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Get Docker CE for Ubuntu

Published 10/14/2017
Estimated reading time: 10 minutes
To get started with Docker CE on Ubuntu, make sure youmeet the prerequisites, theninstall Docker.

Prerequisites

Docker EE customers

To install Docker Enterprise Edition (Docker EE), go toGet Docker EE for Ubuntuinstead of this topic.
To learn more about Docker EE, seeDocker Enterprise Edition.

OS requirements

To install Docker CE, you need the 64-bit version of one of these Ubuntuversions:
  • Zesty 17.04
  • Xenial 16.04 (LTS)
  • Trusty 14.04 (LTS)
Docker CE is supported on Ubuntu on x86_64, armhf, and s390x (IBM zSystems) architectures.
s390xlimitations: System Z is only supported on Ubuntu Xenial and Zesty.

Uninstall old versions

Older versions of Docker were called docker or docker-engine. If these areinstalled, uninstall them:
$ sudo apt-get remove docker docker-engine docker.io
It’s OK if apt-get reports that none of these packages are installed.
The contents of /var/lib/docker/, including images, containers, volumes, andnetworks, are preserved. The Docker CE package is now called docker-ce.

Recommended extra packages for Trusty 14.04

Unless you have a strong reason not to, install thelinux-image-extra-* packages, which allow Docker to use the aufs storagedrivers.
$ sudo apt-get update
$ sudo apt-get install \
linux-image-extra-$(uname -r) \
linux-image-extra-virtual
For Ubuntu 16.04 and higher, the Linux kernel includes support for OverlayFS,and Docker CE will use the overlay2 storage driver by default.

Install Docker CE

You can install Docker CE in different ways, depending on your needs:
  • Most usersset up Docker’s repositories and installfrom them, for ease of installation and upgrade tasks. This is therecommended approach.
  • Some users download the DEB package andinstall it manually and manageupgrades completely manually. This is useful in situations such as installingDocker on air-gapped systems with no access to the internet.
  • In testing and development environments, some users choose to use automatedconvenience scripts to install Docker.

Install using the repository

Before you install Docker CE for the first time on a new host machine, you need toset up the Docker repository. Afterward, you can install and update Docker fromthe repository.

Set up the repository

  1. Update the apt package index:

    $ sudo apt-get update

  2. Install packages to allow apt to use a repository over HTTPS:

    $ sudo apt-get install \
    apt-transport-https \
    ca-certificates \
    curl \
    software-properties-common

  3. Add Docker’s official GPG key:

    $ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add –

    Verify that you now have the key with the fingerprint9DC8 5822 9FC7 DD38 854A E2D8 8D81 803C 0EBF CD88, by searching for thelast 8 characters of the fingerprint.

    $ sudo apt-key fingerprint 0EBFCD88

    pub 4096R/0EBFCD88 2017-02-22
    Key fingerprint = 9DC8 5822 9FC7 DD38 854A E2D8 8D81 803C 0EBF CD88
    uid Docker Release (CE deb) <[email protected]>
    sub 4096R/F273FCD8 2017-02-22

  4. Use the following command to set up the stable repository. You alwaysneed the stable repository, even if you want to install builds from theedge or test repositories as well. To add the edge ortest repository, add the word edge or test (or both) after theword stable in the commands below.

    Note: The lsb_release -cs sub-command below returns the name of yourUbuntu distribution, such as xenial. Sometimes, in a distributionlike Linux Mint, you might have to change $(lsb_release -cs)to your parent Ubuntu distribution. For example, if you are using Linux Mint Rafaela, you could use trusty.

    amd64:

    $ sudo add-apt-repository \
    “deb [arch=amd64] https://download.docker.com/linux/ubuntu \$(lsb_release -cs)\
    stable”

    armhf:

    $ sudo add-apt-repository \
    “deb [arch=armhf] https://download.docker.com/linux/ubuntu \$(lsb_release -cs)\
    stable”

    s390x:

    $ sudo add-apt-repository \
    “deb [arch=s390x] https://download.docker.com/linux/ubuntu \$(lsb_release -cs)\
    stable”

    Note: Starting with Docker 17.06, stable releases are also pushed tothe edge and test repositories.

    Learn about stable and edge channels.

Install Docker CE

  1. Update the apt package index.

    $ sudo apt-get update

  2. Install the latest version of Docker CE, or go to the next step to install aspecific version. Any existing installation of Docker is replaced.

    $ sudo apt-get install docker-ce

    Got multiple Docker repositories?

    If you have multiple Docker repositories enabled, installingor updating without specifying a version in the apt-get install orapt-get update command will always install the highest possible version,which may not be appropriate for your stability needs.

  3. On production systems, you should install a specific version of Docker CEinstead of always using the latest. This output is truncated. List theavailable versions.

    $ apt-cache madison docker-ce

    docker-ce | 17.09.0~ce-0~ubuntu | https://download.docker.com/linux/ubuntu xenial/stable amd64 Packages

    The contents of the list depend upon which repositories are enabled. Choosea specific version to install. The second column is the version string. Thethird column is the repository name, which indicates which repository thepackage is from and by extension its stability level. To install a specificversion, append the version string to the package name and separate them byan equals sign (=):

    $ sudo apt-get install docker-ce=<VERSION>

    The Docker daemon starts automatically.

  4. Verify that Docker CE is installed correctly by running the hello-worldimage.

    $ sudo docker run hello-world

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

Docker CE is installed and running. You need to use sudo to run Docker commands.Continue to Linux postinstallto allownon-privileged users to run Docker commands and for other optional configurationsteps.

Upgrade Docker CE

To upgrade Docker CE, first run sudo apt-get update, then follow theinstallation instructions, choosing the new version you wantto install.

Install from a package

If you cannot use Docker’s repository to install Docker CE, you can download the.deb file for your release and install it manually. You will need to downloada new file each time you want to upgrade Docker CE.
  1. Go to https://download.docker.com/linux/ubuntu/dists/,choose your Ubuntu version, browse to pool/stable/ and choose amd64,armhf, or s390x. Download the .deb file for the Docker version youwant to install.

    Note: To install an edge package, change the wordstable in the URL to edge.Learn about stable and edge channels.

  2. Install Docker CE, changing the path below to the path where you downloadedthe Docker package.

    $ sudo dpkg -i /path/to/package.deb

    The Docker daemon starts automatically.

  3. Verify that Docker CE is installed correctly by running the hello-worldimage.

    $ sudo docker run hello-world

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

Docker CE is installed and running. You need to use sudo to run Docker commands.Continue to Post-installation steps for Linuxto allownon-privileged users to run Docker commands and for other optional configurationsteps.

Upgrade Docker CE

To upgrade Docker CE, download the newer package file and repeat theinstallation procedure, pointing to the new file.

Install using the convenience script

Docker provides convenience scripts at get.docker.comand test.docker.com for installing stable andtesting versions of Docker CE into development environments quickly andnon-interactively. The source code for the scripts is in thedocker-installrepository.Using these scripts is not recommended for productionenvironments, and you should understand the potential risks before you usethem:
  • The scripts require root or sudo privileges in order to run. Therefore,you should carefully examine and audit the scripts before running them.
  • The scripts attempt to detect your Linux distribution and version andconfigure your package management system for you. In addition, the scripts donot allow you to customize any installation parameters. This may lead to anunsupported configuration, either from Docker’s point of view or from your ownorganization’s guidelines and standards.
  • The scripts install all dependencies and recommendations of the packagemanager without asking for confirmation. This may install a large number ofpackages, depending on the current configuration of your host machine.
  • Do not use the convenience script if Docker has already been installed on thehost machine using another mechanism.
This example uses the script at get.docker.com toinstall the latest stable release of Docker CE on Linux. To install the latesttesting version, use test.docker.cominstead. Ineach of the commands below, replace each occurrence of get with test.
Warning:
Always examine scripts downloaded from the internet beforerunning them locally.
$ curl -fsSL get.docker.com -o get-docker.sh
$ sudo sh get-docker.sh
<output truncated>
If you would like to use Docker as a non-root user, you should now consider
adding your user to the “docker” group with something like:
sudo usermod -aG docker your-user
Remember that you will have to log out and back in for this to take effect!
WARNING: Adding a user to the “docker” group will grant the ability to run
containers which can be used to obtain root privileges on the
docker host.
Refer to https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface
for more information.
Docker CE is installed. It starts automatically on DEB-based distributions. OnRPM-based distributions, you need to start it manually using the appropriatesystemctl or service command. As the message indicates, non-root users arenot able to run Docker commands by default.

Upgrade Docker after using the convenience script

If you installed Docker using the convenience script, you should upgrade Dockerusing your package manager directly. There is no advantage to re-running theconvenience script, and it can cause issues if it attempts to re-addrepositories which have already been added to the host machine.

Uninstall Docker CE

  1. Uninstall the Docker CE package:

    $ sudo apt-get purge docker-ce

  2. Images, containers, volumes, or customized configuration files on your hostare not automatically removed. To delete all images, containers, andvolumes:

    $ sudo rm -rf /var/lib/docker

You must delete any edited configuration files manually.

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