Running Free Load Balancer on Proxmox (or Preventing a Kemp LoadMaster Boot-loop)

Proxmox VE (Virtual Environment) is a “complete open-source platform for enterprise virtualization”. In other words, it’s a toolbox for launching and managing virtual machines (“VM”). While I’ve played around with a handful of virtualization solutions (Microsoft Hyper-V, VMware ESXi, XCP-ng, to name a few), Proxmox became my go-to platform due to both being open source and very beginner friendly.

The other day, I required a Load Balancer for some testing, so I decided on using Kemp Virtual LoadMaster (VLM), a free virtual solution (with some limitations). I ran into a boot-loop issue, so below are the basic instructions for deploying Kemp LoadMaster on Proxmox successfully.

Getting Started

First, this “guide” is based on the assumption you already have a working Proxmox environment. If you don’t, many bare metal server providers have deployment templates that include Proxmox. If not, hit up the Proxmox Wiki. My environment is running Proxmox v6.1-5.

You will need to grab a copy of LoadMaster from https://freeloadbalancer.com/download/, if you haven’t already. It does require a (free) account to access.

Although the platform dropdown does include a KVM/Xen option (Proxmox runs KVM), Proxmox provides great support for migrating from ESXi/vSphere, so I recommend grabbing the VMware image (Direct Link). There’s no difference in functionality, just how it’s packaged.

Deployment

Next, unpack the downloaded zip file containing the LoadMaster VM image. The simplest tool is unzip. The image is in a zip file within the zip file (zip-inception!), so be sure to unpack that packaged zip as well. The result will be a handful of files, including some pdf manuals, but the files we are interested in are the ovf (the “template”) and the vmdk (the “image”).

The Proxmox toolbox includes a method for deploying VMware templates, aptly called importovf. Perform the following command, where “[ID]” is your next available ID, “[VERSION] is the version of LoadMaster, and “[SERVER]” is your deployment instance.

qm importovf [ID] LoadMaster-VLM-[VERSION].RELEASE-VMware-VBox-OVF-FREE.ovf [SERVER]

If you login to the web interface (or run qm list) you should now see the “LoadMasterVLM” machine.

Modifying the Config

If you boot the “LoadMasterVLM” machine as-is, it will start and get you to the login screen. After a few seconds, it will error and reboot.

lb100 login: grep: /.mnt/syslinux.cfg: No such file or directory
Cannot open kernel
Virtual Machine has been killed
/sbin/init.d/rc2.d/S99final: line 71: /.mnt/.VERSION: No such file or directory
Magic key:
Machine is being taken down 

The solution is really quite simple.

On the web interface, head to the “Hardware” tab of the “LoadMasterLVM” VM. For the SCSI Controller, change change it from the Default (normally LSI 53C895A) to VMware PVSCSI. If you are modifying the VM config file directly from the terminal (/etc/pve/qemu-server/[ID].conf), the value would be scsihw: pvscsi.

While you are on the Hardware page, it’s probably a good idea to add a Network Adapter. After these changes are made, the end product should look similar to the below.

Closing Thoughts

There you have it. Simply changing the default SCSI controller to VMware PVSCSI is all it takes to get Kemp’s Virtual LoadMaster (VLM) booting and past the “grep: /.mnt/syslinux.cfg: No such file or directory” error.

While the free version of Kemp’s LoadMaster does limit the bandwidth to 20mbps, it’s quite sufficient for a lab environment. If you need something without the limitations and can’t afford (or don’t need) the LoadMaster Commercial version, or if you would just prefer to go with an open-source solution, HAProxy would be the tool of choice.