I run a small server with Proxmox, and I’m wondering what are your opinions on running Docker in separate LXC containers vs. running a specific VM for all Docker containers?
I started with LXC containers because I was more familiar with installing services the classic Linux way. I later added a VM specifically for running Docker containers. I’m thinking if I should continue this strategy and just add some more resources to the docker VM.
On one hand, backups seem to be easier with individual LXCs (I’ve had situations where I tried to update a Docker container but the new container broke the existing configuration and found it easiest just to restore the entire VM from backup). On the otherhand, it seems like more overhead to install Docker in each individual LXC.
Regardless of VM or LXC, I would only install docker once. There’s generally no need to create multiple docker VMs/LXCs on the same host. Unless you have a specific reason; like isolating outside traffic by creating a docker setup for only public services.
Backups are the same with VM or LXC on Proxmox.
The main advantages of LXC that I can think of:
- Slightly less resource overhead, but not much (debian minimal or alpine VM is pretty lightweight already).
- Ability to pass-through directories from the host.
- Ability to pass-through hardware acceleration from a GPU, without passing through the entire GPU.
- Ability to change CPU cores or RAM while it’s running.
Also LXC shares the host filesystem to there is less concern with corruption due to power loss.
I use individual lxc for each docker compose so I don’t have to revert 8 services at once if I need to restore.
I would also argue that an alpine lxc runs in 22mb ram by itself … Significantly smaller footprint on disk and in memory. But most importantly, lxc can actually share memory space effectively, one doesn’t need to reserve blocks of ram.
How do you handle backups? Install restic or whatever in every container and set it up? What about updates for the OS and docker images, watchtower on them I imagine?
It sounds like a ton of admin overhead for no real benefit to me.
I just snapshot the parent lxc. The data itself isn’t part of the container at any level, so if I bung up compose yml or env, I can just flip it back. The only real benefit is that all my backups are in the same place in the same format.
Like I’m not actually opposed to managing docker in one unit, I just haven’t got there yet and this has worked so far.
If I were to move to a single platform for several docker, what would you suggest? For admin and backups?
What’s the purpose of running container in a container? Why not install docker on your host machine?
You want to to keep modification of the host to a minimum in virtualization. It makes troubleshooting so much easier.
Dockers ‘take-over-system’ style of network management will interfere with proxmox networking.
If you do that, Docker is stuck on that host. If it’s in an LXC it can move to another host. Plus, backing up and snapshotting are easier IMO.
