Docker, what is it?

Source: Internet
Author: User

New technology more and more, recently constantly by the friends around the brain, as if not to write a new technology, there is no face in the IT circle mixed. Well, let me also embrace the open source technology and write about Docker. What the hell is Docker?

This is said in the Docker manual:

Docker is an open-source engine that makes it easy to create a lightweight, portable, self-sufficient container for any application. Developers who compile tests on notebooks can be deployed in batches in a production environment, including VMS (virtual machines), bare metal, OpenStack clusters, and other underlying application platforms.

Docker and "container"

We often say that Docker helps us realize the function of "container".

the real world container That is , it solves the problem of the transport of goods, "container" can help us to solve various types of specifications of the size of the goods in a variety of transport tools to facilitate transport.

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so Docker in it technology What does it do? originally it was to help us solve the "shipping" problem of software . It can package a variety of applications and the running environment they rely on as standard container/image, and then publish to different platforms to run.

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So, in a way, Docker can be seen as an international container written in code. Docker can package any application and related dependencies into a lightweight, portable, self-inclusion container that has standard operations that enable automation.

from the features of the container, look at Docker

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Content Independence

The same container can hold almost any type of cargo, and Docker can encapsulate code, environment, configuration files, loads, and dependencies.

Hardware agnostic

Containers are allowed to transport goods from ships to trains and trucks until they are transported to warehouses, without having to tidy up the goods or open the containers. Docker uses operating system primitives (for example: LXC) to run on virtually any platform-virtual machines, bare metal, OpenStack, public IaaS, and so on-without modification.

Isolation and interaction of content

Containers do not have to worry about the goods in various boxes, they will not affect each other, we can accumulate transport. Docker isolates resources, networks, and content to avoid dependencies.


Container standard specifications make it easy to achieve automatic loading and unloading, transportation, etc., Docker to run, start, stop, submit, search, etc. have standard operation.

Efficient, fast

The container does not have to be opened or modified, can be moved/transported quickly in both places, Docker is lightweight, one build can be run anywhere, allowing us to quickly move and operate.

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The question is: What is the difference between Docker and virtualization?

Tell the story and explain it to you.

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In ancient times, a king inspected the country's borders, because the road was bumpy, and there were many gravel heads, and the feet of the king were sore and numb.

Back to the palace, he made an order to the domestic all roads are paved with a layer of cowhide. Let himself and the people of the country walk no longer suffering from the sting. The ministers listened to the king's words and helpless, knowing it was difficult. Even if all the domestic cattle are killed, there is not enough cowhide to pave the road, and expensive. Then a wise servant made a statement to the king: he could try to wrap his feet in cowhide, and the king's feet would not endure pain. The king heard the word and epiphany, then took back the order, adopted the advice, so the shoes were invented.

Extended to Docker and virtualization

OK, everyone must ask me, Han Meimei children's shoes What do you want to explain? A review of the story, to solve the foot pain inconvenient solution has two: The 1th option is: All roads are covered with a layer of cowhide (such as VMware), it is not affordable. The 2nd option is to cover the feet with two pieces of cowhide, which is the leather shoes (Docker container). So, what do you realize? At least it is clear that the 2nd scheme can bring considerable economic benefits.

Traditional virtualization (Virtualization) technology is equivalent to a layer of cowhide (VM, virtual Machine) on each road (physical machine), and then let the King's Foot (APP) walk (execute) on the cowhide (VM). Traditionally, the cloud platform has taken the virtualization approach to meet the individual resource allocation requirements and ensure its availability and isolation. However, the guest OS, such as KVM and Xen, are wasteful and difficult to manage, and are less flexible, faster, and more resource-efficient than Docker containers (leather shoes).

All right, let's take a look at the comparison chart.

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The question comes again: Will Docker take the place of virtualization

At this stage, the traditional virtual technology will not be replaced. Docker or container technology and virtual machines are not simply a matter of trade-offs. Today, many businesses are still using virtual machine technology for the simple reason that they need an efficient, secure, and highly available architecture. However, the new two-year-old Docker has not been tested, and the concept of CaaS (Container as a service, container-as-a-serve) has only just emerged in the last two years. Docker is still at the stage of development and refinement, whether it is application management or operational maintenance.


As the saying goes: The world Military study, only fast not broken, in the update iteration so fast it is more so, overnight fame is not a news. Docker, the technology company, proves to us that it takes only one months to become an "international superstar". Open source was decided in February 2013, and it took only one months to release Docker0.1 by March 20, 2013. Today, a small start-up ecosystem around Docker is evolving. Docker has won the favor of Google, Microsoft, Amazon, VMware and other giants, the Giants have signalled to ensure that their platform and Docker container technology compatibility, Docker unstoppable.

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Docker, what is it?

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