How to use Docker to achieve rapid migration and remote management of containers on Linux?

How to use Docker to achieve rapid migration and remote management of containers on Linux?

Overview
Docker is a commonly used containerization technology that enables rapid deployment and management of applications. In the Linux environment, the installation and use of Docker is relatively simple and can be operated through the command line or visual tools. This article will introduce how to use Docker to implement rapid migration and remote management of containers on Linux, and provide corresponding code examples.

1. Docker installation and configuration
   First, you need to install Docker on the Linux system. In most Linux distributions, it can be installed through package managers such as apt, yum or dnf. The following is an example command to install Docker on an Ubuntu system:

   $ sudo apt-get update
   $ sudo apt-get install docker.io

   After the installation is completed, you can verify whether Docker is successfully installed by using the following command:

   $ docker version

   Next, you need to create a remote access Docker user group. You can manually create a group and then add existing users to the group. Then, you need to log in again for the user group changes to take effect:

   $ sudo groupadd docker
   $ sudo usermod -aG docker $USER
   $ newgrp docker

   Finally, you need to restart the Docker service to make it take effect:

   $ sudo systemctl restart docker

2. Quick Migration of Containers
   Docker Containers Rapid migration is the process of moving containers from one host to another. In order to achieve rapid migration of containers, you need to package the container into an image and then rerun the image on the new host.

First, save the current status of the container as an image on the source host:

$ docker commit <container_id> <image_name>

Where, <container_id> is the container running on the source host The identifier, <image_name> is the name of the new image.

Then, export the image to a file:

$ docker save <image_name> -o <output_file>

Where, <image_name> is the name of the image to be exported, <output_file> is the path to the exported file.

Next, import the image file on the target host:

$ docker load -i <input_file>

Among them, <input_file> is the path of the imported image file.

Finally, run the imported image:

$ docker run -d <image_name>

3. Remote management of containers
   Docker provides a remote API that can manage containers and images through HTTP RESTful interfaces. You can use the curl command or write a script to achieve remote management of Docker.

First, you need to enable the remote API in the configuration file of the Docker service. Edit the /lib/systemd/system/docker.service file and change the ExecStart line to the following:

ExecStart=/usr/bin/dockerd -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock

Then, reload and restart the Docker service:

$ sudo systemctl daemon-reload
$ sudo systemctl restart docker

Then, you can use the curl command to send HTTP requests to achieve remote management of Docker. The following are some commonly used curl command examples:

• Get the version information of the Docker service:

  $ curl http://localhost:2375/version

• List all containers:

  $ curl http://localhost:2375/containers/json

• Start a container:

  $ curl -X POST http://localhost:2375/containers/create?name=<container_name> -d '{"Image":"<image_name>"}'
  $ curl -X POST http://localhost:2375/containers/<container_id>/start

• Stop a container:

  $ curl -X POST http://localhost:2375/containers/<container_id>/stop

• Delete a container:

  $ curl -X DELETE http://localhost:2375/containers/<container_id>

In addition to the curl command, you can also use programming languages ​​​​to achieve remote management of Docker. The following is a sample code using Python:

import requests

url = "http://localhost:2375/containers/json"
response = requests.get(url)
containers = response.json()
for container in containers:
    print(container["Names"][0])

This code will list the names of all containers.

Summary
Implementing rapid migration and remote management of containers on Linux through Docker can greatly facilitate the work of development and operation and maintenance personnel. Containers can be easily migrated and remotely managed in just a few simple steps. I hope the code examples provided in this article are helpful to you, and if you have any questions or concerns, please feel free to ask.

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