Docker runs on CentOS 7.X. An installation on other binary compatible EL7 distributions such as Scientific Linux might succeed, but Docker does not test or support Docker on these distributions.
This page instructs you to install using Docker-managed release packages and installation mechanisms. Using these packages ensures you get the latest release of Docker. If you wish to install using CentOS-managed packages, consult your CentOS documentation.
Docker requires a 64-bit installation regardless of your CentOS version. Also, your kernel must be 3.10 at minimum, which CentOS 7 runs.
To check your current kernel version, open a terminal and use uname -r
to display your kernel version:
$ uname -r 3.10.0-229.el7.x86_64
Finally, it is recommended that you fully update your system. Please keep in mind that your system should be fully patched to fix any potential kernel bugs. Any reported kernel bugs may have already been fixed on the latest kernel packages.
There are two ways to install Docker Engine. You can install using the yum
package manager. Or you can use curl
with the get.docker.com
site. This second method runs an installation script which also installs via the yum
package manager.
Log into your machine as a user with sudo
or root
privileges.
Make sure your existing yum packages are up-to-date.
$ sudo yum update
Add the yum repo.
$ sudo tee /etc/yum.repos.d/docker.repo <<-'EOF' [dockerrepo] name=Docker Repository baseurl=https://yum.dockerproject.org/repo/main/centos/7/ enabled=1 gpgcheck=1 gpgkey=https://yum.dockerproject.org/gpg EOF
Install the Docker package.
$ sudo yum install docker-engine
Start the Docker daemon.
$ sudo service docker start
Verify docker
is installed correctly by running a test image in a container.
$ sudo docker run hello-world Unable to find image 'hello-world:latest' locally latest: Pulling from hello-world a8219747be10: Pull complete 91c95931e552: Already exists hello-world:latest: The image you are pulling has been verified. Important: image verification is a tech preview feature and should not be relied on to provide security. Digest: sha256:aa03e5d0d5553b4c3473e89c8619cf79df368babd1.7.1cf5daeb82aab55838d Status: Downloaded newer image for hello-world:latest Hello from Docker. This message shows that your installation appears to be working correctly. To generate this message, Docker took the following steps: 1. The Docker client contacted the Docker daemon. 2. The Docker daemon pulled the "hello-world" image from the Docker Hub. (Assuming it was not already locally available.) 3. The Docker daemon created a new container from that image which runs the executable that produces the output you are currently reading. 4. The Docker daemon streamed that output to the Docker client, which sent it to your terminal. To try something more ambitious, you can run an Ubuntu container with: $ docker run -it ubuntu bash For more examples and ideas, visit: http://docs.docker.com/userguide/
Log into your machine as a user with sudo
or root
privileges.
Make sure your existing yum packages are up-to-date.
$ sudo yum update
Run the Docker installation script.
$ curl -fsSL https://get.docker.com/ | sh
This script adds the docker.repo
repository and installs Docker.
Start the Docker daemon.
$ sudo service docker start
Verify docker
is installed correctly by running a test image in a container.
$ sudo docker run hello-world
The docker
daemon binds to a Unix socket instead of a TCP port. By default that Unix socket is owned by the user root
and other users can access it with sudo
. For this reason, docker
daemon always runs as the root
user.
To avoid having to use sudo
when you use the docker
command, create a Unix group called docker
and add users to it. When the docker
daemon starts, it makes the ownership of the Unix socket read/writable by the docker
group.
Warning: The
docker
group is equivalent to theroot
user; For details on how this impacts security in your system, see Docker Daemon Attack Surface for details.
To create the docker
group and add your user:
Log into Centos as a user with sudo
privileges.
Create the docker
group.
sudo groupadd docker
Add your user to docker
group.
sudo usermod -aG docker your_username
Log out and log back in.
This ensures your user is running with the correct permissions.
Verify your work by running docker
without sudo
.
$ docker run hello-world
To ensure Docker starts when you boot your system, do the following:
$ sudo chkconfig docker on
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.
You can uninstall the Docker software with yum
.
List the package you have installed.
$ yum list installed | grep docker yum list installed | grep docker docker-engine.x86_64 1.7.1-1.el7 @/docker-engine-1.7.1-1.el7.x86_64.rpm
Remove the package.
$ sudo yum -y remove docker-engine.x86_64
This command does not remove images, containers, volumes, or user-created configuration files on your host.
To delete all images, containers, and volumes, run the following command:
$ rm -rf /var/lib/docker
Locate and delete any user-created configuration files.