What kind of technology is docker?

Docker is a lightweight virtualization technology that allows developers to encapsulate various applications and application dependency files needed by enterprises into Docker image files, and then install and run them on any physical device to achieve virtualization ization, allowing applications to be completely separated from underlying devices, enabling flexible migration and deployment between physical machines, and reducing potential risks during the deployment process.

The operating environment of this tutorial: linux5.9.8 system, docker-1.13.1 version, Dell G3 computer.

Docker is a lightweight virtualization technology and an open source application container running environment building platform that allows developers to conveniently package applications into a portable container and then install it on any server running Linux or Windows, etc. Compared with traditional virtual machines, Docker containers provide lightweight virtualization methods, easy installation, and fast start and stop speeds.

Why do you need Docker containers?

The development of virtual machine (Virtual Machine, referred to as VM) has reduced enterprises' dependence on hardware resources. It virtualizes one physical device into multiple logical devices, and each logical device can run different operating system, and applications can run in independent spaces without affecting each other, thereby significantly improving the work efficiency of the device. However, traditional VMs require the installation of an operating system to execute applications, which consumes too many system resources. In most cases, users only need to run simple applications, and using VM technology is cumbersome and wastes resources. If application service programs need to be migrated, the entire VM needs to be migrated, so enterprises urgently need lightweight virtualization technology.

Containers are a lightweight virtualization technology with the same purpose as virtual machines, which is to create an "isolated environment". But unlike VMs, which use operating system-level resource isolation, containers use process-level system isolation. As a mainstream tool for creating containers, Docker has developed rapidly in recent years. Its advantage is that it allows developers to encapsulate various applications and application dependency files needed by enterprises in Docker image files, and then run them on any physical device (Linux device or Window device). etc.) to implement virtualization, allowing applications to be completely separated from the underlying equipment, and can be flexibly migrated and deployed between physical machines, freeing operation and maintenance engineers from cumbersome environment deployment, greatly improving work efficiency and reducing deployment costs. potential risks in the process.

Docker containers have the following three major characteristics:

• Lightweight: Multiple Docker containers running on a host can share the host operating system Kernel; starts quickly and requires very little computing and memory resources.

• Open standards: Docker containers are based on open standards and can run on all major Linux versions, Microsoft Windows, and any infrastructure including VMs, bare metal servers, and the cloud.

• Safe and reliable: The isolation that Docker gives applications is not limited to isolation from each other, but is also independent of the underlying infrastructure. Docker provides the strongest isolation by default, so if there is an application problem, it is only a problem with a single container and will not affect the entire host.

The advantages of docker mainly include the following aspects:

• Quick delivery and deployment

  Use With docker, developers can use images to quickly build a standard development environment; after development is completed, testing and operation and maintenance personnel can use the exact same environment to deploy code. As long as the code has been developed and tested, it can ensure seamless operation in the production environment. . Docker can quickly create and delete containers to achieve rapid iteration.

• Efficient resource utilization

  Running docker containers does not require the support of additional virtualization management programs. Docker is kernel-level virtualization, which can achieve higher performance , while requiring very little additional resource demand.

• Easy migration and expansion

  Docker containers can run on almost any platform, including physical machines, virtual machines, public clouds, private clouds, servers, etc. It also supports mainstream operating system releases. This compatibility allows users to easily migrate applications between different platforms.

• Simple update management

  Using Dockerfile to generate images, only small configuration modifications are needed to replace a large amount of update work in the past, and all modifications can be Distribute and update incrementally for automated and efficient container management.

The difference between docker and virtual machines

• Docker is a lightweight virtualization method that runs Compared with traditional virtual machines, it has the following significant advantages in application:

• Docker containers are very fast, and can be started and stopped in seconds, compared with traditional virtual machines which take several minutes Much faster

• Docker requires very little system resources, and thousands of Docker containers can be run simultaneously on one host

• Docker passes Operations similar to Git design concepts facilitate users to obtain, distribute and update images, store reuse, and incremental updates

• In addition to running applications, Docker containers basically consume no additional system resources. Their applications obtain near-native performance. Traditional virtual machines require separate allocation of memory, disk and other resources

• Docker supports a flexible automated creation and deployment mechanism through Dockerfile to improve work efficiency and standardize the process

• Docker facilitates migration. You can push the image to the warehouse through Pull the image to start docker on any machine

In short, docker is lighter and more convenient to use than a virtual machine

Recommended study: "docker video tutorial 》

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