This assumes you have installed Docker on Linux and Docker is running.

A Docker image contains the code used to create a Docker container, such as creating a Nginx web server, or a mySQL server, or a home grown app, and the list goes on. In this way, an image is like a template used to create a container. An image is kind of like a virtual machine, but much more light weight, using significantly less storage a memory (containers are usually megabytes in size).

The docker search command is used to list images that can be installed. In this example, the docker search command is used to list the mySQL images that can be installed.

docker search mysql

Or to search a specific registry.

docker search registry.example.com:8000/v1/_catalog

docker search registry.example.com:8000/v2/_catalog

docker search registry.example.com:8000/library

Following is an example of what may be returned. Typically, folks are looking to install an official image, thus you are looking at the images that have OK in the OFFICIAL column. You can then use the docker create command to install an image.

INDEX       NAME                                        DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
docker.io   docker.io/mysql                             MySQL is a widely used, open-source relati...   9106      [OK]       
docker.io   docker.io/mariadb                           MariaDB is a community-developed fork of M...   3217      [OK]       
docker.io   docker.io/mysql/mysql-server                Optimized MySQL Server Docker images. Crea...   674                  [OK]
docker.io   docker.io/centos/mysql-57-centos7           MySQL 5.7 SQL database server                   67                   
docker.io   docker.io/centurylink/mysql                 Image containing mysql. Optimized to be li...   61                   [OK]
docker.io   docker.io/mysql/mysql-cluster               Experimental MySQL Cluster Docker images. ...   61                   
docker.io   docker.io/deitch/mysql-backup               REPLACED! Please use http://hub.docker.com...   41                   [OK]
docker.io   docker.io/bitnami/mysql                     Bitnami MySQL Docker Image                      35                   [OK]
docker.io   docker.io/tutum/mysql                       Base docker image to run a MySQL database ...   34                   
docker.io   docker.io/schickling/mysql-backup-s3        Backup MySQL to S3 (supports periodic back...   29                   [OK]
docker.io   docker.io/prom/mysqld-exporter                                                              26                   [OK]
docker.io   docker.io/linuxserver/mysql                 A Mysql container, brought to you by Linux...   24                   
docker.io   docker.io/centos/mysql-56-centos7           MySQL 5.6 SQL database server                   19                   
docker.io   docker.io/circleci/mysql                    MySQL is a widely used, open-source relati...   17                   
docker.io   docker.io/mysql/mysql-router                MySQL Router provides transparent routing ...   14                   
docker.io   docker.io/arey/mysql-client                 Run a MySQL client from a docker container      13                   [OK]
docker.io   docker.io/databack/mysql-backup             Back up mysql databases to... anywhere!         10                   
docker.io   docker.io/openshift/mysql-55-centos7        DEPRECATED: A Centos7 based MySQL v5.5 ima...   6                    
docker.io   docker.io/fradelg/mysql-cron-backup         MySQL/MariaDB database backup using cron t...   4                    [OK]
docker.io   docker.io/genschsa/mysql-employees          MySQL Employee Sample Database                  4                    [OK]
docker.io   docker.io/ansibleplaybookbundle/mysql-apb   An APB which deploys RHSCL MySQL                2                    [OK]
docker.io   docker.io/devilbox/mysql                    Retagged MySQL, MariaDB and PerconaDB offi...   2                    
docker.io   docker.io/jelastic/mysql                    An image of the MySQL database server main...   1                    
docker.io   docker.io/monasca/mysql-init                A minimal decoupled init container for mysql    0                    
docker.io   docker.io/widdpim/mysql-client              Dockerized MySQL Client (5.7) including Cu...   0                    [OK]