windows打包java docker镜像，无需启动docker服务

打包原理

使用google的 jib 工具
jib使用java实现了docker镜像的打包功能，所以能够跨平台打包

gradle + jib插件使用

1. build.gradle 添加插件

plugins {
    id 'org.springframework.boot' version '2.1.4.RELEASE'
    id 'io.spring.dependency-management' version '1.0.9.RELEASE'
    id 'java'
    id "com.google.cloud.tools.jib" version "2.6.0"
}

2. 添加jib配置

jib {
    from {
        image = "adoptopenjdk/openjdk11:alpine-jre"
    }
    to {
        image = "dingsync:latest"
    }
    container {
        entrypoint = ["sh", "-c", "chmod +x /entrypoint.sh && sync && /entrypoint.sh"]
        ports = ["8082"]
        environment = [
                SPRING_OUTPUT_ANSI_ENABLED: "ALWAYS",
                JHIPSTER_SLEEP: "0",
                JAVA_OPTS:"-Dspring.profiles.active=dev"
        ]
    }
    allowInsecureRegistries = true
}

3. 添加entrypoint.sh

记得要修改主类的名字,entrypoint.sh 放在项目 src/main/jib 文件夹下

#!/bin/sh
echo "The application will start in ${JHIPSTER_SLEEP}s..." && sleep ${JHIPSTER_SLEEP}
exec java ${JAVA_OPTS} -noverify -XX:+AlwaysPreTouch -Djava.security.egd=file:/dev/./urandom -cp /app/resources/:/app/classes/:/app/libs/* "vip.youngboy.dingsync.DingsyncApplication"  "$@"

打包镜像命令

gradlew jib //打包并推送参考
gradlew jibBuildTar  //打tar包
gradlew jibDockerBuild //打包并运行

maven + jib使用

详见 https://github.com/GoogleContainerTools/jib

maven配置

<plugin>
                <groupId>com.google.cloud.tools</groupId>
                <artifactId>jib-maven-plugin</artifactId>
                <version>2.7.0</version>
                <configuration>
                    <from>
                        <image>adoptopenjdk/openjdk11:alpine-jre</image>
                    </from>
                    <to>
                        <image>${docker.repostory}/${docker.registry.name}/${project.artifactId}</image>
                        <tags>${profiles.active}</tags>
                    </to>
                    <container>
                        <entrypoint>
                            <entry>sh</entry>
                            <entry>-c</entry>
                            <entry><![CDATA[chmod +x /entrypoint.sh && sync && /entrypoint.sh]]></entry>
                        </entrypoint>
                        <ports>11330</ports>
                        <environment>
                            <SPRING_OUTPUT_ANSI_ENABLED>ALWAYS</SPRING_OUTPUT_ANSI_ENABLED>
                            <JHIPSTER_SLEEP>0</JHIPSTER_SLEEP>
                        </environment>
                    </container>
                    <allowInsecureRegistries>true</allowInsecureRegistries>
                </configuration>
            </plugin>

进阶

Q:为什么不使用打成jar包，而是使用 java -cp的方式启动？

A: 打成jar包会导致不能缓存依赖jar包，每次需要上传的文件就会变大，如果把lib分离出来就可以把lib单独作为一个layer层