Linux Containers (LXC) is a great way to increase the density of your Proxmox server. The runtime costs for containers are low, usually negligible. However, there are some drawbacks that need to be considered:

Proxmox VE uses Linux Containers (LXC) as its underlying container technology and it has low, usually negligible running expenses. However, there are some drawbacks to consider:

• Proxmox Containers can Linux distributions. Other operating systems, such as FreeBSD or Microsoft Windows, cannot be used in a container environment. See Supported Distributions
• Containers must be restricted in order to safeguard the resources available on the host. As a result, containers operate in their own namespaces. Within containers, several syscalls (userspace requests to the Linux kernel) are prohibited.

Container nesting

I use containers for testing and homelab usage. This is possible to run those containers on LXC Containers with nesting support - a much more efficient option than running full VMs. Settings this up is fairly straightforward, and for quick provisioning you can set this up as a Container Template, running your favorite Linux distribution with the container runtime tools pre-installed

Enable nesting features in the Proxmox VE Container Configuration

1. Make sure the Container is shutdown

2. Locate and edit the Proxmox VE Container Configuration, /etc/pve/lxc/<CTID>.conf file, which stores container configuration - where CTID is the numeric ID of the given container.

   # On the proxmox host server
   # e.g. where my LXC ID is 101  
   
    nano /etc/pve/lxc/101.conf  
   

3. Insert at the bottom of the file:

   features: keyctl=1,nesting=1  
   

4. Start the LXC Instance

5. Install Container runtime tools, for example, Docker

   sudo apt-get update  
    sudo apt-get remove docker docker-engine docker.io containerd runc  
    sudo apt-get -y install apt-transport-https ca-certificates curl gnupg  
    lsb-release  
   
    curl -fsSL https://download.docker.com/linux/debian/gpg | sudo gpg --dearmor
    -o /usr/share/keyrings/docker-archive-keyring.gpg  
   
    echo  
    "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg\]
    https://download.docker.com/linux/debian  
    $(lsb\_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list >
    /dev/null  
   
    sudo apt-get update  
    sudo apt-get install -y docker-ce docker-ce-cli containerd.io docker-compose  
   	
    #̲# Start Docker sudo systemctl enable docker  
   

6. Confirm you can run a docker container:

   docker run hello-world