What is docker?

Docker is an open source application container engine that allows developers to package their applications and dependency packages into a portable image and then publish it to any popular Linux or Windows machine. It can also be virtualized ization, and the containers completely use the sandbox mechanism and will not have any interfaces with each other.

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 Virtualization is also possible on popular Linux or Windows machines. Containers completely use the sandbox mechanism and will not have any interfaces with each other.

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will explain to you what Docker is through four points.

• #Docker is the world’s leading software container platform.

• Docker uses the Go language launched by Google for development and implementation. Based on the Linux kernel's cgroup, namespace, and AUFS-like UnionFS and other technologies, it encapsulates and isolates the process and belongs to the operating system level. virtualization technology. Because the isolated process is independent of the host and other isolated processes, it is also called a container. The original implementation of Docke was based on LXC.

• Docker automates repetitive tasks, such as setting up and configuring development environments, freeing developers to focus on what really matters: building Outstanding software.

• Users can easily create and use containers and put their own applications into containers. Containers can also be used for version management, copying, sharing, and modification, just like managing ordinary code.

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The three core concepts of Docker technology are:

• Mirror Image

• ContainerContainer

• Warehouse Repository

The reason why Docker is lightweight What is it? Why does Docker start quickly? How to share the kernel with the host?

When we request Docker to run a container, Docker will set up a resource isolation environment on the computer.

Then copy the packaged application and associated files to the file system within the Namespace. At this time, the configuration of the environment is completed. Docker will then execute the command we specified in advance to run the application.

The image does not contain any dynamic data, and its content will not be changed after it is built.

The core concepts are as follows:

• Build, Ship and Run (build, transport, run).

• Build once, Run anywhere.

• Docker itself is not a container, it is a tool for creating containers and an application container engine.

• Docker’s three core concepts are: Image, Container, and Repository.

• Docker technology uses the Linux kernel and kernel features such as Cgroups and namespaces to separate processes so that they can run independently of each other.

• Since the Namespace and Cgroups features are only available on Linux, containers cannot run on other operating systems. So how does Docker run on macOS or Windows? Docker actually uses a trick and installs a Linux virtual machine on a non-Linux operating system and then runs the container inside the virtual machine.

• An image is an executable package that contains the code, runtime, libraries, environment variables, and configuration files required to run an application. The container is the runtime instance of the image.

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