Dockerfile prepared and packaged in the mirror - Docker container

A, commit mirror package

We ubuntu mirroring an example:
First, there is a mirror image of ubentu

[root@server1 ~]# docker images ubuntu
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
ubuntu              latest              07c86167cdc4        3 years ago         188MB

We first establish vm1 container, and do some operation, then ctrl + p + q quit

[root@server1 ~]# docker run -it --name vm1 ubuntu
root@6074aca22100:/# ls
bin   dev  home  lib64  mnt  proc  run   srv  tmp  var
boot  etc  lib   media  opt  root  sbin  sys  usr
root@6074aca22100:/# touch file{1..10}
root@6074aca22100:/# ls
bin   etc     file2  file5  file8  lib    mnt   root  srv  usr
boot  file1   file3  file6  file9  lib64  opt   run   sys  var
dev   file10  file4  file7  home   media  proc  sbin  tmp

Whether on the basis of the above we remove vm1 container, and then re-create, view documents created there

[root@server1 ~]# docker rm -f vm1
vm1
[root@server1 ~]# docker run -it --name vm1 ubuntu
root@94a7b7a6ffc0:/# ls
bin   dev  home  lib64  mnt  proc  run   srv  tmp  var
boot  etc  lib   media  opt  root  sbin  sys  usr

We can not find the file we created, our operations have not been saved.
So we need to let it continue to exist if it is necessary to re-establish and re-commit to the package

root@94a7b7a6ffc0:/# touch file{1..10}
root@94a7b7a6ffc0:/# ls
bin   etc     file2  file5  file8  lib    mnt   root  srv  usr
boot  file1   file3  file6  file9  lib64  opt   run   sys  var
dev   file10  file4  file7  home   media  proc  sbin  tmp

ctrl + d exit release resources, mirror package

root@94a7b7a6ffc0:/# exit
[root@server1 ~]# docker commit -m "add files" vm1 ubuntu:v1
sha256:387e3d445215ca2e177b4c8f0ae3807edffd919a13be237ebcc5e69c4f1523b8

We then use our resealable container mirroring operation.

[root@server1 ~]# docker run -it --name vm2 ubuntu:v1 
root@a5fe8bd9c26b:/# ls
bin   etc     file2  file5  file8  lib    mnt   root  srv  usr
boot  file1   file3  file6  file9  lib64  opt   run   sys  var
dev   file10  file4  file7  home   media  proc  sbin  tmp

We can find our previous documents still being preserved

Two, Dockerfile preparation, the package mirror

Environmental clean-up before the experiment before

  docker rm -f vm1
  docker rm -f vm2
  docker ps -a
  docker rmi ubuntu:v1 

• Write Dockerfile realization install httpd

1. The introduction of the mirror rhel7

[root@server1 ~]# docker load -i rhel7.tar 
e1f5733f050b: Loading layer  147.1MB/147.1MB

2. Write Dockerfile

[root@server1 ~]# docker load -i rhel7.tar 
e1f5733f050b: Loading layer  147.1MB/147.1MB
[root@server1 ~]# cd /tmp/docker/
[root@server1 docker]# vim Dockerfile
[root@server1 docker]# cat Dockerfile 
FROM rhel7		#源镜像是rhel7，最好将rhel7的镜像放在本地
COPY yum.repo /etc/yum.repos.d/yum.repo		##复制一个yum源
RUN rpmdb --rebuilddb && yum install -y httpd	##执行命令安装httpd并清除yum缓存
##rpmdb命令用于初始化和重建rpm数据库 --rebuilddb 从已安装的包头文件，反向重建RPM数据库
EXPOSE 80		##定义端口
CMD ["/usr/sbin/httpd","-D","FOREGROUND"] #打开apache服务-D是全局文件/etc/sysconfig/httpd中打开的参数

3. Write yum.repo (the current directory)

[root@server1 docker]# vim yum.repo
[root@server1 docker]# ca yum.repo
-bash: ca: command not found
[root@server1 docker]# cat yum.repo
[rhel7.3]
name=rhel7.3
baseurl=http://172.25.66.250/rhel7.3
gpgcheck=0

