network: ConfigDrive must check Dhcp/Dns on the network, not on itself#132
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network: ConfigDrive must check Dhcp/Dns on the network, not on itself#132msinhore wants to merge 1 commit into
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ConfigDriveNetworkElement.getSupportedServicesByElementForNetwork
gates the population of network_data.json on the ConfigDrive
provider declaring Dhcp and Dns services for the NIC's network. On
any modern offering where ConfigDrive is bound only to UserData and
Dhcp / Dns are delivered by a different provider — Ovn, Netris, Nsx,
even VirtualRouter when the operator has split UserData out — this
predicate returns false. ConfigDriveBuilder.writeNetworkData then
honours the empty service list and writes
`network_data.json = "{}"`.
The ISO ends up with hostname and SSH keys (read from
meta_data.json) but no `links` / `networks` / `services` for
cloud-init. Older cloud-init releases used to fall back to a
DHCP-everything heuristic; cloud-init >= 23 (shipped with Ubuntu
24.04 cloud images and current Debian 12 backports) does not, so
the VM boots with whatever pre-baked netplan is in the image. For
canonical cloud images that means no interface comes up at all,
because their netplan is rendered from datasource at first boot —
which is exactly the path we just defeated.
The Dhcp / Dns checks should not be scoped to the ConfigDrive
element; they should be scoped to the network, because the question
is "does cloud-init need network configuration in the ISO?" not
"does ConfigDrive itself implement Dhcp on this network?". Switch
those two probes to areServicesSupportedInNetwork. UserData stays
scoped to the ConfigDrive provider — that one IS implemented here.
Lab-verified before / after on an OVN-backed isolated network whose
offering is `Dhcp=Ovn / Dns=Ovn / UserData=ConfigDrive`:
Before
/openstack/latest/network_data.json = "{}"
Ubuntu 24.04 cloud image: hostname/SSH keys applied via
cloud-init, no interface up, VM unreachable.
After
/openstack/latest/network_data.json includes links[],
networks[], services[] for the NIC.
Ubuntu 24.04 cloud image: cloud-init renders netplan,
DHCPv4 lease acquired on first boot, VM reachable on its
DHCP-assigned IP.
Affects every CloudStack deployment whose offering routes UserData
to ConfigDrive while routing Dhcp/Dns to a separate provider —
including all OVN-backed offerings, the Netris and NSX route-mode
offerings, and any operator-built offering that decouples the
two. The fix is a one-line predicate change inside core, nothing
provider-specific.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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ConfigDriveNetworkElement.getSupportedServicesByElementForNetwork gates the population of network_data.json on the ConfigDrive provider declaring Dhcp and Dns services for the NIC's network. On any modern offering where ConfigDrive is bound only to UserData and Dhcp / Dns are delivered by a different provider — Ovn, Netris, Nsx, even VirtualRouter when the operator has split UserData out — this predicate returns false. ConfigDriveBuilder.writeNetworkData then honours the empty service list and writes
network_data.json = "{}".The ISO ends up with hostname and SSH keys (read from meta_data.json) but no
links/networks/servicesfor cloud-init. Older cloud-init releases used to fall back to a DHCP-everything heuristic; cloud-init >= 23 (shipped with Ubuntu 24.04 cloud images and current Debian 12 backports) does not, so the VM boots with whatever pre-baked netplan is in the image. For canonical cloud images that means no interface comes up at all, because their netplan is rendered from datasource at first boot — which is exactly the path I just defeated.The Dhcp / Dns checks should not be scoped to the ConfigDrive element; they should be scoped to the network, because the question is "does cloud-init need network configuration in the template?" not "does ConfigDrive itself implement Dhcp on this network?". Switch those two probes to areServicesSupportedInNetwork. UserData stays scoped to the ConfigDrive provider — that one IS implemented here.
Lab-verified before / after on an OVN-backed isolated network whose offering is
Dhcp=Ovn / Dns=Ovn / UserData=ConfigDrive:Before
/openstack/latest/network_data.json = "{}" Ubuntu 24.04 cloud image: hostname/SSH keys applied via cloud-init, no interface up, VM unreachable.
After
/openstack/latest/network_data.json includes links[], networks[], services[] for the NIC. Ubuntu 24.04 cloud image: cloud-init renders netplan, DHCPv4 lease acquired on first boot, VM reachable on its DHCP-assigned IP.
Affects every CloudStack deployment whose offering routes UserData to ConfigDrive while routing Dhcp/Dns to a separate provider — including all OVN-backed offerings, the Netris and NSX route-mode offerings, and any operator-built offering that decouples the two. The fix is a one-line predicate change inside core, nothing provider-specific.