Docker

Docker is an application that simplifies the process of managing application processes in containers . Containers let you run your applications in resource-isolated processes. They’re similar to virtual machines, but containers are more portable, more resource-friendly, and more dependent on the host operating system. 
 
 Installation 
 In this guide, you will install Docker Community Edition (CE) on Ubuntu 22.04. 
 To follow this tutorial, you will need the following: 
 
 One Ubuntu 22.04 server, including a sudo non- root user and a firewall. 
 An account on Docker Hub if you wish to create your own images and push them to Docker Hub. 
 
 The Docker installation package available in the official Ubuntu repository may not be the latest version. To ensure we get the latest version, we’ll install Docker from the official Docker repository. To do that, we’ll add a new package source, add the GPG key from Docker to ensure the downloads are valid, and then install the package. 
 First, update your existing list of packages: 
 sudo apt update 
 Next, install a few prerequisite packages which let apt use packages over HTTPS: 
 sudo apt install apt-transport-https ca-certificates curl software-properties-common 
 Then add the GPG key for the official Docker repository to your system: 
 curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg 
 Add the Docker repository to APT sources: 
 echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null 
 Update your existing list of packages again for the addition to be recognized: 
 sudo apt update 
 Make sure you are about to install from the Docker repo instead of the default Ubuntu repo: 
 apt-cache policy docker-ce 
 You’ll see output like this, although the version number for Docker may be different: 
 Output of apt-cache policy docker-ce 
 docker-ce:
 Installed: (none)
 Candidate: 5:20.10.14~3-0~ubuntu-jammy
 Version table:
 5:20.10.14~3-0~ubuntu-jammy 500
 500 https://download.docker.com/linux/ubuntu jammy/stable amd64 Packages
 5:20.10.13~3-0~ubuntu-jammy 500
 500 https://download.docker.com/linux/ubuntu jammy/stable amd64 Packages
 
 Notice that docker-ce is not installed, but the candidate for installation is from the Docker repository for Ubuntu 22.04 ( jammy ). 
 Finally, install Docker: 
 sudo apt install docker-ce 
 Docker should now be installed, the daemon started, and the process enabled to start on boot. Check that it’s running: 
 sudo systemctl status docker 
 The output should be similar to the following, showing that the service is active and running: 
 Output 
 ● docker.service - Docker Application Container Engine
 Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
 Active: active (running) since Fri 2022-04-01 21:30:25 UTC; 22s ago
TriggeredBy: ● docker.socket
 Docs: https://docs.docker.com
 Main PID: 7854 (dockerd)
 Tasks: 7
 Memory: 38.3M
 CPU: 340ms
 CGroup: /system.slice/docker.service
 └─7854 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
 
 Installing Docker now gives you not just the Docker service (daemon) but also the docker command line utility, or the Docker client.