Students who have had background development experience must have encountered these problems:
The program runs well in the development environment, but deploys to the production environment, but the situation is frequent;
Suppose a program is to be deployed in the customer's environment. Although it is deployed and verified successfully in its own environment, it is always worried that the customer's environment lacks some necessary library files, or the versions of some files do not meet the requirements.
Well, with docker, these problems will no longer exist.
Docker is a virtual environment container that can package your executable files, configuration files, and all other files you need into this container, and publish and apply it to any platform. For example, you have developed a website behind the scenes in Python. After the development test is completed, you can package Python3 and its dependencies, Flask and its various plugins, MySQL, Nginx, etc. into a container and deploy it to whatever you want. Deployed to the environment.
If you don't understand it, let's use the container to make an analogy.
What problem does the container solve? In a large ship, the goods can be put in order. And all kinds of goods are standardized by containers, and containers and containers do not affect each other. Then I don't need a special ship that transports fruit and a ship that specializes in transporting chemicals. As long as these goods are packaged well in the container, I can use a large ship to carry them all away.
Docker is a similar idea. We can run multiple docker containers that are not related to each other on a single machine. Each container is equivalent to a container.
Several basic concepts in Docker
Image
Mirroring can be understood as a pile of static files
container
The container is an instance after the image has been run. Mirroring in containers is like object-oriented programming in the class object.
warehouse
The mirror needs to be saved somewhere. This place is the warehouse
Differences from traditional virtualization
Here we talk about traditional virtualization.
We can see that traditional virtualization is based on hardware physical resources, virtualizing multiple OSs, and building a relatively independent program execution environment on the basis of OS. Dokcer is virtual on the basis of OS. Obviously, Dokcer is much lighter, so its resource consumption and performance consumption have advantages over traditional virtualization.
After working in the IT industry for many years, we are also looking at the era from the physical server to the virtualized cloud computing era. We are ready to enter the Docker era. As the next generation of virtualization technology, Docker is changing the way the industry develops, tests, and deploys applications. As for the difference between virtualization technology and docker technology, the following analysis.
01 What is virtualization?As the name suggests, virtualization technology is a virtual pool of physical resources into a form of technology, there is a virtual reality and more virtual one and two forms, such as personal computers installed VMware software, you can install other Win systems, MacOS , Linux systems, etc., to achieve the advantages of a computer / notebook carrying multiple systems, the current dual-system solutions for Apple laptop users are also based on virtual machines, ordinary Windows users may not be in great demand, and technical personnel are basic software Now.
At the enterprise level, multiple virtual ones are the main form, that is, a large number of physical server clusters are virtualized to form a resource pool, and various virtual machines are created on this resource for flexible deployment.
02 What is DockerIn fact, docker and virtual technology are similar, but there are some differences, on the one hand, on the level of two technologies, the virtual machine is generally supported by the underlying hardware Hardware, the upper layer is the hypervisor layer of the virtual management system, and different VM services are enabled on the upper layer. If you need to isolate these services, you need each VM to start the guest operating system, which is very resource consuming.
Docker is completely different, the underlying hardware and Host OS system support, such as Windows/MacOS/Linux, throw away the bloated system, but instead of the Docker daemon, the upper layer to create different containers, different application images packaged in different In the container, they are isolated from each other.
03 The difference between virtualization and dockerThe docker is small in design, fast in deployment and migration, efficient in operation, independent of applications, and managers can see the content of all containers. The virtualization technology is bloated. No matter what the application needs, a new system needs to be created first, and it is not based on application isolation. But according to the system isolation, the administrator cannot see the internal information of the system.
For example, Docker is just a variety of APPs in your mobile phone. You only need one system to download the applications you need. However, virtualization technology is equivalent to installing a huge amount of software on your iPhone. This software installs Android and Meizu system. And so on, each type of application must be installed on each system, which is troublesome.
But the two are not absolutely good or bad, mainly to see the application scenario, according to different needs to choose different solutions.
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