what is docker hub

Docker hub is a public warehouse officially maintained by Docker, which already includes more than 2,650,000 images; most needs can be met by downloading images directly from Docker Hub.

The operating environment of this article: centOS6.8 system, Docker version 18.09.x, Dell G3 computer.

What is docker hub?

Currently, Docker officially maintains a public warehouse Docker Hub, which already includes more than 2,650,000 images. Most needs can be achieved by downloading the image directly from Docker Hub.

Docker Hub address: https://hub.docker.com/

Login

You can enter the user interactively by executing the docker login command name and password to complete logging into Docker Hub through the command line interface.

You can log out through docker logout.

Pull the image

You can use the docker search command to find the image in the official warehouse, and use the docker pull command to download it locally.

For example, search with centos as the keyword:

$ docker search centos
NAME                               DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
centos                             The official build of CentOS.                   6449      [OK]
ansible/centos7-ansible            Ansible on Centos7                              132                  [OK]
consol/centos-xfce-vnc             Centos container with "headless" VNC session…   126                  [OK]
jdeathe/centos-ssh                 OpenSSH / Supervisor / EPEL/IUS/SCL Repos - …   117                  [OK]
centos/systemd                     systemd enabled base container.                 96                   [OK]

You can see that many images containing keywords are returned, including the image name, description, and collection number (indicating that the image is of concern level), whether it is officially created (OFFICIAL), whether it is automatically built (AUTOMATED).

Mirrors can be divided into two categories depending on whether they are officially provided.

One is an image like centos, which is called a base image or root image. These base images are created, verified, supported, and provided by Docker Company. Such images often use a single word as their name.

There is also a type, such as ansible/centos7-ansible image, which is created and maintained by a registered user of Docker Hub, often with a user name prefix. You can specify to use the image provided by a certain user through the prefix username/, such as the ansible user.

In addition, when searching, you can use the --filter=stars=N parameter to specify that only images with a collection number of N or more will be displayed.

Download the official centos image locally.

$ docker pull centos
Using default tag: latest
latest: Pulling from library/centos
7a0437f04f83: Pull complete
Digest: sha256:5528e8b1b1719d34604c87e11dcd1c0a20bedf46e83b5632cdeac91b8c04efc1
Status: Downloaded newer image for centos:latest
docker.io/library/centos:latest

Push image

Users can also push their own image to Docker Hub through the docker push command after logging in.

Please replace username in the following command with your Docker account username.

$ docker tag ubuntu:18.04 username/ubuntu:18.04
$ docker image ls
REPOSITORY                                               TAG                    IMAGE ID            CREATED             SIZE
ubuntu                                                   18.04                  275d79972a86        6 days ago          94.6MB
username/ubuntu                                          18.04                  275d79972a86        6 days ago          94.6MB
$ docker push username/ubuntu:18.04
$ docker search username
NAME                      DESCRIPTION                                     STARS               OFFICIAL            AUTOMATED
username/ubuntu

Automatic build (after June 18, 2021, this feature will only be available to paid users.)

Recommended learning: "docker video tutorial"

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