For anyone with this issue in 2023 and beyond, the user is now “fogproject”
So the final command should be:

chown -R fogproject:root /images

SOLUTION: If you are running in a Proxmox container, you need to a.) uncheck ‘Unprivileged’ during creation and, b.) edit the container after creation and enable both Nesting and NFS (Container > Options > Features > Edit).
Solution found here: https://forums.fogproject.org/topic/15176/fog-server-in-lxc-container-under-proxmox-6?_=1640279743123

(Is there no way to mark original post as solved?)

Ubuntu 20.04 Proxmox container template
FOG 1.5.9.114 dev branch
New install

You guessed it, Proxmox container. I originally tried to install FOG on baremetal, but I am using the server for more than just FOG and the install script doesn’t like multiple IP addresses on one interface. Running FOG in a container was my solution to that as the container only sees the virtual NIC.

Is there a workaround for running in a container or is this not supported?

Re: Unit nfs.service could not be found

This is likely an issue outside of the FOG project, but as there was no solution or workaround in the original thread I’m hoping to uncover what is going on here.

The package nfs-kernel-server is installed as part of installfog.sh, however just like in the linked thread, nfs.service cannot be found and the install script fails. I confirmed that nfs-kernel-server was included in the packages downloaded by the script, and even with a manual install/update (Linux says I have the latest version) the file cannot be found.

I will keep searching for a solution outside FOG and update here if I find anything.

EDIT: Here is the output of journalctl. Despite the ‘permission denied’ error I am running the script as root as instructed:

-- A start job for unit nfs-config.service has begun execution.
--
-- The job identifier is 485.
Dec 22 02:11:59 fogserver mount[1639]: mount: /proc/fs/nfsd: permission denied.
Dec 22 02:11:59 fogserver systemd[1]: proc-fs-nfsd.mount: Mount process exited, code=exited, status=32/n/a
-- Subject: Unit process exited
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- An n/a= process belonging to unit proc-fs-nfsd.mount has exited.
--
-- The process' exit code is 'exited' and its exit status is 32.
Dec 22 02:11:59 fogserver systemd[1]: proc-fs-nfsd.mount: Failed with result 'exit-code'.
-- Subject: Unit failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- The unit proc-fs-nfsd.mount has entered the 'failed' state with result 'exit-code'.
Dec 22 02:11:59 fogserver systemd[1]: Failed to mount NFSD configuration filesystem.
-- Subject: A start job for unit proc-fs-nfsd.mount has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit proc-fs-nfsd.mount has finished with a failure.
--
-- The job identifier is 481 and the job result is failed.
Dec 22 02:11:59 fogserver systemd[1]: Dependency failed for NFS server and services.
-- Subject: A start job for unit nfs-server.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit nfs-server.service has finished with a failure.
--
-- The job identifier is 478 and the job result is dependency.
Dec 22 02:11:59 fogserver systemd[1]: Dependency failed for NFS Mount Daemon.
-- Subject: A start job for unit nfs-mountd.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit nfs-mountd.service has finished with a failure.
--
-- The job identifier is 484 and the job result is dependency.
Dec 22 02:11:59 fogserver systemd[1]: nfs-mountd.service: Job nfs-mountd.service/start failed with result 'dependency'.
Dec 22 02:11:59 fogserver systemd[1]: Dependency failed for NFSv4 ID-name mapping service.
-- Subject: A start job for unit nfs-idmapd.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit nfs-idmapd.service has finished with a failure.
--
-- The job identifier is 492 and the job result is dependency.
Dec 22 02:11:59 fogserver systemd[1]: nfs-idmapd.service: Job nfs-idmapd.service/start failed with result 'dependency'.
Dec 22 02:11:59 fogserver systemd[1]: nfs-server.service: Job nfs-server.service/start failed with result 'dependency'.
Dec 22 02:11:59 fogserver mount[1640]: mount: /run/rpc_pipefs: permission denied.
Dec 22 02:11:59 fogserver systemd[1]: run-rpc_pipefs.mount: Mount process exited, code=exited, status=32/n/a
-- Subject: Unit process exited
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- An n/a= process belonging to unit run-rpc_pipefs.mount has exited.
--
-- The process' exit code is 'exited' and its exit status is 32.
Dec 22 02:11:59 fogserver systemd[1]: run-rpc_pipefs.mount: Failed with result 'exit-code'.
-- Subject: Unit failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- The unit run-rpc_pipefs.mount has entered the 'failed' state with result 'exit-code'.
Dec 22 02:11:59 fogserver systemd[1]: Failed to mount RPC Pipe File System.
-- Subject: A start job for unit run-rpc_pipefs.mount has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit run-rpc_pipefs.mount has finished with a failure.
--
-- The job identifier is 488 and the job result is failed.
Dec 22 02:11:59 fogserver systemd[1]: Dependency failed for RPC security service for NFS client and server.
-- Subject: A start job for unit rpc-gssd.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit rpc-gssd.service has finished with a failure.
--
-- The job identifier is 490 and the job result is dependency.
Dec 22 02:11:59 fogserver systemd[1]: rpc-gssd.service: Job rpc-gssd.service/start failed with result 'dependency'.
Dec 22 02:11:59 fogserver systemd[1]: Dependency failed for RPC security service for NFS server.
-- Subject: A start job for unit rpc-svcgssd.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit rpc-svcgssd.service has finished with a failure.
--
-- The job identifier is 487 and the job result is dependency.
Dec 22 02:11:59 fogserver systemd[1]: rpc-svcgssd.service: Job rpc-svcgssd.service/start failed with result 'dependency'.
Dec 22 02:11:59 fogserver systemd[1]: nfs-config.service: Succeeded.
-- Subject: Unit succeeded
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- The unit nfs-config.service has successfully entered the 'dead' state.
Dec 22 02:11:59 fogserver systemd[1]: Finished Preprocess NFS configuration.
-- Subject: A start job for unit nfs-config.service has finished successfully
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit nfs-config.service has finished successfully.
--
-- The job identifier is 485.