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Docker is an open source container engine that helps deliver applications faster. Convenience and rapidity is already the biggest advantage of Docker. In the past, tasks that took days or even weeks could be completed in seconds under the Docker container.

Architecture

Docker daemon (Docker daemon): Docker daemon is a background process running on a host (DOCKER-HOST). You can communicate with it through the Docker client. Client (Docker client): the Docker client is the user interface of Docker, which can accept user commands and configuration identities, and communicate with Docker daemon. In the figure, docker build and so on are related commands of Docker. Images (Docker image): the Docker image is a read-only template that contains instructions for creating a Docker container. It is similar to the system installation CD, where you can install the system using the system installation CD. Similarly, you can use the Docker image to run the programs in the Docker image. Container (container): a container is a runnable instance of an image. The relationship between mirrors and containers is somewhat similar to that between classes and objects in object-oriented. You can use Docker API or CLI commands to start, stop, move, and delete containers. Registry:Docker Registry is a service that centrally stores and distributes images. After the Docker image is built, it can be run on the current host. But if you want to run this image on another machine, you need to copy it manually. At this point, you can use Docker Registry to avoid manual replication of the mirror. A Docker Registry can contain multiple Docker repositories, and each repository can contain multiple image tags, each corresponding to an Docker image. This is similar to the Maven repository. If Docker Registry is compared to the Maven repository, then the Docker repository can be understood as the path of a jar package, while the mirror tag can be understood as the version number of the jar package. Docker Registry can be divided into public Docker Registry and private Docker Registry. The most commonly used DockerRegistry is Docker Hub on the official website, which is also the default DockerRegistry. There are a large number of excellent images stored on Docker Hub, which we can download and use using the Docker command.

Installation

Follow the rookie's steps and install it using yum.

Common command

Mirror correlation

Docker search java: search for images with keywords (such as java) in the Docker Hub (or Ali image) repository docker pull java:8: download images from the repository. To specify a version, specify docker images after the colon: list the downloaded images docker rmi java: delete the local image docker build: build the image

Container dependence

Docker run-d-p 91:80 nginx: run nginx in the background. If there is no image, download it first, and map port 80 of the container to port 91 of the host. -d: background operation-P: random port mapping-p: specify port mapping-net: network mode docker ps: list running containers docker ps-a: list all containers docker stop container id: stop container docker kill container id: force stop container docker start container id: start stopped container docker inspect container id: view all information of container docker container logs container id: check container log docker Top container id: view processes in container docker exec-it container id / bin/bash: enter container exit: exit container docker rm container id: delete stopped container docker rm-f container id: delete running container

All commands

Docker

Docker COMMAND-help

Build an image

Determine the image template, such as java, nginx

Create a new Dockerfile file

Use the instructions of Dockerfile to improve the content of Dockerfile

Execute docker build-t imageName:tag.,-t to specify the image name in the path of the Dockerfile file, and execute docker run-d-p 92:80 imageName:tag to identify the path of the Dockerfile file at the end.

Note: the RUN command is executed during the construction phase of the image file, and the execution results are packaged into the image file; the CMD command is executed after the container starts. In addition, a Dockerfile can contain multiple RUN commands, but only one CMD command. Note that once the CMD command is specified, the docker container run command cannot attach a command, otherwise it will override the CMD command.

Docker Compose

Docker Compose is a command-line tool provided by docker to define and run applications composed of multiple containers. With compose, we can define each service of the application declaratively through the YAML file, and the application is created and started by a single command.

These are all the relevant knowledge points of this introduction. If you have anything to add, you can contact the editor.

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