Docker is not an operating system; an operating system is a set of interrelated system software programs that supervises and controls computer operations, uses and runs hardware and software resources, and provides public services to organize user interaction, while docker is An open platform for developing, delivering and running applications, Docker also makes it possible to manage infrastructure in the same way as applications.
The operating environment of this tutorial: linux7.3 system, docker version 19.03, Dell G3 computer.
Docker is essentially an add-on system, to be precise, an open platform for developing, delivering and running applications; Docker enables developers to Separate applications from infrastructure so you can deliver software quickly; with Docker you can also manage infrastructure the same way you manage applications.
Docker is not an operating system. Docker is a container. It can be compared to virtual hardware. The operating system is installed on the hardware (host). The redis image must be a system with redis installed, not With a single redis, you can enter the image and use relevant commands to view system information.
What is an operating system?
The operating system (English: Operating System, abbreviation: OS) is a group of computers that supervises and controls the operation, use and running of hardware and software resources. and interrelated system software programs that provide common services to organize user interactions. According to the operating environment, operating systems can be divided into desktop operating systems, mobile operating systems, server operating systems, embedded operating systems, etc.
What is docker
Docker is an open source application container engine that allows developers to package their applications and dependencies into a portable image, and then Publishing to any popular Linux or Windows operating system machine can also be virtualized. Containers completely use the sandbox mechanism and will not have any interfaces with each other.
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Advantages of Docker
Docker is a tool for development, delivery and An open platform for running applications. Docker enables you to separate applications from infrastructure so you can deliver software quickly. With Docker, you can manage your infrastructure the same way you manage your applications. By leveraging Docker's approach to quickly delivering, testing, and deploying code, you can significantly reduce the delay between writing code and running it in production.
Features
The typical scenarios of docker are mentioned on the docker website:
Automating the packaging and deployment of applications (Automate application packaging and deployment)
Creation of lightweight, private PAAS environments (Create lightweight, private PAAS environments)
Automated testing and continuous integration/deployment
Deploying and scaling web apps, databases and backend services )
Due to its lightweight virtualization characteristics based on LXC, the most obvious feature of docker compared to KVM and the like is that it starts quickly and takes up less resources. Therefore, it is necessary to build an isolated and standardized operating environment, lightweight PaaS (such as dokku), build automated testing and continuous integration environments, and all applications that can be horizontally expanded (especially web applications that need to start and stop quickly to cope with peaks and valleys) .
To build a standardized operating environment, most of the existing solutions are to run a set of puppet/chef or an image file on a baseOS. The disadvantage is that the former requires many prerequisites of base OS, and the latter is almost impossible. Modify (because the file format of copy on write is read only when rootfs is running). Moreover, the latter file size is large, and environment management and version control itself are also a problem.
The PaaS environment is self-evident. At the beginning of its design and in the case of dotcloud, it was used as the environmental basis of PaaS products
because of its standardized construction method (buildfile) and good REST API, automated testing and continuous integration/deployment can be well integrated
Because of the lightweight characteristics of LXC, it starts quickly, and docker can only load the changed parts of each container, so that it takes up little resources , it can be faster and occupy less resources than virtualization solutions such as KVM in a stand-alone environment
Recommended learning: "docker video tutorial"
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