使用maven插件构建docker镜像并注册到nexus私仓

Maven是一个强大的项目管理和构建工具，下面我们介绍利用Maven插件构建Docker镜像并注册到Nexus私仓里面，这样，在服务器或者其它地方就可以直接拉取镜像并运行，这对服务共享或者服务器部署应用起到极大的方便。
在maven中央仓库，可以搜索到好几个docker-maven-pluging。

下面我们采用一款由Spotify公司开发的Maven插件docker-maven-plugin。

参考网址：
http://itmuch.com/docker/12-docker-maven/
https://blog.csdn.net/aixiaoyang168/article/details/77453974

快速入门

1.新建spring-cloud项目，eureka-server。

2.配置pom.xml文件：

<plugin>
    <groupId>com.spotify</groupId>
    <artifactId>docker-maven-plugin</artifactId>
    <version>1.2.0</version>
    <configuration>
        <imageName>my-image:${project.version}</imageName>
        <baseImage>java</baseImage>
        <entryPoint>["java", "-jar", "/${project.build.finalName}.jar"]</entryPoint>
        <!-- copy the service's jar file from target into the root directory of the image -->
        <resources>
            <resource>
                <targetPath>/</targetPath>
                <directory>${project.build.directory}</directory>
                <include>${project.build.finalName}.jar</include>
            </resource>
        </resources>
    </configuration>
</plugin>

插件配置说明：

imageName：指定镜像名称。一般是用仓库名称+实际名字作为镜像名称，如：docker-repo/my-image整个作为镜像名词，也可以直接用my-image作为镜像名称。冒号后面是镜像tag，如果不指定，则tag是latest,所以一般指定，就直接用maven项目的版本号。这里特别注意，tab不能带大写字母，否则报错。比如maven的版本号默认：0.0.1-SNAPSHOT。这样构建将会报错误。去掉SNAPSHOT。
baseImage：用于指定基础镜像，类似于Dockerfile中的FROM指令。这里用了java基础镜像，这是个集成了openJdk1.8的镜像，有643M那么大。因此，我们可以用这个替换hub.docker.com,只有127M大小，集成的jdk8。
entrypoint：类似于Dockerfile的ENTRYPOINT指令。
resources.resource.directory：用于指定需要复制的根目录，${project.build.directory}表示target目录。会在target目录下生成docker目录，jar包等生成在里面。
resources.resource.include：指定需要复制的文件。${project.build.finalName}.jar指的是打包后的jar包文件。

3.设置环境变量DOCKER_HOS

编辑/etc/profile文件，增加环境变量：

export DOCKER_HOST=tcp://192.168.33.10:2375

可能报错：

[ERROR] Failed to execute goal com.spotify:docker-maven-plugin:1.2.0:build (default-cli) on project demo: Exception caught: java.util.concurrent.ExecutionException: com.spotify.docker.client.shaded.javax.ws.rs.ProcessingException: com.spotify.docker.client.shaded.org.apache.http.conn.HttpHostConnectException: Connect to 192.168.33.10:2375 [/192.168.33.10] failed: Connection refused (Connection refused) -> [Help 1]

报错的话，把跳过该步骤，后面也能成功。待解……

ip是指本机ip。端口指定，不可更改。

4.启动docker引擎，执行下面命令开始构建：

mvn clean package docker:build

--查看是否生成镜像
docker image ls

5.启动镜像：

docker run --name eureka-server -p 8084:8084 -d my-image

可以正常访问网站啦！！

使用Dockerfile进行构建

<build>
  <plugins>
    ...
    <plugin>
      <groupId>com.spotify</groupId>
      <artifactId>docker-maven-plugin</artifactId>
      <version>VERSION GOES HERE</version>
      <configuration>
        <imageName>example</imageName>
        <dockerDirectory>docker</dockerDirectory>
        <resources>
           <resource>
             <targetPath>/</targetPath>
             <directory>${project.build.directory}</directory>
             <include>${project.build.finalName}.jar</include>
           </resource>
        </resources>
      </configuration>
    </plugin>
    ...
  </plugins>
</build>

基本不变，改成这个属性<dockerDirectory>docker</dockerDirectory> 。指定Dockerfile所在目录即可。然后也是执行mvn clean package docker:build就可构建了。

构建docker镜像并push到docker私服

简洁配置：

1.maven setting.xml配置：
添加：

<server>
   <id>my-docker-registry</id>
   <username>admin</username>
   <password>admin123</password>
   <configuration>
      <email>932852117@qq.com</email>
   </configuration>
 </server>

账号密码，是私服nexus的账号密码。

2.pom.xml配置：

<plugin>
    <groupId>com.spotify</groupId>
    <artifactId>docker-maven-plugin</artifactId>
    <version>1.2.0</version>
    <configuration>
        <imageName>119.145.41.171:8082/ymu-micr/my-image:${project.version}</imageName>
        <!-- <imageName>my-image:${project.version}</imageName> -->
        <baseImage>anapsix/alpine-java</baseImage>
        <entryPoint>["java", "-jar", "/${project.build.finalName}.jar"]</entryPoint> 
        <forceTags>true</forceTags>
        <!-- copy the service's jar file from target into the root directory 
            of the image -->
        <resources>
            <resource>
                <targetPath>/</targetPath>
                <directory>${project.build.directory}</directory>
                <include>${project.build.finalName}.jar</include>
            </resource>
        </resources>
        <serverId>my-docker-registry</serverId>
        <!-- <registryUrl>119.145.41.171:8082/v1/</registryUrl> -->
    </configuration>
</plugin>

3.执行命令构建上传到nexus私服：

mvn clean package docker:build -DpushImage

构建成功后可以在私服看到docker 镜像：

完整配置：

<plugin>
    <groupId>com.spotify</groupId>
    <artifactId>docker-maven-plugin</artifactId>
    <version>1.2.0</version>
    <configuration>
        <imageName>119.145.41.171:8082/ymu-micr/my-image:${project.version}</imageName>
        <!-- <imageName>my-image:${project.version}</imageName> -->
        <baseImage>anapsix/alpine-java</baseImage>
        <entryPoint>["java", "-jar", "/${project.build.finalName}.jar"]</entryPoint> 
        <forceTags>true</forceTags>
        <!-- copy the service's jar file from target into the root directory 
            of the image -->
        <resources>
            <resource>
                <targetPath>/</targetPath>
                <directory>${project.build.directory}</directory>
                <include>${project.build.finalName}.jar</include>
            </resource>
        </resources>
        <serverId>my-docker-registry</serverId>
        <!-- <registryUrl>119.145.41.171:8082/v1/</registryUrl> -->
    </configuration>
    <executions>
        <execution>
          <id>build-image</id>
          <phase>package</phase>
          <goals>
            <goal>build</goal>
          </goals>
        </execution>
        <execution>
          <id>tag-image</id>
          <phase>package</phase>
          <goals>
            <goal>tag</goal>
          </goals>
          <configuration>
            <image>my-image:${project.version}</image>
            <newName>119.145.41.171:8082/ymu-micr/my-image:${project.version}</newName>
          </configuration>
        </execution>
        <execution>
          <id>push-image</id>
          <phase>deploy</phase>
          <goals>
            <goal>push</goal>
          </goals>
          <configuration>
            <imageName>119.145.41.171:8082/ymu-micr/my-image:${project.version}</imageName>
          </configuration>
        </execution>        
    </executions>
</plugin>