Examples of using Docker and Docker-Compose

Docker is an open source container engine that helps deliver applications faster. Convenience and speed are already the biggest advantages of Docker. Tasks that used to take days or even weeks can now be completed in seconds using Docker containers.

Architecture

• Docker daemon: Docker daemon is a background process running on the host (DOCKER-HOST). It can be communicated with through the Docker client.
• Client (Docker client): The Docker client is the user interface of Docker, which can accept user commands and configuration identifiers and communicate with the Docker daemon. In the figure, docker build and others are all Docker related commands.
• Images: A Docker image is a read-only template that contains instructions for creating a Docker container. It is a bit like a system installation CD. You can use the system installation CD to install the system. Similarly, you can use the Docker image to run the program in the Docker image.
• Container: A container is a runnable instance of an image. The relationship between images and containers is somewhat similar to the relationship between classes and objects in object-oriented programming. Containers can be started, stopped, moved, and deleted through Docker API or CLI commands.
• Registry: Docker Registry is a service for centralized storage and distribution of images. After building the Docker image, you can run it on the current host. But if you want to run this image on other machines, you need to copy it manually. At this time, you can use Docker Registry to avoid manual copying of images. A Docker Registry can contain multiple Docker repositories, each repository can contain multiple image tags, and each tag corresponds to a Docker image. This is somewhat similar to Maven's warehouse. If Docker Registry is compared to Maven's warehouse, then the Docker warehouse can be understood as the path of a jar package, and the image 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 Docker Registry is the official Docker Hub, which is also the default Docker Registry. There are a lot of excellent images stored on Docker Hub, which we can download and use using Docker commands.

Install

Follow the novice steps and use yum to install it.

Common commands

Mirror related

• docker search java: Search for images with keywords (such as java) in the Docker Hub (or Alibaba Mirror) repository
• docker pull java:8: Download the image from the repository. If you want to specify the version, specify it after the colon.
• docker images: list downloaded images
• docker rmi java: delete local image
• Docker build: Build an image
  

Container related

• 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: Run in the background
• -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 the container
• docker kill container id: force stop container
• docker start container id: start a stopped container
• docker inspect container id: view all information of the container
• docker container logs container id: view container logs
• docker top container id: view the process in the container
• docker exec -it container id /bin/bash: enter the container
• exit: exit the container
• docker rm container id: delete the stopped container
• docker rm -f container id: delete the running container
  

All commands

• docker
  
• docker COMMAND --help
  

Build the image

• Determine the image template: such as java, nginx
  
• Create a new Dockerfile
  
• Use the Dockerfile instructions to complete the Dockerfile content
  
• Execute docker build -t imageName:tag . in the path where the Dockerfile file is located. -t specifies the image name, and the dot at the end indicates the path of the Dockerfile file.
• Execute docker run -d -p 92:80 imageName:tag

Note: The RUN command is executed during the image file building phase, and the execution results are packaged into the image file; the CMD command is executed after the container is started. In addition, a Dockerfile can contain multiple RUN commands, but only one CMD command. Note that after specifying the CMD command, the docker container run command cannot be appended with a command, otherwise it will overwrite the CMD command.

Docker Compose

Docker Compose is a command line tool provided by Docker for defining and running applications consisting of multiple containers. Using compose, we can declaratively define the services of an application through a YAML file and create and start the application with a single command.

The above are all the relevant knowledge points introduced this time. If you have any supplements, please contact the editor of 123WORDPRESS.COM.