Install Docker on Centos 6.5 – 7 [64bit]

CentOS

Docker is supported on the following versions of CentOS:

• CentOS 7 (64-bit)
• CentOS 6.5 (64-bit) or later

These instructions are likely work for other binary compatible EL6/EL7 distributions such as Scientific Linux, but they haven’t been tested.

Please note that due to the current Docker limitations, Docker is able to run only on the 64 bit architecture.

Kernel support

Currently the CentOS project will only support Docker when running on kernels shipped by the distribution. There are kernel changes which will cause issues if one decides to step outside that box and run non-distribution kernel packages.

To run Docker on CentOS-6.5 or later, you will need kernel version 2.6.32-431 or higher as this has specific kernel fixes to allow Docker to run.

Installing Docker – CentOS-7

Docker is included by default in the CentOS-Extras repository. To install run the following command:

$ sudo yum install docker

Please continue with the Starting the Docker daemon.

FirewallD

CentOS-7 introduced firewalld, which is a wrapper around iptables and can conflict with Docker.

When firewalld is started or restarted it will remove the DOCKER chain from iptables, preventing Docker from working properly.

When using Systemd, firewalld is started before Docker, but if you start or restart firewalld after Docker, you will have to restart the Docker daemon.

Installing Docker – CentOS-6.5

For CentOS-6.5, the Docker package is part of Extra Packages for Enterprise Linux (EPEL) repository, a community effort to create and maintain additional packages for the RHEL distribution.

Firstly, you need to ensure you have the EPEL repository enabled. Please follow the EPEL installation instructions.

For CentOS-6, there is a package name conflict with a system tray application and its executable, so the Docker RPM package was called docker-io.

To proceed with docker-io installation on CentOS-6, you may need to remove the docker package first.

$ sudo yum -y remove docker

Next, let’s install the docker-io package which will install Docker on our host.

$ sudo yum install docker-io

Please continue with the Starting the Docker daemon.

Manual installation of latest Docker release

While using a package is the recommended way of installing Docker, the above package might not be the current release version. If you need the latest version, you can install the binary directly.

When installing the binary without a package, you may want to integrate Docker with Systemd. For this, install the two unit files (service and socket) from the GitHub repository to /etc/systemd/system.

Please continue with the Starting the Docker daemon.

Starting the Docker daemon

Once Docker is installed, you will need to start the docker daemon.

$ sudo service docker start

If we want Docker to start at boot, we should also:

$ sudo chkconfig docker on

Now let’s verify that Docker is working. First we’ll need to get the latest centos image.

$ sudo docker pull centos

Next we’ll make sure that we can see the image by running:

$ sudo docker images centos

This should generate some output similar to:

$ sudo docker images centos
REPOSITORY      TAG             IMAGE ID          CREATED             VIRTUAL SIZE
centos          latest          0b443ba03958      2 hours ago         297.6 MB

Run a simple bash shell to test the image:

$ sudo docker run -i -t centos /bin/bash

If everything is working properly, you’ll get a simple bash prompt. Type exit to continue.

Custom daemon options

If you need to add an HTTP Proxy, set a different directory or partition for the Docker runtime files, or make other customizations, read our Systemd article to learn how to customize your Systemd Docker daemon options.

Dockerfiles

The CentOS Project provides a number of sample Dockerfiles which you may use either as templates or to familiarize yourself with docker. These templates are available on GitHub at https://github.com/CentOS/CentOS-Dockerfiles

Done! You can either continue with the Docker User Guide or explore and build on the images yourself.

Issues?

If you have any issues – please report them directly in the CentOS bug tracker.