Home Assistant OS uses Docker, as does Supervised.
These methods are a collection of containers, managed by the Supervisor container. In the case of Home Assistant OS that includes an operating system (HassOS). You can install either of these inside Docker - Docker in Docker is a Bad Idea 
Then you need a Hypervisor to run Virtual machines to get Home Assistant OS to run. And this PC will run 24/7?
yes, it acts as a server so it’s always on
If you install Home Assistant Supervised you get all the addons etc. Same as if you used HA OS. What you installed was Home Assistant Core which does not.
If you want addons you need to use Supervised or HA OS. Alternately if you use core, you can find appropriate docker containers for whatever functionality you want but these won’t be managed by Home Assistant.
David beat me to it. He is 100% correct. Although keep in mind since you are running Ubuntu, if you install HA Supervised on top of Ubuntu, you will get the dreaded “Unsupported” error message in the logs and on the Supervisor info page. It doesn’t hurt anything, and will run fine, but it will always be there. If you want to avoid seeing that error, install Supervised on top of Debian 10 (replacing Ubuntu on your machine) or install “Home Assistant” (formerly HASSOS) in a virtual environment of your choice on your Ubuntu server.
Terry
Thanks Terry and David. I went over the installation instructions for supervised here and it seems simple to give it a shot without a virtual environment. So I’ll start with that.
Thank 
It is also possible to install HACS (the addon store) in your home assistant core container. If set up correctly, your docker container has persistent storage configured where the config folder is stored.
Locate this folder and follow these steps:
After you restart the container, the addon store (HACS) wil show up and work just as fine as other methods (I’ve been running like this for years).
@Dycell
HACS: Home Assistant Community Store
Similar idea but not the same as the integrated Home Assistant Add-ons
HomeAssistant Supervised/OS users typically use both
HACS components are not addons. They are totally different things and not what the OP was asking about.
it’s a little stupid how this used to be possible with hassio and now they expect you to run an entirely new OS…
This was renamed a year ago to HAOS. Everything that was previouly possible is still possible now. It was just a rename.
As mentioned, most of the addons can be replaced with just a regular docker container from dockerhub. I run HA Core on docker and have yet to find a case where I couldn’t find a regular container for something I needed to integrate. Right now I have Mosquitto, Node Red, MaryTTS and DOODS containers talking to HA.
There probably are some cases but none have impacted me yet. And I also run a lot of isolated containers that I don’t feel the need to integrate with HA.
This is not just a rename. Running HA supervised inn docker on Ubuntu is not supported anymore since then. it’s laughable
HAOS and HA Supervised are two different things, take a read of the installation methods. Hass.io was indeed renamed, you have some catching up to do.
Except they didn’t do that at all, bruh. You can still use Ubuntu and install Container or Core with no issues. You can install HAOS or Supervised in a VM on a Linux OS of your choosing.
Have you still not moved on from your complaining about HA and Ubuntu yet? If not, it’s time. Things change, either move with them or don’t, your call, bruh.
I’m a little late to the party, do you know where these docker containers can be found? Are they able to be created with simple docker run or compose commands? I’ve been searching for a few days now and not been able to find anything that I understand as a way to create the containers unfortunately, so any help would be greatly appreciated!
This has all lost me.
I have just installed, on two SD cards, one version of HA via the pre built Raspberry pi SD image, and theo other via the Docker instructions
I see that Supervisor and the add on store is not installed via Docker, and I can’t afford to jsut go out and buy a new raspberry Pi plus all the bits just to run HA.
So i need to use the Docker method . I treed the other way but ran in to the Python 3.7/3/8/3.9 issue , which again is way beyond my abilities.
So as the original poster of this thread, I need to install and add on-
in my case Air Sonos, as I found the really useful to have.
I have the Raspberry Pi running HomeVision XL Software and the Home Vision X-10 controller device…and want HA running on there.
So, in simple terms ,can i just install some how this add on (AirSonos) to the Docker version …and if so …how ?
Thanks
Add-ons are docker containers specifically designed to work with one of two installation methods:
You appear to be using Home Assistant Container which isn’t designed to support Add-ons. To see a comparison of what each installation method supports, refer to this table in the Installation documentation.
OK, thanks, so can’t be done 
guess I’ll have to keep looking for another solution for my needs
Thanks for letting me know so quickly
Shame that table is not ‘upfront’ in the How to install guides…I have done at least three or four differs installs over the past few days, not spotted tag table before…
I see it now…but not intuitively titled . The title * [Compare Installation Methods] * does not (to me any way) give a clue it tells what each installation method allows to install.
It did not even occur to me that different installation methods, of what appears’ on the outside, to b ether same software, is in fact different packages.
damn…oh well.
What would you suggest its name be to clearly indicate what each installation method provides and how they compare to each other?
Can you elaborate on why you concluded Home Assistant Container is the one you need to use?