Docker has two meanings: 1. Refers to the English word docker, whose Chinese translation is "docker"; 2. Refers to the Docker container, which is an open source application container engine that allows developers to package their applications And dependency packages into a portable image, and then published to any popular operating system machine, virtualization can also be achieved.
The operating environment of this article: ubuntu 18.04 system, Docker version 20.10.11, Dell G3 computer.
What does docker mean?
docker has two meanings:
1. The Chinese translation of the English word docker is dock worker (noun), and the third person plural is dockers;
2. Refers to Docker
Container
Docker is an open source application container engine that allows developers to package their applications and dependencies into a portable image and then publish it to any popular Linux Or virtualization can also be implemented on machines with Windows operating systems. Containers completely use the sandbox mechanism and will not have any interfaces with each other.
Docker containers are similar to virtual machines, but they are different in principle. Containers virtualize the operating system layer, and virtual machines are virtualized hardware. Therefore, containers are more portable and use servers efficiently. Containers are used more to represent a standardized unit of software. Due to the standardization of containers, it can be deployed anywhere regardless of infrastructure differences. In addition, Docker also provides containers with stronger industry isolation compatibility.
Docker uses the resource separation mechanism in the Linux core, such as cgroups, and Linux core namespaces (namespaces), to create independent containers (containers). This can operate under a single Linux entity, avoiding the additional burden of launching a virtual machine [3]. The Linux kernel's support for namespaces completely isolates the application's view of the working environment, including the process tree, network, user ID and mounted file system, while the core cgroup provides resource isolation, including CPU, memory, block I/O and network. Starting from version 0.9, Dockers began to include the libcontainer library as a direct use of the virtualization facilities provided by the Linux kernel in its own way, based on the interface provided by libvirt's LXC and systemd-nspawn,
According to industry analyst firm “451 Research”: “Dockers are dependency tools that have the ability to package applications and their virtual containers that can be executed on any Linux server, which helps achieve flexibility and portability of applications. The program can be executed anywhere, whether it is a public cloud server, a private cloud server, a stand-alone machine, etc."
A complete Docker consists of the following parts:
DockerClient
Docker Daemon
Docker Image
DockerContainer container
Recommended learning: "Docker Video Tutorial"
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