Docker CE Installation on CentOS

Docker CE Installation on CentOS:

For this minimum required version of CentOS 7 required for Docker and enabled with the centos-extras repository.

Uninstall old versions of docker if any 

Docker or docker-engine old versions along with associated dependencies should be uninstalled before proceeding for new installation:

$ sudo yum remove docker \
                  docker-client\
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-selinux \
                  docker-engine-selinux \
                  docker-engine


The contents of /var/lib/docker, including images, containers,volumes, and networks are preserved.

Installing Docker CE:

There are different ways of Docker CE installations:

1. Docker's repositories - recommended approach for easy upgrades
2. Download RPM package and instanll manually - if no internet access to the machine then it is recommended an approach
3. Use automated convenience scripts which docker provides.

To avoid disk space issues:

1. Login as root. On some hosted machines, sudo is "/usr/local/bin/sudo".
2. To avoid filling up, your / directory ( To avoid space issues)

• Remove /var/lib/docker directory.
• Create a new location for docker files, e.g. /u01/docker-env/docker
• sudo ln -s /u01/docker-env/docker /var/lib/docker

Alternatively,

• You can configure docker directory in /etc/sysconfig/docker using -g option

• # /etc/sysconfig/docker
OPTIONS='-g /u01/docker'



Install using repository:
=================

Setup the Docker repository in the machine before proceeding with the installation

Set up the repository

1. Install requires packages : yum-utils provides the yum-config-manager utility, and device-mapper-persistent-data and lvm2 are required by the devicemapper storage driver.

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

2.For stable build installer use the below command:

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

1. To install the latest version of docker CE

$sudo yum install docker-ce

If prompted to accept the GPE key verify that the fingerprint matches 060A 61C5 1B55 8A7F 742B 77AA C52F EB6B 621E 9F35, and if so, accept it.

Docker is installed but not started. The docker group is created, but no users are added to the group.

2. To install a specific version of Docker CE , list the available versions in the repo, then select and install:

a. List and sort the versions available in your repo. This example sorts results by version number , highest to lowest and is truncated:

$yum list docker-ce --showduplicates | sort -r

docker-ce.x86_64            18.03.0.ce-1.el7.centos             docker-ce-stable


$ sudo yum install docker-ce-<version string>

3. start Docker :

$sudo systemctl start docker

4. Verify that docker is installed correctly by running the hello-world image

$sudo docker run hello-world

The command downloads a test image and runs it in a container.

Docker Ce is intalled and running, you need to use sudo to run docker commands.

Install from a package:

1.Download .rpm file from the url : https://download.docker.com/linux/centos/7/x86_64/stable/Packages/

2.Install Docker CE

$sudo yum install /path/to/package.rpm

3.start Docker

$ sudo systemctl start docker

4.verify the docker is installer correctly by running the hello-world image

$sudo docker run hello-world

This command downloads a latest image and runs it in a container.

Upgrade docker CE:
Download newer package file and release installation procedure using yum -y upgrade instead of yum -y install.

Docker Basic commands

docker --version # to check docker version
docker version # detailed version
docker info # to see more details about docker installation

Docker Basic check for Version Installation

Uninstall Docker CE:
1. uninstall the Docker package:

$sudo yum remove docker-ce

2. Image, containers, volumes, or customized configuration files on your host are not automatically removed. To delete all images containers and volumes:

$ sudo rm -rf /var/lib/docker