Welcome to Day 7 of the #90DaysOfDevOps challenge! Package managers are great tools for software management. These utilities streamline the process of installing, updating, and removing software packages on an operating system. In this article, we will explore how to do an installation using package managers. We will also explore the systemctl command.

Understanding Package Managers: Package managers serve as the bridge between users and software packages. They facilitate tasks such as installation, removal, and updates of software components. Whether it's a graphical software center or a command-line tool like apt-get or yum, package managers simplify the software management process.

Ubuntu uses the APT (Advanced Package Tool) package manager as its primary tool for managing software installations. However, various other operating systems and Linux distributions employ different package managers for similar purposes. For instance, macOS relies on the Homebrew package manager, known as Brew, to facilitate software installations and management. On the other hand, CentOS and other Red Hat-based distributions typically uses the YUM (Yellowdog Updater, Modified) or DNF (Dandified YUM) package managers for handling software packages.

For this task, we will use Ubuntu and install Docker. The task further requires installing Jenkins.

Here are the steps to install Docker on Ubuntu:

1. Update the APT package index:

   sudo apt update

2. Install the required packages to allow apt to use a repository over HTTPS:

   sudo apt install apt-transport-https ca-certificates curl software-properties-common

3. Add Docker’s official GPG key:

   curl -fsSLhttps://download.docker.com/linux/ubuntu/gpg| sudo apt-key add -

4. Add the Docker repository to APT sources:

   sudo add-apt-repository "deb [arch=amd64]https://download.docker.com/linux/ubuntu$(lsb_release -cs) stable"

5. Update the APT package index again:

   sudo apt update

6. Install Docker:

   sudo apt install docker-ce

7. Docker should now be installed. You can verify the installation by checking the Docker version:

   docker --version

Usingsystemctl:

systemctl is used to examine and control the state of systemd system and service manager. systemd is system and service manager for Unix like operating systems(most of the distributions, not all).

Now, let's explore using systemctl to manage services like Docker and Jenkins.

Check Docker Service Status:

To check the status of the Docker service, you can use:

systemctl status docker

Stop Jenkins Service:

To stop the Jenkins service, you can use:

sudo systemctl stop jenkins

Comparingsystemctlvsservice:

systemctl is a more powerful and flexible command compared to service. While service is a legacy command that is still available for backward compatibility, systemctl provides more features and integrates better with systemd, which is the default init system in most modern Linux distributions.

For example:

• systemctl status docker provides more detailed information compared to service docker status.

• systemctl can manage not only services but also other systemd units like sockets, targets, timers, and more.

That concludes our journey for Day 7 of the #90DaysOfDevOps challenge. In summary, today we explored the world of package managers and systemctl, essential tools for software management and service control in Linux environments. Stay tuned for more exciting challenges and insights as we continue our DevOps journey together.