk-stretch，表示镜像的操作系统是debian9,装好了jdk8-->
            <image>openjdk:8-jdk-stretch</image>
        </from>
        <to>
        <!--此处我设置的是推送到我的docker hub仓库-->
            <image>aimr0215/hellojib:${project.version}</image>
        </to>
    </configuration>
</plugin>

在pom.xml文件所在目录执行以下命令即可自动推送到 hub.docker.com，其中aimr0215是我在hub.docker.com上的注册账号，密码此处省略。填入你自己注册的账号密码即可。执行如下命令

mvn compile jib:build -Djib.to.auth.username=填写你的账号 -Djib.to.auth.password=填写你的密码

运行结果如下：

[INFO] Scanning for projects...
[INFO] 
[INFO] ------------------------< com.hzp:jib-project >-------------------------
[INFO] Building jib-project 0.0.1-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:3.1.0:resources (default-resources) @ jib-project ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] Copying 0 resource
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ jib-project ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- jib-maven-plugin:2.6.0:build (default-cli) @ jib-project ---
[WARNING] 'mainClass' configured in 'maven-jar-plugin' is not a valid Java class: ${start-class}
[INFO] 
[INFO] Containerizing application to aimr0215/hellojib:0.0.1-SNAPSHOT...
[WARNING] Base image 'openjdk:8-jdk-stretch' does not use a specific image digest - build may not be reproducible
[INFO] Using credentials from <to><auth> for aimr0215/hellojib:0.0.1-SNAPSHOT
[INFO] The base image requires auth. Trying again for openjdk:8-jdk-stretch...
[WARNING] The credential helper (docker-credential-desktop) has nothing for server URL: registry-1.docker.io
[WARNING] 
Got output:

credentials not found in native keychain

[WARNING] The credential helper (docker-credential-desktop) has nothing for server URL: registry.hub.docker.com
[WARNING] 
Got output:

credentials not found in native keychain

[INFO] Using credentials from Docker config (/Users/hzp/.docker/config.json) for openjdk:8-jdk-stretch
[INFO] Using base image with digest: sha256:d8d62fe0d8e9f3e6e62921c7d738c9a962efd6887b2b282dc2f852d7f1ee4512
[INFO] 
[INFO] Container entrypoint set to [java, -cp, /app/resources:/app/classes:/app/libs/*, com.hzp.jibproject.JibProjectApplication]
[INFO] 
[INFO] Built and pushed image as aimr0215/hellojib:0.0.1-SNAPSHOT
[INFO] Executing tasks:
[INFO] [==============================] 100.0% complete
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  03:02 min
[INFO] Finished at: 2020-11-24T18:00:07+08:00
[INFO] ------------------------------------------------------------------------

然后我们打开docker hub网站已经可以看到推送上去的镜像文件。

经过上述操作，一个项目的镜像文件就制作完成了。更多的操作可以参考jib官方github：

https://github.com/GoogleContainerTools/jib