This video is about container runtimes.
The container runtime is the software that runs a container.
And common container runtimes are ContainerD and Cryo.
You write C-R-I-O, but Cryo is the way to pronounce it.
The container runtime is a part of the container engine.
And the container engine is a complete software solution that is used to start
and manage the container.
Docker and Popman are the most common container engines.
There are some small other ones around as well.
Docker started the container revolution in the year 2013-2014.
And Docker has been the dominant container engine until the release of
Red Hat Enterprise Linux 8 in 2018.
And that is because Red Hat didn't want to be depending on the Docker development.
Red Hat wanted something themselves.
And that is why with the release of RHEL 8,
Red Hat offered Popman as a replacement for Docker.
And it dropped support for Docker.
And in case you are wondering,
wasn't that problematic for current Red Hat Docker users?
No, because container images are standardized in the Open Containers Initiative.
And if you just replace Docker with Popman, it would work.
Also, because Popman is using a CLI experience that's completely similar to the Docker CLI,
Popman is now commonly available and used in all the distributions as an alternative for Docker.
Now, let me tell you how you can use Docker on Ubuntu.
If you want to use Docker on Ubuntu, you need to install it.
That's pretty easy.
Just use sudo apt install docker.io.
Popman on Red Hat does not need any further installation,
because it's part of the default installation of most Red Hat and Red Hat family installation patterns.
Only on minimal installations, you may have to use dnf install popman to get your hands on it.
Let me show you how to install Docker on Ubuntu.
So how do we install Docker?
Well, simple, sudo apt install docker.io.
And that should be doing it.
So how about a first test drive Docker run nginx?
Oh no, permission denied.
You know what is going on?
In order to run Docker, the user who wants to run Docker needs to be a member of the Docker group.
So I'm going to use sudo usermod minus a uppercase G docker for student, which is my local account.
Next, the problematic thing is that I would need to log out and log in again.
But that's a little trick when I use new grp docker and I use id again.
Now you can see that I'm a member of the group Docker.
And as a result, I should be able to use Docker run minus d nginx.
Minus d is running it in detached mode.
And there we can see that I'm running it in detached mode.
Minus d is running it in detached mode.
And there we can see that it is unable to find the image locally.
It is running the image and it just did.
So we have Docker up and running.
Oh, and don't try to install Docker on Red Hat and family.
Because on Red Hat and family, it's really not supported.
And it will break with every single software update you do.
On Red Hat and family, Podman is the alternative.
And the good news is that Podman has the exact same command line experience as Docker.
All the arguments are the same.
So instead of Docker run minus d nginx, you would use Podman run minus d nginx.
More about this in the next couple of videos.