目的

由开发环境交测的时候，通过docker镜像简化环境搭建及项目部署的过程。

环境描述

项目开发环境: windowns7

在windowns7中通过VMware Workstation安装CentOS 7

在CentOS 7中安装docker

docker配置

1.docker正常安装。通过yum安装后最终信息如下：

[samhxm@localhost app]$ sudo docker version
Client:
Version:  1.12.3
API version:  1.24
Go version:   go1.6.3
Git commit:   6b644ec
Built:
OS/Arch:  linux/amd64
            
Server:
Version:  1.12.3
API version:  1.24
Go version:   go1.6.3
Git commit:   6b644ec
Built:
OS/Arch:  linux/amd64  

2.docker开启远程API。
通过yum安装的docker配置文件是/lib/systemd/system/docker.service
修改该文件的ExecStart参数为加入/usr/bin/dockerd -H TCP://0.0.0.0:2375 -H UNIX:///VAR/RUN/DOCKER.SOCK 最终配置如下：

[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network.target
        
[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/dockerd -H TCP://0.0.0.0:2375 -H UNIX:///VAR/RUN/DOCKER.SOCK
ExecReload=/bin/kill -s HUP $MAINPID
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
# Uncomment TasksMax if your systemd version supports it.
# Only systemd 226 and above support this version.
#TasksMax=infinity
TimeoutStartSec=0
# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes
# kill only the docker process, not all processes in the cgroup
KillMode=process
        
[Install]
WantedBy=multi-user.target   

3.重启docker

[samhxm@localhost ~]$ sudo systemctl daemon-reload
[samhxm@localhost ~]$ sudo systemctl restart docker

4.获取包含jre的基础镜像。如果仅仅是运行java程序，镜像中包含jre即可。我使用的是daocloud的java镜像。如果项目中需要其他环境依赖(数据库，MQ，Redis等)可以事先自行构建一个包含所需环境的镜像。

[root@localhost ~]# docker images
REPOSITORY                  TAG                 IMAGE ID            CREATED             SIZE
daocloud.io/library/java    latest              861e95c114d6        4 weeks ago         643.1 MB
daocloud.io/library/mysql   latest              cf725f136fd2        7 weeks ago         383.4 MB

maven项目pom.xml配置

在项目的pom.xml中加入docker-maven-plugin插件,根据项目实际情况进行设置。

<plugin>
    <groupId>com.spotify</groupId>
    <artifactId>docker-maven-plugin</artifactId>
    <version>0.4.13</version>
    <configuration>
        <dockerHost>http://192.168.1.107:2375</dockerHost>
        <imageName>sam/spring-boot-dockerimage</imageName>
        <baseImage>daocloud.io/library/java:latest</baseImage>
        <entryPoint>["java", "-jar", "/${project.build.finalName}.jar"]</entryPoint>
        <resources>
            <resource>
                <targetPath>/</targetPath>
                <directory>${project.build.directory}</directory>
                <include>${project.build.finalName}.jar</include>
            </resource>
        </resources>
     </configuration>
</plugin>

配置项说明：
dockerHost: docker宿主机地址，其中端口号为docker远程API访问端口。
imageName: 构建镜像的repository,该值勿包含英文大写字母。
baseImage: 基础镜像。基于该镜像构建项目的运行环境。
entryPoint: 同dockerfile中的命令，还可以写其他在dockerfile中运行的命令。
resources: 项目的资源配置

运行maven命令构建项目，并生成docker镜像

E:\workspace2\dockerImage>mvn clean package docker:build    

其中关键信息如下：

[INFO] Copying E:\workspace2\dockerImage\target\dockerimage.jar -> E:\workspace2\dockerImage\target\docker\dockerimage.jar
[INFO] Building image sam/spring-boot-dockerimage
Step 1 : FROM daocloud.io/library/java:latest
 ---> 861e95c114d6
Step 2 : ADD /dockerimage.jar //
 ---> d401cb3c9dfd
Removing intermediate container 49fcdc6cb81e
Step 3 : ENTRYPOINT java -jar /dockerimage.jar
 ---> Running in dd5ed0604906
 ---> a295878e59f6
Removing intermediate container dd5ed0604906
Successfully built a295878e59f6
[INFO] Built sam/spring-boot-dockerimage
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 24.871 s
[INFO] Finished at: 2016-12-10T17:18:55+08:00
[INFO] Final Memory: 29M/466M
[INFO] ------------------------------------------------------------------------

检查docker宿主机是否已产生镜像

[root@localhost ~]# docker images
REPOSITORY                    TAG                 IMAGE ID            CREATED             SIZE
sam/spring-boot-dockerimage   latest              804270c5ba56        7 seconds ago       658.9 MB
daocloud.io/library/java      latest              861e95c114d6        4 weeks ago         643.1 MB
daocloud.io/library/mysql     latest              cf725f136fd2        7 weeks ago         383.4 MB

启动镜像

[samhxm@localhost ~]$ sudo docker run -it -p 8080:8080 sam/spring-boot-dockerimage:latest /bin/bash

通过docker宿主机ip和8080端口即可访问项目。