In docker, a container is a runtime instance of an image, similar to a lightweight sandbox, which can be started, started, stopped, and deleted. Docker uses containers to run and isolate applications; each container is an isolated and secure platform.
The operating environment of this tutorial: linux5.9.8 system, docker-1.13.1 version, Dell G3 computer.
Docker includes three basic concepts
Image
Container
Repository
##Docker image
Docker image (Image) is similar to the image of a virtual machine, which can be It is understood as a read-only template for the Docker engine, including the file system. For example: an image can completely contain the Ubuntu operating system environment, and it can be called an Ubuntu image. The image can also have an Apache application (or other software) installed, which can be called an Apache image. Images are the basis for creating Docker containers. Through version management and incremental file systems, Docker provides a very simple mechanism to create and update existing images. Users can download a prepared application image from the Internet and use it directly through commands. In short, an application requires an environment to run, and mirroring is here to provide this environment.Docker container
Docker container (Container) is similar to a lightweight sandbox (because Docker is a virtual technology based on the Linux kernel, it consumes very few resources ), Docker uses containers to run and isolate applications. A container is a runtime instance of an image. It can be started, started, stopped, deleted. Each container is an isolated and secure platform. Schematic diagram of using a single Docker image to start multiple containers
Docker warehouse
Docker warehouse (Repository) is similar to a code warehouse and is a place where Docker stores image files centrally. Each warehouse can contain multiple tags, and each tag corresponds to an image. Usually, a warehouse will contain images of different versions of the same software, and tags are often used to correspond to each version of the software. Recommended learning: "docker video tutorial"
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Installing and configuring Docker on Linux requires ensuring that the system is 64-bit and kernel version 3.10 and above, use the command "sudoapt-getupdate" and install it with the command "sudoapt-getupdate" and verify it with "sudoapt-getupdate" and. Docker uses the namespace and control groups of the Linux kernel to achieve container isolation and resource limitation. The image is a read-only template, and the container can be modified. Examples of usage include running an Nginx server and creating images with custom Dockerfiles. common

The reason for using Docker is that it provides an efficient, portable and consistent environment to package, distribute, and run applications. 1) Docker is a containerized platform that allows developers to package applications and their dependencies into lightweight, portable containers. 2) It is based on Linux container technology and joint file system to ensure fast startup and efficient operation. 3) Docker supports multi-stage construction, optimizes image size and deployment speed. 4) Using Docker can simplify development and deployment processes, improve efficiency and ensure consistency across environments.

Docker's application scenarios in actual projects include simplifying deployment, managing multi-container applications and performance optimization. 1.Docker simplifies application deployment, such as using Dockerfile to deploy Node.js applications. 2. DockerCompose manages multi-container applications, such as web and database services in microservice architecture. 3. Performance optimization uses multi-stage construction to reduce the image size and monitor the container status through health checks.

Select Docker in a small project or development environment, and Kubernetes in a large project or production environment. 1.Docker is suitable for rapid iteration and testing, 2. Kubernetes provides powerful container orchestration capabilities, suitable for managing and expanding large applications.

Docker is important on Linux because Linux is its native platform that provides rich tools and community support. 1. Install Docker: Use sudoapt-getupdate and sudoapt-getinstalldocker-cedocker-ce-clicotainerd.io. 2. Create and manage containers: Use dockerrun commands, such as dockerrun-d--namemynginx-p80:80nginx. 3. Write Dockerfile: Optimize the image size and use multi-stage construction. 4. Optimization and debugging: Use dockerlogs and dockerex

Docker is a containerization tool, and Kubernetes is a container orchestration tool. 1. Docker packages applications and their dependencies into containers that can run in any Docker-enabled environment. 2. Kubernetes manages these containers, implementing automated deployment, scaling and management, and making applications run efficiently.

The purpose of Docker is to simplify application deployment and ensure that applications run consistently in different environments through containerization technology. 1) Docker solves the environmental differences problem by packaging applications and dependencies into containers. 2) Create images using Dockerfile to ensure that the application runs consistently anywhere. 3) Docker's working principle is based on images and containers, and uses the namespace and control groups of the Linux kernel to achieve isolation and resource management. 4) The basic usage includes pulling and running images from DockerHub, and the advanced usage involves managing multi-container applications using DockerCompose. 5) Common errors such as image building failure and container failure to start, you can debug through logs and network configuration. 6) Performance optimization construction

The methods of installing and using Docker on Ubuntu, CentOS, and Debian are different. 1) Ubuntu: Use the apt package manager, the command is sudoapt-getupdate&&sudoapt-getinstalldocker.io. 2) CentOS: Use the yum package manager and you need to add the Docker repository. The command is sudoyumininstall-yyum-utils&&sudoyum-config-manager--add-repohttps://download.docker.com/lin


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