Linux

Creating a Docker container from an existing image

by nschoonover

In this tutorial we will go over how to search and pull down an existing docker image from the docker hub to run it on your server or local system.

Prerequisites

  • You will need to have docker running and installed on your system.

Searching the Docker Hub

  • You can search the Docker Hub for pre made images. These images are either made by the community, or official builds of different projects. 
    docker search centos
  • You will get the following response. Notice what it shows you. This will include the following:

  1. A description
  2. Number of stars voted by the community
  3. Indication if the image is official and built by the organization in charge of the project
  4. Indication if the build is automated or not
  • Below is an example of what you will see when searching the Docker Hub.

docker_search

  • Notice the first image is marked as the official CentOS docker image.

Creating a container from a remote image

  • Let’s create a container based on the official CenOS build. 
    docker run -dit docker.io/centos

docker_run

  • Note, Docker will automatically download the image from the Docker Hub if the image is not installed on the host. Once completed, the image will be ran.

  • Here are the what the flags used in the previous command do:

Flag Function
-d Run container in background
-i Keep STDIN open, even if not attached
-t Allocate a pseudo-TTY

View running containers

  • Validate the container is running by getting a list of all running containers: 
    docker ps

docker_ps

In our next tutorial we will go over how to attach to a container.