Docker introduction and practical explanation

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Briefly

Docker is an open source application container engine that allows developers to package their applications and dependencies into a portable container, which can then be distributed to any popular Linux machine, and can also be virtualized. Containers are completely sandboxed and do not have any interface with each other (similar to iPhone apps). There is almost no performance overhead and can be easily run in machines and data centers. Most importantly, they do not depend on any language, framework including system.

What is Docker?

Docker is a cloud open source project based on the Go language. It was born in early 2013 and was originally initiated by dotCloud.

Docker achieves the "package once, run everywhere" at the application component level by managing the life cycle of application components such as packaging, distribution, deployment, and operation. The application component here can be a Web application, a set of database services, or even an operating system or a compiler.

Docker consists of three cores: Image, Container, and Repository.

Why use Docker?

Faster delivery and deployment (using docker, developers can use images to quickly build a standard development environment; after development is complete, test and operations personnel can directly use the same environment to deploy code.)

Easier migration and scaling (docker containers can run on almost any platform, including physical machines, virtual machines, public clouds, private clouds, PCs, servers, etc. Applications can be easily migrated across different platforms)

Simpler update management (using Dockerfile, you only need to modify a small configuration, you can replace a lot of update work in the past)

Compared with traditional virtual machines

Scenario Example - Traditional Development Process

Scenario example - docker environment development process

Install the docker program under Linux

Environmental preparation

1. Linux7 or above or cent OS6 and above

2. Kernel 3.1.0 or above

3. 64 - bit operating system

install docker

1. yum install yum install docker - engine

2 , curl script installation

Docker command usage → image

Create an image

1. Create a container based on an existing image

docker commit [options] container[repository]

option:-a, --author="" author information

-m,--message="" submit message

-p, --pause=true Pause the container on commit

2. Import and create based on local template

docker load < ***.tar -- local template file tar

3. Build an image based on the Dockerfile file
docker build –t image-name basedir

Docker command usage → delete image

delete mirror

dockerrmi image

dockerrmi –f image –强制删除镜像

其中image可以为标签或者ID

注意：

用dockerrmi删除镜像时，首先删除容器，再删除镜像。

Docker命令用法→容器

创建 |启动容器

docker create image 创建的容器是停止状态

docker start/stopcontainer_id启动/停止容器

docker run image创建并启动容器

备注：image-可以为镜像标签或Id

container_id为容器id

Docker数据卷→介绍

数据卷是一个特别指定的目录，该目录利用容器的UFS文件系统可以为容器提供一些稳定的特性或者数据共享。数据卷可以在多个容器之间共享。

创建数据卷，只要在dockerrun命令后面跟上-v参数即可创建一个数据卷，当然你也可以跟多个-v参数来创建多个数据卷，当创建好带有数据卷的容器后，你就可以在其他容器中通过--volumes-froms参数来挂载该数据卷了，而不管该容器是否运行。你也可以在Dockerfile中通过VOLUME指令来增加一个或者多个数据卷。