Cloud-Init for RHEL/CentOS/Rocky on Proxmox

I have noticed that when provisioning RHEL-based templates, the hostname is always set to localhost. However, there is a workaround that allows cloud-init to set the hostname in the OS as it is in Proxmox.

Note: This solution may also work with other platforms that use cloud-init, such as VMware and OpenStack.

How to Fix the Problem

To resolve this issue, follow the steps below:

Step 1: Download the Cloud Image

Download the cloud image for RHEL/CentOS/RockyLinux. In this guide, we will use RockyLinux.

Image: Rocky-9-GenericCloud-Base-9.2-20230513.0.x86_64.qcow2 URL: Download RockyLinux Cloud Image

Step 2: Enable NBD on the Proxmox Host

Start by enabling the Network Block Device (NBD) on the Proxmox host. Run the following command:

modprobe nbd max_part=8

Step 3: Connect the QCOW2 as a Network Block Device

Connect the downloaded QCOW2 file as a network block device (NBD) using the following command:

qemu-nbd --connect=/dev/nbd0 Rocky-9-GenericCloud-Base-9.2-20230513.0.x86_64.qcow2

Step 4: Find the Virtual Machine Partitions

Use the following command to identify the virtual machine partitions:

fdisk /dev/nbd0 -l

Make a note of the partition, e.g., /dev/nbd0p5.

Step 5: Mount the VM Partition

Mount the virtual machine partition using the following command:

mount /dev/nbd0p5 /mnt/somepoint/

Step 6: Edit /etc/cloud/cfg

Open the /etc/cloud/cfg file and add the following line:

prefer_fqdn_over_hostname: false

The updated file should look like this:

  
---
# This will cause the set+update hostname module to not operate (if true)
preserve_hostname: false
prefer_fqdn_over_hostname: false
---

Step 7: Unmount and Disconnect

After making the necessary changes, unmount the partition and disconnect from the network block device:

umount /mnt/somepoint/
qemu-nbd --disconnect /dev/nbd0
rmmod nbd

Step 8: Create a New Virtual Machine

Create a new virtual machine with the following command:

  
qm create 8000 --memory 2048 --core 2 --name rocky-9-cloud --net0 virtio,bridge=vmbr0

Step 9: Import the Modified RockyLinux Disk

Import the modified RockyLinux disk into the local-lvm storage:

qm importdisk 8000 Rocky-9-GenericCloud-Base-9.2-20230513.0.x86_64.qcow2 local-lvm

Step 10: Attach the New Disk to the VM

Attach the new disk to the virtual machine as a SCSI drive on the SCSI controller:

  
qm set 8000 --scsihw virtio-scsi-pci --scsi0 local-lvm:vm-8000-disk-0

Step 11: Add Cloud-Init Drive

Add the cloud-init drive to the virtual machine:

qm set 8000 --ide2 local-lvm:cloudinit

Step 12: Make the Cloud-Init Drive Bootable

Make the cloud-init drive bootable and restrict the BIOS to boot from the disk only:

  
qm set 8000 --boot c --bootdisk scsi0

Step 13: Add Serial Console

Add a serial console to the virtual machine:

  
qm set 8000 --serial0 socket --vga serial0

Step 14: Create Template

Create a template for the virtual machine:

qm template 8000

Goodbye, localhost!

After following these steps, your virtual machine’s hostname should match the one you set in Proxmox. Note that you may need to set the CPU type to “Host” for the image to boot. For more information, refer to this RHEL 9.0 Proxmox installation troubleshooting thread.

References: