Getting Started with Docker Guide – Linux

Install Docker CE

You can install Docker CE in different ways, depending on your needs:

• Most users set up Docker’s repositories and install from them, for ease of installation and upgrade tasks. This is the recommended approach.
• Some users download the DEB package and install it manually and manage upgrades completely manually. This is useful in situations such as installing Docker on air-gapped systems with no access to the internet.

Install using the repository

Before you install Docker CE for the first time on a new host machine, you need to set up the Docker repository. Afterward, you can install and update Docker from the 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 the key fingerprint is 9DC8 5822 9FC7 DD38 854A E2D8 8D81 803C 0EBF CD88.

   $ 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 always need the stable repository, even if you want to install builds from the edge or testing repositories as well. To add the edge or testing repository, add the word edge or testing (or both) after the word stable in the commands below.
   

   Note: The lsb_release -cs sub-command below returns the name of your Ubuntu distribution, such as xenial.

   Sometimes, in a distribution like 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 to the edge and testing 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 a specific version. Any existing installation of Docker is replaced.

   $ sudo apt-get install docker-ce
   

   Warning: If you have multiple Docker repositories enabled, installing or updating without specifying a version in the apt-get install or apt-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 CE instead of always using the latest. This output is truncated. List the available versions.

   $ apt-cache madison docker-ce
   
   docker-ce | 17.06.0~ce-0~ubuntu-xenial | https://download.docker.com/linux/ubuntu xenial/stable amd64 Packages
   

   The contents of the list depend upon which repositories are enabled, and will be specific to your version of Ubuntu (indicated by the xenial suffix on the version, in this example). Choose a specific version to install. The second column is the version string. The third column is the repository name, which indicates which repository the package is from and by extension its stability level. To install a specific version, append the version string to the package name and separate them by an 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-world image.

   $ 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 and exits.

Docker CE is installed and running. You need to use sudo to run Docker commands. Continue to Linux postinstall to allow non-privileged users to run Docker commands and for other optional configuration steps.

Upgrade Docker CE

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