2. Docker Installation on Linux Machine
To start the installation of Docker, we are
going to use an Ubuntu instance. You can use Oracle Virtual Box to setup a
virtual Linux instance, in case you don’t have it already.
The following screenshot shows a simple Ubuntu server which has been
installed on Oracle Virtual Box. There is an OS user named demo which has been defined on the system having entire root access
to the sever.
To install Docker, we
need to follow the steps given below.
Step 1: Before installing
Docker, you first have to ensure that you have the right Linux kernel version running. Docker is only
designed to run on Linux kernel version 3.8 and higher. We can do this by
running the following command:
uname
This method returns the
system information about the Linux system.
Syntax
uname -a
Options
a – This
is used to ensure that the system information is returned.
Return Value
This method returns the
following information on the Linux system:
·
kernel name
·
node name
·
kernel release
·
kernel version
·
machine
·
processor
·
hardware platform
·
operating system
Example
uname –a
Output
When we run above
command, we will get the following result:
From
the output, we can see that the Linux kernel version is 4.2.0-27 which is
higher than version 3.8, so we are good to go.
Step 2: You need to update
the OS with the latest packages, which can be done via the following command:
apt-get
This method installs
packages from the Internet on to the Linux system.
Syntax
sudo apt-get
update
Options
·
sudo
- The sudo command is used
to ensure that the command runs with root
access.
·
update
- The update option is used
ensure that all packages are updated on the
Linux system.
Return Value
None
Example
sudo apt-get
update
Output
When we run the above
command, we will get the following result:
This command will connect to the internet and download the latest
system packages for Ubuntu.
Step 3: The next step is to
install the necessary certificates that will be required to work with the Docker site later on to
download the necessary Docker packages. It can be done with the following
command:
sudo apt-get
install apt-transport-https ca-certificates
Step 4: The next step is to
add the new GPG key. This key is required to ensure that all data is encrypted when downloading the
necessary packages for Docker.
The following command will download the key with the ID
58118E89F3A912897C070ADBF76221572C52609D from the keyserver hkp://ha.pool.sks-keyservers.net:80 and adds it to the adv keychain. Please note that this
particular key is required to download the necessary Docker packages.
sudo apt-key adv
\
--keyserver
hkp://ha.pool.sks-keyservers.net:80 \
--recv-keys
58118E89F3A912897C070ADBF76221572C52609D
Step 5: Next, depending on
the version of Ubuntu you have, you will need to add the relevant site to the docker.list
for the apt package manager, so that
it will be able to detect the Docker packages from the Docker site and download
them accordingly.
·
Precise
12.04 (LTS) ─ deb https://apt.dockerproject.org/repo ubuntu-precise main
·
Trusty 14.04 (LTS) ─ deb
https://apt.dockerproject.org/repo ubuntu-trusty main
·
Wily 15.10 ─ deb
https://apt.dockerproject.org/repo ubuntu-wily main
·
Xenial 16.04 (LTS) ─ deb
https://apt.dockerproject.org/repo ubuntu-xenial main
Since
our OS is Ubuntu 14.04, we will use the Repository name as “deb
https://apt.dockerproject.org/repo ubuntu-trusty main”
And then, we will need
to add this repository to the docker.list
as mentioned above.
echo "deb
https://apt.dockerproject.org/repo ubuntu-trusty main” |sudo
tee
/etc/apt/sources.list.d/docker.list
Step 6: Next, we issue the apt-get update command to update the
packages on the Ubuntu system.
Step 7: If you want to verify
that the package manager is pointing to the right repository, you can do it by issuing the apt-cache command.
apt-cache policy
docker-engine
Step 8: Issue the apt-get update command to ensure all
the packages on the local system are
up to date.
Step 9: For Ubuntu Trusty,
Wily, and Xenial, we have to install the linux-image-extra-* kernel packages, which allows one to
use the aufs storage driver. This
driver is used by the newer versions of Docker.
It can be done by using
the following command:
sudo apt-get
install linux-image-extra-$(uname -r) linux-image-extra-virtual
Step 10: The final step is to install Docker and we
can do this with the following command:
sudo apt-get
install –y docker-engine
Here, apt-get uses the
install option to download the Docker-engine image from the Docker website and
get Docker installed.
The Docker-engine is the official package from the Docker Corporation
for Ubuntu-based systems.
Docker Version-
To see the version of
Docker running, you can issue the following command:
Syntax
docker version
Options
·
version
– It is used to ensure the
Docker command returns the Docker version
installed.
Return Value
The output will provide
the various details of the Docker version installed on the system.
Example
sudo docker
version
Output
When we run the above
program, we will get the following result:
Docker Info
To
see more information on the Docker running on the system, you can issue the
following command:
Syntax
docker info
Options
·
info
– It is used to ensure that
the Docker command returns the detailed information
on the Docker service installed.
Return Value
The output will provide
the various details of the Docker installed on the system such as
·
Number of containers
·
Number of images
·
The storage driver used by Docker
·
The root directory used by Docker
·
The execution driver used by Docker
Example
sudo docker info
Output
When we run the above
command, we will get the following result:
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