Okay, it’s time to install Git so you can play with some pull and merge requests for some projects you are working on. This set of instructions should work on your system regardless if you are running CentOS 7, 8, or 9.
The first thing to do is elevate…
sudo su
Then update your system.
dnf update
Install Git
dnf install git
Check the installed version
git --version
Just like that, you are ready to “Git” yourself back to coding something grand!
Docker is an operating system virtualization tool that allows us to run applications as containers. In simplest terms, that means you are virtualizing only the application, and not creating an entire virtual machine as you would traditionally do in hypervisors like VMware, Hyper-V, or Nutanix.
Okay, that’s cool… How do we install Docker so we can start to test workloads on it? Well, let me show you how to install Docker on a virtual machine running CentOS 9 Stream. **While I have not tested to confirm, this Docker installation method should be identical on CentOS 8 Stream, as well as for CentOS 7.x
Let us begin by shifting to Sudo mode by running this command first…
sudo su
Then the first thing to do is remove PodMan as it conflicts with Docker.
Let us view what we installed by running these two commands.
rpm -q docker-ce
docker version
Congratulations! You now have Docker installed on your machine.
You’ll probably want to install Docker Compose on your machine too so you can build and run a docker image. You can install it with this simple command.
With CentOS 8 now EOL, it is officially time to upgrade CentOS 8 virtual machines to CentOS 8 Stream. The good news is that it is even quicker and easier than the upgrade from CentOS 7 to CentOS 8 was.
First things first… Take a backup of your virtual machine, or at least a snapshot so that you have something you can revert back to if something goes wrong in this process.
Take a look at what release your CentOS machine is currently running.
cat /etc/centos-release
cat /etc/os-release
As you can see this machine is currently on CentOS 8.5.2111.
At this point, I’m going to enter “sudo su” on my VM and then enter my credentials, so that I can continue as ‘root’ and I don’t have to type “sudo” before every single command.
To begin, start by updating your system.
dnf -y update
The next step is to update your machine to the current CentOS Stream release package.
List and view all of the enabled repositories. You should see they are set to “CentOS Stream 8”.
sudo dnf repolist
Next, synchronize all of the installed packages on your machine.
Note: For situational awareness, this step will upgrade or downgrade packages to match the new CentOS Stream ABI/API and will apparently break 100% RHEL compatibility due to the ABI/API change. This is the perfect example of why you would want to take a full backup of the system before making any changes, just in case the ABI/API change breaks one of your applications running on the system.
dnf -y distro-sync
Reboot your system.
init 6
Confirm that we are now running on CentOS 8 Stream.
cat /etc/centos-release
cat /etc/os-release
We can now see that this machine is now running on CentOS Stream 8.
Warning: CentOS 8 has reached End of Life (EOL) and is no longer supported. You should really consider moving to a supported OS such as CentOS 8 Stream.
I was looking at some virtual machines earlier today and I realized that they were not running the most current version of CentOS. Since I am going to upgrade them, I figured it’d be the perfect time to document the process of how to do it.
The first thing I do is make a backup of my virtual machine. You can’t recover from an accident if you don’t have a recovery point. At the very least, make sure you have taken a snapshot of your virtual machine.
Next, I verify what version of CentOS I’m on by running the following command.
cat /etc/centos-release
From the screenshot below you can see that I am currently on version 7.9.2009.
At this point, I’m going to enter “sudo su” on my VM and then enter my credentials, so that I can continue as ‘root’ and I don’t have to type “sudo” before every single command.
First step is to install the EPEL repository.
yum -y install epel-release
Next, install both ‘yum-utils’ and ‘rpmconf’ by using this command.
yum -y install yum-utils rpmconf
Next, use ‘rpmconf’ to resolve the RPM packages that are in use on your VM.
rpmconf -a
Then clean up any packages that are not required by your system.
CentOS Linux 8 had actually reached the End Of Life (EOL) as of December 31st, 2021. Which means that CentOS 8 will no longer receive development from the official CentOS project. After that EOL date, if you need to update your CentOS (yes, that means us right now), you need to change the mirrors to point to vault.centos.org where they are archived. So a better option would actually be to upgrade to CentOS Stream instead, but we’ll save that for another post… Here is how to change the mirrors.
cd /etc/yum.repos.d/
sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*
dnf update
cd
There are two packages, dracut-network and rpmconf, that conflict with upgradingand need to be removed.
dnf remove dracut-network rpmconf
Remove the old CentOS 7 kernel
rpm -e `rpm -q kernel`
Remove any conflicting packages that are not needed any longer
