Description:
This is a bug on the cloud-init DatasourceVMware side where we convert dhcp ipv6 customization spec to cloud-init networking config, it leaves the ipv6 networking config as blank when it's dhcp ipv6. For ifcfg-rh plugin, it's ok, but for keyfile plugin, it will not set the [ipv6] section in the cloud-init-ens192.nmconnection file.

# cat /etc/NetworkManager/system-connections/cloud-init-ens192.nmconnection
# Generated by cloud-init. Changes will be lost.

[connection]
id=cloud-init ens192
uuid=dfaf916e-1ddf-5437-bf6d-d2dbb171f650
autoconnect-priority=120
type=ethernet

[user]
org.freedesktop.NetworkManager.origin=cloud-init

[ethernet]
mac-address=00:50:56:A5:C7:65

[ipv4]
method=auto
may-fail=false

// Missing [ipv6] section here, it should be method=auto in [ipv6] section.

Test Steps:
1. Deploy VM-template rhel-10 on ESXi
2. Configure VM Customization Specifications - huzhao-dhcp-ipv4v6, which enables both ipv4 and ipv6 as dhcp mode (Please refer to the attachment for the detail config)
3. Clone VM-new from VM-template with Customized file huzhao-dhcp-ipv4v6
4. Check network and NM keyfile

Actual results:
The [ipv6] section is missing in the NM keyfile.

# nmcli -f NAME,FILENAME c show
NAME FILENAME
cloud-init ens192 /etc/NetworkManager/system-connections/cloud-init-ens192.nmconnection
lo /run/NetworkManager/system-connections/lo.nmconnection
ens192 /etc/NetworkManager/system-connections/ens192.nmconnection

# cat /etc/NetworkManager/system-connections/cloud-init-ens192.nmconnection
# Generated by cloud-init. Changes will be lost.

[connection]
id=cloud-init ens192
uuid=dfaf916e-1ddf-5437-bf6d-d2dbb171f650
autoconnect-priority=120
type=ethernet

[user]
org.freedesktop.NetworkManager.origin=cloud-init

[ethernet]
mac-address=00:50:56:A5:C7:65

[ipv4]
method=auto
may-fail=false

// Missing [ipv6] section here, it should be method=auto in [ipv6] section.

# cat /run/cloud-init/network-config.json
{
"config": [
{
"mac_address": "00:50:56:a5:c7:65",
"name": "ens192",
"subnets": [
{
"control": "auto",
"type": "dhcp" // There is only one type dhcp here, there should be both types dhcp4 and dhcp6
}
],
"type": "physical"
}
],
"version": 1
}

Actual results:
There should be both [ipv4] and [ipv6] section in NM keyfile per the customization spec.
e.g.
# cat /etc/NetworkManager/system-connections/cloud-init-ens192.nmconnection
...
[ipv4]
method=auto
...

[ipv6]
method=auto
...

Additional info:
1. When config customization file with cloud-init config data like below, no such issue.
#cloud-metadata
instance-id: cloud-vm-test1
local-hostname: cloud-vm
network:
version: 2
ethernets:
ens192:
match:
name: ens*
dhcp4: yes
dhcp6: yes

# cat /etc/NetworkManager/system-connections/cloud-init-ens192.nmconnection
# Generated by cloud-init. Changes will be lost.

[connection]
id=cloud-init ens192
uuid=dfaf916e-1ddf-5437-bf6d-d2dbb171f650
autoconnect-priority=120
type=ethernet
interface-name=ens192

[user]
org.freedesktop.NetworkManager.origin=cloud-init

[ethernet]

[ipv4]
method=auto

[ipv6]
method=auto

# cat /run/cloud-init/network-config.json
{
"ethernets": {
"ens192": {
"dhcp4": true,
"dhcp6": true,
"match":

}
},
"version": 2
}

2. No such issue on OpenStack/AWS/Azure
3. This issue also exists in rhel-9.5, rhel-9.4, rhel-9.3, rhel-8.10, rhel-8.9