（三）将容器变成镜像

提交保存镜像命令

docker commit <container> [repo:tag]

当我们在制作自己的镜像的时候，会在container中安装一些工具、修改配置，如果不做commit保存起来，那么container停止以后再启动，这些更改就消失了

一.通过命令来创建镜像

这种做法的优点：最方便最快速

缺点：不规范无法自动化

手动构建一个 myjava3的镜像过程如下：

[root@docker ~]# docker create --name myjava3 -it java /bin/bash
0814ffc5a92b66d017a620648205b1031b810ec1cb9da2ca411571dd75f4daac
[root@docker ~]# docker start myjava3
myjava3
[root@docker ~]# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
0814ffc5a92b        java                "/bin/bash"         20 seconds ago      Up 6 seconds                            myjava3

[root@docker ~]# docker exec -it 0814ffc5a92b /bin/bash
root@0814ffc5a92b:/#

root@0814ffc5a92b:/# ls
bin dev home lib64 mnt proc run srv tmp var
boot etc lib media opt root sbin sys usr

root@0814ffc5a92b:/# mkdir createimage

#退出容器提交保存镜像

root@0814ffc5a92b:/# exit
exit

[root@docker ~]# docker commit 0814ffc5a92b myjava3:v1.0
sha256:c7644e42d29b5938518e624ce8c1033ff8973d1b73501de7cc288c0f4dabbb76
[root@docker ~]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
myjava3 v1.0 c7644e42d29b 16 seconds ago 643MB

[root@docker ~]# docker run -it myjava3:v1.0 ls
bin createimage etc lib media opt root sbin sys usr
boot dev home lib64 mnt proc run srv tmp var

二.Buildfile自动化创建镜像

1.一个ubuntu下的Java镜像的buildfile

FROM nimmis/ubuntu:14.04
MAINTAINER nimmis <[email protected]>
# disable interactive functions
ENV DEBIAN_FRONTEND noninteractive
# set default java environment variable
ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64
RUN apt-get install -y software-properties-common && \
add-apt-repository ppa:openjdk-r/ppa -y && \
apt-get update && \
apt-get install -y --no-install-recommends openjdk-8-jre && \
rm -rf /var/lib/apt/lists/*

执行Dockerfile

[root@docker ~]# docker build -t benjamin/java .

2.Dockfile 复杂案例实战：制作ubuntu+java+tomcat+ssh server镜像

mkdir test
cd test
vi Dockfile
FROM ubuntu
MAINTAINER yongboy "[email protected]"
# 更新源，安装ssh server
RUN echo "deb http://archive.ubuntu.com/ubuntu precise main universe"> /etc/apt/sources.list
RUN apt-get update
RUN apt-get install -y openssh-server
RUN mkdir -p /var/run/sshd
# 设置root ssh远程登录密码为123456
RUN echo "root:123456" | chpasswd
# 添加orache java7源，一次性安装vim，wget，curl，java7，tomcat7等必备软件
RUN apt-get install python-software-properties
RUN add-apt-repository ppa:webupd8team/java
RUN apt-get update
RUN apt-get install -y vim wget curl oracle-java7-installer tomcat7
# 设置JAVA_HOME环境变量
RUN update-alternatives --display java
RUN echo "JAVA_HOME=/usr/lib/jvm/java-7-oracle">> /etc/environment
RUN echo "JAVA_HOME=/usr/lib/jvm/java-7-oracle">> /etc/default/tomcat7
# 容器需要开放SSH 22端口
EXPOSE 22
# 容器需要开放Tomcat 8080端口
EXPOSE 8080
# 设置Tomcat7初始化运行，SSH终端服务器作为后台运行
ENTRYPOINT service tomcat7 start && /usr/sbin/sshd -D