Docker is a container technology used to run containers in Linux, Windows systems with little system resources. In this tutorial, we will examine how to install Docker and run containers in
apt based distros like Ubuntu, Debian, Mint, Kali, etc.
Update Apt Repository Information
The best practice before installing a package from a package repository is updating the repository information and getting the latest changes. We will start updating the repository with
apt update or
apt-get update command like below.
$ sudo apt update
$ sudo apt-get update
Install Docker From Ubuntu Repository
Rpm or Yum based distributions like RedHat, CentOS, Fedora uses
docker as package names without a problem. Because there is no collusion with the name
docker . But
apt based distributions like Ubuntu, Debian, Mint, Kali have some restriction because
docker package name is used by other application. So we need to use
docker.io as package name while installing the Docker.
$ sudo apt install docker.io
$ sudo apt-get install docker.io
Install Docker From Official Docker Repository
Docker is also provided as Ubuntu packages from the official Docker repository. Docker repository provides the latest version as it is the creator of the Docker packages. First, we will add GPG keys for the official Docker repository to the current system. We will use
apt-key commands like below.
$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add
Now we can add official Docker Ubuntu repository with the
add-apt-repository command like below.
$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
Now everything is ready to install Docker on Ubuntu. Before installing the official Docker we can print some information about it with the
apt show command like below. The package name provided by Docker will be
docker-ce which is different from the Ubuntu provided Docker which is
docker.io. But most of the things are the same.
$ apt show docker-ce
We can see that information like the package name, version, installed-size, etc is provided.
We can install the Docker package with the following command. We will use
sudo command in order to install the package.
$ sudo apt install docker-ce
Start Docker Service
Docker works as a service that is named
docker for all Docker installation. We can start the Docker service in order to use Docker, create containers, etc. We can start the Docker service with the following command. Docker service start will require
root privileges which can be provided with the
sudo command or current user password will be asked.
$ sudo systemctl start docker
$ systemctl start docker
Stop Docker Server
We can stop the Docker server if we do not want to use or to reload it by stopping and starting. We will use the following command.
$ sudo systemctl stop docker
$ systemctl stop docker
Print Docker Service Status
As Docker runs as a service if there is a problem by creating, running, saving docker containers we generally look to the Docker service status. We can print Docker service status with the following command.
$ systemctl status docker
We can see that Docker service is currently active or running from the given time. Information like Process ID, Task count, Memory usage, and last logs about the service is also provided.
Print Docker Version
Some features are provided upward from the given version. So if we want o use a feature with a given version number we need to know the current version of the Docker installation. We can print the Docker version with the
--version option like below.
$ docker --version
Search Docker Images
Generally, the first actions after installing Docker is searching for some images in order to download. We will use the command
docker for most of the operations like search. In this example, we will search the images named or tagged with the term
$ docker search centos
Download Docker Image
We can download or pull specific image before using it. We will use the
pull command which will download the image but do not start any container. In this example, we will pull the image named
$ docker pull centos
List Docker Images
Before downloading an image or in order to learn locally existing images we can use
docker images command which will list currently downloaded and existing images.
$ docker images
Create and Run Sample CentOS Container
Creating a container is the same for all distributions. We will use
docker command for this. We do not use
docker.io because it is not a command just a package name. In this example, we will run a bash shell in
CentOS container interactively. We need to be in
docker group or have root privileges in order to run Docker containers. So
$ sudo docker run -t -i centos bash
List Running Docker Containers
We can run multiple Docker containers at the same time. If we want to list currently running Docker containers we can use
docker ps command which will list only running Docker containers.
$ docker ps
Stop Running Docker Container
In the end, we want to stop a container we do not need for now. We can use
stopcommand of the Docker like below. We also need to provide Docker ID which can be obtained with the Docker running container list command.
$ sudo docker stop 1e4adf4c3c84