[mythtv-users] mythbackend in a docker container

[Paul Gardiner]

On 05/11/2023 16:09, Mike Perkins wrote:
> I run an (almost) entirely Debian shop. My principle server is a KVM 
> host and runs a number of VMs. My general procedure is to keep two 
> copies of our 'main' server as VMs; I also keep two copies of an http 
> server. One of each is active and the other is either the previous 
> version or the next one, whenever I have to do a release update. (There 
> are other, smaller VMs which are not paired.)
> 
> I can therefore setup and test new versions without disturbing whatever 
> other work is happening. When I am satisfied there are no more gotchas, 
> I copy across the /home directories from the old to the new system 
> followed by a final test.
> 
> Then, in my router, I have domain names registered in the DNS server 
> portion pointing to whichever one is currently active. For example, 
> main.example.com -> 192.168.202.17 and so on. All I need to do is to 
> change the DNS entry and, boom! the new version is in operation.
> 
> Snags: as a VM I have separate LVM logical volumes for system and /home, 
> which makes it slightly easier to adjust volume sizes when required. I 
> do not use copy-on-write (COW) but allocate the whole disk space 
> required. However, KVM treats logical volumes as /disks/ not 
> /partitions/. This does mean an awkward use of 'kpartx' to be able to 
> split out the partitions whenever I want to do a copy. (There are 
> probably easier methods.)
> 
> Obviously most of the above has to be done from either the console or an 
> ssh session into the host server. Once I have a new system disk I can, 
> however, use the hostname to connect to it for testing. I use thin(nish) 
> clients with x2go for normal work, the only thing that cannot be done 
> via x2go is mythtv playback. I have, however, used Firefox to access 
> CCTV and they play back fine over that arrangement.

These discussions have made me realise that I probably don't actually 
need to run mythbackend with capture cards under a VM. My testing at the 
moment of a freshly installed server is of mythbackend running without 
capture cards because the capture cards are in the still running 
production server. It's only at the very last stage of the server swap 
that I move hardware from one server to the other and make the final 
test. It would be a big win for me if I could just perform the install 
in a VM, so that I avoid the need for two servers and avoid moving 
hardware. Clearly that's possible and, from what you've said, usually 
problem free.

Do you know if, with KVM, I can assign a disc to a VM, perform an 
install and then update grub so that the machine boots directly into 
that disc without KVM involved? I guess it has to be possible - it's 
just whether it's easy or hellish.

Paul.