Installation on Debian (Engine)

Debian

Docker is supported on the following versions of Debian:

• Debian testing stretch (64-bit)
• Debian 8.0 Jessie (64-bit)
• Debian 7.7 Wheezy (64-bit) (backports required)

Note: If you previously installed Docker using APT, make sure you update your APT sources to the new APT repository.

Prerequisites

Docker requires a 64-bit installation regardless of your Debian version. Additionally, your kernel must be 3.10 at minimum. The latest 3.10 minor version or a newer maintained version are also acceptable.

Kernels older than 3.10 lack some of the features required to run Docker containers. These older versions are known to have bugs which cause data loss and frequently panic under certain conditions.

To check your current kernel version, open a terminal and use uname -r to display your kernel version:

 $ uname -r

Additionally, for users of Debian Wheezy, backports must be available. To enable backports in Wheezy:

1. Log into your machine and open a terminal with sudo or root privileges.

2. Open the /etc/apt/sources.list.d/backports.list file in your favorite editor.

   If the file doesn’t exist, create it.

3. Remove any existing entries.

4. Add an entry for backports on Debian Wheezy.

   An example entry:

    deb http://http.debian.net/debian wheezy-backports main
   

5. Update package information:

    $ apt-get update
   

Update your apt repository

Docker’s APT repository contains Docker 1.7.1 and higher. To set APT to use from the new repository:

1. If you haven’t already done so, log into your machine as a user with sudo or root privileges.

2. Open a terminal window.

3. Purge any older repositories.

    $ apt-get purge lxc-docker*
    $ apt-get purge docker.io*
   

4. Update package information, ensure that APT works with the https method, and that CA certificates are installed.

    $ apt-get update
    $ apt-get install apt-transport-https ca-certificates
   

5. Add the new GPG key.

    $ apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
   

6. Open the /etc/apt/sources.list.d/docker.list file in your favorite editor.

   If the file doesn’t exist, create it.

7. Remove any existing entries.

8. Add an entry for your Debian operating system.

   The possible entries are:

   • On Debian Wheezy

     deb https://apt.dockerproject.org/repo debian-wheezy main
     

   • On Debian Jessie

     deb https://apt.dockerproject.org/repo debian-jessie main
     

   • On Debian Stretch/Sid

     deb https://apt.dockerproject.org/repo debian-stretch main
     

   Note: Docker does not provide packages for all architectures. To install docker on a multi-architecture system, add an [arch=...] clause to the entry. Refer to the Debian Multiarch wiki for details.

9. Save and close the file.

10. Update the APT package index.

     $ apt-get update
    

11. Verify that APT is pulling from the right repository.

     $ apt-cache policy docker-engine
    

    From now on when you run apt-get upgrade, APT pulls from the new apt repository.

Install Docker

Before installing Docker, make sure you have set your APT repository correctly as described in the prerequisites.

1. Update the APT package index.

   $ sudo apt-get update
   

2. Install Docker.

   $ sudo apt-get install docker-engine
   

3. Start the docker daemon.

   $ sudo service docker start
   

4. Verify docker is installed correctly.

   $ sudo docker run hello-world
   

   This command downloads a test image and runs it in a container. When the container runs, it prints an informational message. Then, it exits.

Giving non-root access

The docker daemon always runs as the root user and 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 so, by default, you can access it with sudo.

If you (or your Docker installer) create a Unix group called docker and add users to it, then the docker daemon will make the ownership of the Unix socket read/writable by the docker group when the daemon starts. The docker daemon must always run as the root user, but if you run the docker client as a user in the docker group then you don’t need to add sudo to all the client commands. From Docker 0.9.0 you can use the -G flag to specify an alternative group.

Warning: The docker group (or the group specified with the -G flag) is root-equivalent; see Docker Daemon Attack Surface details.

Example:

# Add the docker group if it doesn't already exist.
$ sudo groupadd docker

# Add the connected user "${USER}" to the docker group.
# Change the user name to match your preferred user.
# You may have to logout and log back in again for
# this to take effect.
$ sudo gpasswd -a ${USER} docker

# Restart the Docker daemon.
$ sudo service docker restart

Upgrade Docker

To install the latest version of Docker with apt-get:

$ apt-get upgrade docker-engine

Uninstall

To uninstall the Docker package:

$ sudo apt-get purge docker-engine

To uninstall the Docker package and dependencies that are no longer needed:

$ sudo apt-get autoremove --purge docker-engine

The above commands will not remove images, containers, volumes, or user created configuration files on your host. If you wish to delete all images, containers, and volumes run the following command:

$ rm -rf /var/lib/docker

You must delete the user created configuration files manually.

What next?

Continue with the User Guide.