How I installed 3CX on a VPS without custom ISO support

[pmarks]

I figured out how to boot the 3CX Debian ISO from a cheap VPS that provides a generic Debian ISO, but doesn't let me upload custom ISOs.

First off, I configured the VPS with "Operating System: None - ISO - Self-Installation", because "Debian 10" inserts DHCP options that mess with the 3CX preseeding scripts. This quirk may be specific to my VPS provider. Note that generic Debian prompts you to create a non-root user account, whereas 3CX Debian does not, so that's a good way to check which installer you're running.

Here is the procedure; I'm assuming that you know how to work with Linux and partitions in general:

1. Boot from a generic Debian ISO installer.
2. When you reach the partitioning step, switch to manual mode and create a 512 MB logical partition at the end of the disk, with no filesystem. The partition size should be a bit larger than the 3CX ISO.
3. Go back and let Debian run guided partitioning on the rest of the disk, then proceed with the installation.
4. Log into generic Debian, download the 3CX iso, and clone it onto your special partition. For example:
   

   $ lsblk  # Verify that you're overwriting the correct partition; mine was vda5.
   $ dd if=debian-amd64-netinst-3cx.iso of=/dev/vda5 bs=1M

5. Reboot, press 'c' to drop to a grub2 command line, and launch the 3CX ISO from your special partition:
   

   > set root=(hd0,5)
   > configfile /boot/grub/grub.cfg

6. Ignore the grub errors related to "font" and "splash". The 3CX installer should begin.
7. "Load CD-ROM drivers from removable media?" <No>
8. "Manually select a CD-ROM module and device?" <Yes>, none, /dev/vda5
9. When you reach the partitioning step, delete all partitions except the one with the ISO.
10. Go back and let 3CX Debian run guided partitioning on the rest of the disk, then proceed with the installation.

You should now be running standard 3CX. If you ever want to reinstall, go back to step 5.

 

[YiannisH_3CX]

Thank you for taking the time to share your solution.
For anyone interested here is also the supported installation procedure along with the supported virtual platforms
https://www.3cx.com/docs/manual/installing-debian-linux-pbx/

 

[Alphabetic]

Could you not have let the VPS install Debian 10.

Configured IP settings using Step 4 from this guide:

https://www.3cx.com/docs/installing-pbx-raspberry-pi/

Then install 3CX using these commands:

UNSUPPORTED

Make sure that NTP is installed

apt update
apt install ntp

 

[pmarks]

Could you not [...] install 3CX using these commands

I think my approach is simpler because it doesn't depend on implementation details of the 3CX installer, aside from the location of grub.cfg. I was trying to come up with something that's likely to still work if I need to rebuild a VM in 5 years.