Docker is an open source application container engine that makes it easy to create a lightweight, portable, self-sufficient container for any application. Using Linux's LXC, AUFS, Go language, and cgroup to achieve resource independence, you can easily isolate files, resources, and networks. The ultimate goal is to achieve application isolation similar to PaaS platforms.
Notable features of Docker:
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File system isolation: Each process container runs in a completely independent root file system.
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Resource isolation: System resources, such as CPU and memory, can be allocated to different containers using cgroups.
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Network isolation: Each process container runs in its own network space, virtual interface and IP address.
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Logging: Docker will collect and log standard streams (stdout/stderr/stdin) per process container for real-time retrieval or batch retrieval.
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Change Management: Changes to a container's filesystem can be committed to a new image and reused to create more containers. No templates or manual configuration required.
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Interactive shell: Docker can allocate a virtual terminal and attach it to the standard input of any container, for example to run a one-time interactive shell.
Docker is usually used in the following scenarios:
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Automated packaging and publishing of web applications;
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Automated testing and continuous integration, release;
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Deploy and tune databases or other background applications in a service-based environment;
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Build your own PaaS environment by compiling or extending an existing OpenShift or Cloud Foundry platform from scratch.
This article describes how to install Docker in a RedHat/CentOS environment. Official documents require that the Linux kernel be at least 3.8 or above, and docker can only run on 64-bit systems. Since the kernel version of RHEL6 and CentOS6 is 2.6, the kernel must be upgraded first.
The following takes CentOS6.5 (64-bit) as an example to introduce the docker installation steps and usage:
1. Upgrade the kernel (with aufs module, remember to upgrade, otherwise there will be many inexplicable problems, it is recommended to use yum to install)
1. yum install the 3.10 kernel with the aufs module (or download the kernel here for manual installation: http://down.51cto.com/data/1903250 )
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1
2
3
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cd
/etc/yum
.repos.d
wget http:
//www
.hop5.
in
/yum/el6/hop5
.repo
yum
install
kernel-ml-aufs kernel-ml-aufs-devel
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2. Modify grub's main configuration file /etc/grub.conf and set default=0, which means that the content under the first title is the kernel that is started by default (generally the newly installed kernel is in the first position).
3. Restart the system. At this time, your kernel has been successfully upgraded.
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2
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[root@localhost ~]
# uname -r
3.10.5-3.el6.x86_64
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Check if the kernel supports aufs:
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2
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[root@localhost ~]
# grep aufs /proc/filesystems
nodev aufs
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2. Install docker
1、首先关闭selinux：
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1
2
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setenforce 0
sed
-i
'/^SELINUX=/c\SELINUX=disabled'
/etc/selinux/config
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2. The docker-io package has been provided in the Fedora EPEL source, download and install epel:
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1
2
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rpm -ivh http:
//mirrors
.sohu.com
/fedora-epel/6/x86_64/epel-release-6-8
.noarch.rpm
sed
-i
's/^mirrorlist=https/mirrorlist=http/'
/etc/yum
.repos.d
/epel
.repo
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3. yum install docker-io:
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1
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yum -y
install
docker-io
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4. Start docker:
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1
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service docker start
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5. Check the docker version:
View docker logs:
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1
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cat
/var/log/docker
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Third, the use of docker commands
1. Enter the docker command directly to view all Options and Commands.
View the detailed usage of a command: docker COMMAND --help
2. Search for available docker images: docker search NAME
3. Download the image: docker pull NAME[:TAG]
For example, to get the latest centos image: docker pull centos:latest
Note: Write the full image name searched by docker search here.
4. View the installed image: docker images [NAME]
5. Run the command in the docker container: docker run IMAGE [COMMAND] [ARG...]
The docker run command has two parameters, one is the image name and the other is the command to run in the image.
Note: IMAGE=REPOSITORY[:TAG], if the IMAGE parameter does not specify the TAG of the image, the default TAG is latest.
Output "hello word" in the image you just downloaded: docker run centos echo 'hello world!'
6. List containers: docker ps -a
View recently generated containers: docker ps -l
View running containers: docker ps
7. Display the standard output of the container: docker logs CONTAINERID
There is no need to copy the complete id, generally write the first three to four characters.
8. Install new programs in the container, such as installing the ifconfig command (centos7 does not have ifconfig by default): docker run centos yum install net-tools -y
If yum does not specify the -y parameter, the yum command will enter the interactive mode, requiring the user to enter a command for confirmation, which cannot be responded to in the docker environment. But using the -i -t parameters of docker run will respond to this interaction, and the user can enter commands, such as: docker run -i -t centos yum install net-tools
9. Save the changes to the container and generate a new image: docker commit CONTAINERID [REPOSITORY[:TAG]]
The REPOSITORY parameter can be the new image name or the old image name; if the name and TAG of the old image are the same, the old image will be overwritten.
10. Stop the running container: docker stop CONTAINER ID
By default wait 10 seconds before killing the specified container. The wait time can be set with the -t parameter.
11. View the details of the container or image: docker inspect CONTAINER ID |IMAGE
The parameter can be the container ID or the image name (NAME:TAG).
12. Delete the container: docker rm CONTAINERID
View all container IDs: docker ps -a -q
Remove all containers: docker rm $(docker ps -a -q)
13. Delete the image: docker rmi IMAGE
14. View docker information, including the number of Containers and Images, kernel version, etc.
Fourth, the operation of creating a container and logging in
1. Create a new container and log in: docker run -i -t IMAGE /bin/bash
Use the image to create a container and enter the interactive mode, the login shell is /bin/bash, and now you can freely operate the container. Finally use exit to exit the container.
Note: If the IMAGE parameter does not specify TAG, the default TAG is latest.
2. Start an exited container: docker start CONTAINERID
3. Attach to the running container: docker attach CONTAINERID
Reprint address: http://blog.csdn.net/wuzhilon88/article/details/41621285/