As we discussed in the previous section, the Docker Hub repository typically hosts both official images as well as images that have been contributed by third-party Docker enthusiasts. At the time of writing this book, thousands of curated Docker images (also called the Dockerized application) were available for users. Most of them are downloaded by millions of users. These images can be used either as-is or as a building block for user-specific applications.

You can search for Docker images in the Docker Hub Registry using the docker search subcommand, as shown in this example:

$ sudo docker search mysql  

The search on mysql will list many mysql images, but we will limit it to just five lines by piping it with the head -10 command, as follows:

As you can see in the preceding search output excerpts, the images are ordered based on their star rating. The search result also indicates whether the image is an official image (curated and hosted by Docker Inc) or not. The search result also indicates whether the image is built using the automation framework provided by Docker Inc. The mysql image curated and hosted by Docker Inc has a 2759 star rating, which indicated that this is the most popular mysql image. We strongly recommend that you use the images that are officially hosted by Docker Inc for security reasons, otherwise make sure that the images are provided by trusted and well-known sources. The next image in the list is mysql-server, made available by the third party, mysql, with a 178 star rating. Docker containers are the standard building blocks of distributed applications.

A dynamic repository of Docker images is being realized with the help of the enthusiastic contribution of several community members across the Globe. Software engineers can download the images stocked in the Docker Hub and come out with different images and containers to exceptionally cater for differing business needs. This sort of arrangement is to elegantly automate and accelerate the building, deployment, and usage of software applications. The Docker Hub represents a community effort for providing a great base of images for applications, so that developers and system administrators can focus on building new features and functionalities, while minimizing their repetitive work on commodity scaffolding and plumbing.

Based on the search queries in the Docker Hub Registry and discussions with many of the developer community members, the Docker company, which spearheaded the Docker movement so powerfully and passionately, came to the conclusion that the developer community wanted prebuilt stacks of their favorite programming languages. Specifically, the developers wanted to get to work as quickly as possible, writing code without wasting time and wrestling with environments, scaffolding, and dependencies.