How docker replaces a virtual machine

With the popularity of cloud computing and containerization, Docker has quickly become a popular technology in the fields of cloud computing and virtualization. Docker was originally developed as a lightweight container technology, but it has gradually evolved into an alternative to virtual machines. This article will introduce the difference between Docker and traditional virtual machines, and in what scenarios Docker can replace virtual machines.

Virtual machine technology

Before introducing how Docker replaces a virtual machine, we need to first understand what virtual machine technology is.

Virtual Machine (VM) technology is a technology that divides a physical machine into multiple virtual machines. Each virtual machine has a complete operating system and corresponding applications. Virtual machine technology can enable multiple different operating systems to run on the same host, thereby improving resource utilization and system flexibility. However, virtual machines also have some shortcomings, such as large resource usage, slow startup speed, and high deployment costs.

Docker technology

Docker technology is a lightweight container technology that can run multiple independent application containers on an operating system, each container has independent files system and system resources, but they share the same operating system kernel, so they have the characteristics of fast startup speed, low resource usage, and low deployment cost.

Docker containers can be created through Docker images. Docker images are a read-only file system that contains all the components required to run applications, such as applications, library files, operating systems, and systems. Tools etc. Docker containers can be started and stopped in seconds, allowing for rapid deployment and teardown.

The difference between Docker and virtual machines

Compared with virtual machines, Docker has the following differences.

1. Resource consumption

In virtual machines, each virtual machine requires an independent operating system and applications, so each virtual machine needs to consume certain resources. and space. In Docker, all containers share the same operating system kernel and system libraries, so they can utilize the host system's resources more efficiently. Docker's resource usage is only about 1/10 of that of a virtual machine.

2. Deployment speed

The virtual machine needs to copy a complete operating system and application image to the physical host, configure and start it, so its deployment speed slower. The Docker container only needs to package the components required to run the container into an image, and then create the container through the image, so its deployment speed is very fast.

3. Overhead

If you need to run multiple virtual machines, each virtual machine needs to be allocated independent computing resources and storage resources, so the virtual machine overhead is relatively large . In Docker, all containers run on the same operating system and kernel, so they can more efficiently utilize the resources of the host system with less overhead.

4. Migration and expansion

Virtual machines require a series of work such as disk image copying and network configuration to complete migration and expansion. In Docker, containers can be quickly migrated and expanded by creating and distributing images.

Can Docker completely replace virtual machines

Although Docker has many advantages, Docker cannot completely replace virtual machines because their application scenarios and usage methods are still somewhat different.

1. Hardware isolation

Virtual machines can achieve hardware isolation. Each virtual machine can simulate an independent physical computer, so that it can run different operating systems and applications. program. Docker containers share the same operating system kernel, so hardware isolation cannot be achieved.

2. Security

Applications in virtual machines are isolated from each other, so even if an application in a virtual machine is attacked, it will not affect the security of other virtual machines. . In Docker, all containers share the same operating system kernel, so the isolation between containers is relatively weak, and security needs to be enhanced.

Summary

Docker technology can be used as a lightweight container technology, suitable for some scenarios that require rapid deployment, rapid migration and low resource consumption. However, Docker cannot completely replace virtual machines, because virtual machines can achieve hardware isolation and strong security. In actual applications, the combination of virtualization technology and containerization technology needs to be selected based on specific scenarios and requirements.

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