4. The mirror package, and test whether the use of

[root@server1 docker]# docker build -t rhel7:v1 .
注意后面的点，表示当前目录，我们设置其标签为v1

Finally, we can find to write successful

[root@server1 docker]# docker images rhel7:v1 
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
rhel7               v1                  41e959659080        2 minutes ago       193MB

5. We use the new image to run a new container, and the default publishing httpd directory where the file to the default httpd mount the directory publishing

[root@server1 ~]# cd /tmp/docker/
[root@server1 docker]# ls
Dockerfile  index.html  yum.repo
[root@server1 docker]# mkdir web
[root@server1 docker]# mv index.html web/
[root@server1 docker]# docker run -d --name vm1 -p 80:80 -v /tmp/docker/web/:/var/www/html rhel7:v1 
3f1d0e90e349c373c879f361476e81ed2922637035de56962041053bb423d80d
[root@server1 docker]# curl 172.25.66.1
hello
hello
hello

6. We modify the default publishing files, and then continue to access the test

	[root@server1 docker]# cd web/
[root@server1 web]# echo www.ljz.org > index.html 
[root@server1 web]# curl 172.25.66.1
www.ljz.org

We can see if we can modify the default publishing interface

Three, Dockerfile write frequently used instructions

• ADD
  usage and COPY is similar, except that the src can be compressed archive file, the file will be automatically extracted to dest, can also automatically download and copy the URL to the mirror:
  ADD html.tar / var / the WWW
  ADD HTTP: // ip / HTML .tar / var / WWW
• ENV
  setting environment variables, which can be a subsequent instruction uses:
  ENV HOSTNAME sevrer1.example.com
• EXPOSE
  If you run an application service container can be exposed to the service port:
  EXPOSE 80
• VOLUME
  stated data volume, the data is usually specified in the application hanging point:
  VOLUME [ "/ var / WWW / HTML"]
• WORKDIR
  RUN, CMD, EntryPoint, and the ADD COPY command set is mirrored in the current work
  for the directory, if the directory does not exist will be created automatically.
• RUN
  Run command in the container and create a new image layer, commonly used in the installation package:
  RUN yum install -y vim
• CMD differs ENTRYPOINT:
  These two instructions are executed by a command for setting the container after the start, but the CMD is the command line docker run behind the cover, and will not be ignored EntryPoint, will be performed
• Docker run behind the arguments can be passed as an argument to the command ENTRYPOINT.
• Dockerfile can only specify a ENTRYPOINT, if you specify a number, only the last one is valid.

Examples

1. First we import a character image output

[root@server1 ~]# ls
busybox.tar  docker  game2048.tar  nginx.tar  rhel7.tar  ubuntu.tar
[root@server1 ~]# docker load -i busybox.tar 
8a788232037e: Loading layer   1.37MB/1.37MB
Loaded image: busybox:latest

2. Write Dockerfile file

[root@server1 docker]# ls
Dockerfile  web  yum.repo
[root@server1 docker]# vim Dockerfile 
[root@server1 docker]# cat Dockerfile 
FROM busybox
ENV name world	#设置环境变量
ENTRYPOINT echo "hello,$name"

3. create mirror container operation

[root@server1 docker]# docker run --rm busybox:v1  #运行容器后删除
hello,world

4. Here it is necessary to explain a problem, we just used when output is the echo, he is actually a shell format, of course, we can also use the output format exec, will call the bottom shell format / bin / sh -c to execute the command, you can resolve the variable, and can not resolve the variables exec

[root@server1 docker]# vim Dockerfile 
[root@server1 docker]# cat Dockerfile 
FROM busybox
ENV name world
ENTRYPOINT ["/bin/echo","hello,$name"]

So if we must use exec format it, so can we

[root@server1 docker]# vim Dockerfile 
[root@server1 docker]# cat Dockerfile 
FROM busybox
ENV name world
ENTRYPOINT ["/bin/sh","-c","echo hello,$name"]

5. Use ENTRYPOINT and CMD

[root@server1 docker]# vim Dockerfile 
[root@server1 docker]# cat Dockerfile 
FROM busybox
ENTRYPOINT ["/bin/echo","hello"]
CMD ["world"]

Of course, we cmd content can also be covered