Proxmox: Run Docker on Linux Containers (LXC)

In this post, I show you how to run Docker in your Linux Containers (LXC), allowing you to save on resource requirements typically required by a VM.
Proxmox: Run Docker on Linux Containers (LXC)
In: Proxmox, Home Lab

Why Docker on a Linux Container?

Simply put – saving resources. Proxmox official support would always recommend that you run Docker in VMs, but the disadvantage to that is that VMs require more resources from the hypervisor. Running Docker in a Linux Container (LXC) will allow you to run Docker at a fraction of the resource requirements with much faster boot speeds.

Any time you want to run Docker on a Linux Container, simply repeat the steps as documented here.
Using ZFS?

These steps were tested on a Proxmox node configured with ZFS and no observable issues could be detected.

Preparing Proxmox

Ensure FUSE OverlayFS is Installed on the Hypervisor

fuse-overlayfs is really only required if your Proxmox node's storage backend is ZFS, as my research indicates that this is a requirement for keeping Docker volume sizes from blowing up
apt clean && apt update
apt install -y fuse-overlayfs

Create a Linux Container and Test Functionality

Create the Linux Container

Right click your node and click 'Create CT'
Ensure the container is unprivileged and nesting is enabled
Choose your container template
Add a disk, size according to your needs
Allocate cores according to your needs
Allocate RAM according to your needs
Set your NIC parameters according to your environment
I am using my internal domain and DNS server for this VLAN
Click finish to create the container

Change a Few Container Options

Click on your container
Click 'Options'
Double-click 'Features'
As mentioned earlier, you only need to enable FUSE if your Proxmox storage backend is ZFS
Enable 'keyctl', 'Nesting', and 'FUSE'

You may now start the container.

Configure and Test Docker

Install and Configure FUSE OverlayFS on the Linux Container

Repeating here, once again, that you only require fuse-overlayfs if your Proxmox node storage backend if ZFS
apt clean && apt update
apt install -y fuse-overlayfs
ln -s /usr/bin/fuse-overlayfs /usr/local/bin/fuse-overlayfs

Install Docker Engine on the Linux Container

Since the image I am using is Debian 11, we can follow the official Docker Engine installation instructions for Debian.

Install Docker Engine on Debian
Instructions for installing Docker Engine on Debian
# Ensure pre-requisites are installed
apt install -y ca-certificates curl gnupg lsb-release

# Add Docker GPG key
mkdir -p /etc/apt/keyrings
curl -fsSL | gpg --dearmor -o /etc/apt/keyrings/docker.gpg

# Add Docker apt repository
echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] $(lsb_release -cs) stable" | tee /etc/apt/sources.list.d/docker.list > /dev/null

# Update sources and install Docker Engine
apt update
apt install -y docker-ce docker-ce-cli docker-compose docker-compose-plugin

# Test for successful installation
docker run hello-world

# Enable the Docker engine to start at boot
systemctl enable docker


Docker LXC Unprivileged container on Proxmox 7 with ZFS
I’m using Proxmox 7.0-11 on ZFS filesystem and I’m trying to use Dokku (which uses Docker) on a Ubuntu 20.04 LXC Unprivileged container. On the container, I enabled the nesting and keyctl features right after created using the Ubuntu 20.04 template. Here the config: root@srv001:~# pct config…
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