====== Docker - Install Docker ======

===== Check the kernel version and the OS architecture =====

Run **uname -a** to check the version of the currently running Linux kernel:

<code bash>
uname -a
</code>

Check that it's a 64Bit Kernel (x86_64).  Docker won't work without this.

----

Check the Ubuntu version.

<code bash>
cat /etc/lsb-release
</code>

The command shows that the Ubuntu version is 16.04.

----

It is recommended to update Ubuntu before you install new software. Run the following command to fetch the latest updates from the Ubuntu repository and install them.

<code bash>
sudo apt update
sudo upgrade
</code>

----

Now install docker with the apt command:

<code bash>
sudo apt install -y docker.io
</code>

Wait until the installation has been completed.

----

===== Add your user to the docker group =====

<code bash>
sudo usermod -aG docker $USER
</code>

<WRAP info>
**NOTE:**  This allows docker to be run without using sudo.

To enable this functionality, log out and log back in; or run: <code bash>
newgrp docker
</code>

</WRAP>

----

===== Verify that you can run docker commands without sudo =====

<code bash>
docker run hello-world
</code>

<WRAP info>
**NOTE:**  If an error is seen such as **docker: Got permission denied while trying to connect to the Docker daemon socket**, then:

<code bash>
sudo chmod 666 /var/run/docker.sock
</code>

</WRAP>


----

===== Start Docker =====

<code bash>
systemctl start docker
</code>

----

===== Enable docker to run at system boot =====

<code bash>
systemctl enable docker
</code>

----

===== Check the docker version =====

<code bash>
docker version
</code>

Show the currently installed Docker version.

----

<WRAP info>
**NOTE:**  docker is now installed.

  * A container can now be started by downloading a Docker Image from the Docker Registry.

</WRAP>