How to Install Docker on CentOS 7 & RHEL 7

Docker is container-based application framework, which wrap of a specific application with all its dependencies in a container. Docker containers can easily to ship to a remote location on start there without making entire application setup. This tutorial will help you to install and manage Docker on CentOS/RHEL 7/6 operating system.

Step 1 – Verify Requirements

For a standard installation, Docker required 64-bit operating system having Kernel >= 3.10 version. Older versions of Kernel have some missing requirements to run all features of Docker.

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uname -r

3.19.0-49-generic

Also install the following packages on your system.

sudo yum install -y yum-utils device-mapper-persistent-data lvm2

Step 2 – Add Docker Yum Repository

Let’s add the official Docker yum repository on your system.

sudo yum config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

Step 3 – Install Docker on CentOS 7

After adding the yum repository to your CentOS system, update the yum cache by executing the following command.

sudo yum makecache fast

Now install docker community edition package to install docker on your system. This is installed many of required decencies on your system.

sudo yum install docker-ce

After successful installation of Docker engine, Let’s start the docker service.

sudo systemctl start docker.service

Then check the status of the Docker service.

Docker has been installed and running on your system. You can visit our Docker tutorial section to work with Docker containers.

How to Use Docker?

Search Docker Images

First of all search Docker container images from Docker hub. For example, below command will search all images with Ubuntu and list as output

sudo docker search centos

Download Docker Images

Now download the Docker container with name Ubuntu on your local system using following commands.

sudo docker pull ubuntu

latest: Pulling from library/ubuntu

fa5be2806d4c: Pull complete
b4af4261cb15: Downloading [==>               ] 3.779 MB/70.55 MB
5d358abc5d9c: Download complete
2933d50b9f77: Download complete

Now make sure that above images have been downloaded successfully on your system. Below command list all images.

sudo docker images

REPOSITORY  TAG            IMAGE ID            CREATED             VIRTUAL SIZE
ubuntu      latest         36248ae4a9ac        2 days ago          188 MB
centos      latest         2933d50b9f77        2 days ago          196.6 MB

Launch New Container with Image

Finally, launch a Docker container using the above-downloaded image on your system. Below command will start a new container and provide you access to that container with /bin/bash shell.

docker run -i -t ubuntu /bin/bash

To exit from docker container type CTRL + P + Q. This will leave container running in the background an provide you host system console. If you used exit command, it will stop the current container.

After exiting from Docker container, execute below command to list all running containers.

docker ps

CONTAINER ID     IMAGE     COMMAND        CREATED        STATUS        PORTS    NAMES
f2582758af13     ubuntu    "/bin/bash"    2 hours ago    Up 2 hours             first_ubuntu

By default Above command will list only running containers. To list all containers (including stopped container) use the following command.

docker ps -a

Start/Stop/Attach Container

You can start, stop or attach to any containers with following commands. To start container use following command.

docker start CONTAINER_ID

To stop container use following command.

docker stop CONTAINER_ID

To attach to currently running container use following command.

docker attach CONTAINER_ID