How to Install and Manage Docker on CentOS/RHEL 7/6

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 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.

1. Verify Requirements

For 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.

# uname -r  3.19.0-49-generic 

2. Add Docker Yum Repository

Let’s add the Docker yum repository on your system. Create a new yum configuration file /etc/yum.repos.d/docker.repo

# vim /etc/yum.repos.d/docker.repo 

and following contents.

[Docker] name=Docker Repository baseurl=https://yum.dockerproject.org/repo/main/centos/$releasever/ enabled=1 gpgcheck=1 gpgkey=https://yum.dockerproject.org/gpg 

3. Install Docker

First update all packages on your system using following command.

# yum update 

Now install docker-engine package to install docker on your system. This is install many of required decencies on your system.

# yum install docker-engine 

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

# service docker start 

4. Manage Docker Container

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

# docker search centos 

Download Docker Images

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

# 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 has been downloaded successfully on your system. Below command list all images.

# 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 above downloaded image on your system. Below command will start a new container and provide you access of 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 background an provide you host system console. If you used exit command, it will stop the current container.
After existing 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 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> 

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