feat(opennebula): support ETHx_VLAN_ID for 802.1Q VLAN interfaces

[mcanevet]

Proposed Commit Message

feat(opennebula): support ETHx_VLAN_ID for 802.1Q VLAN interfaces

When ETHx_VLAN_ID is set, context-linux creates a VLAN sub-interface
(e.g. eth0.100) and assigns IP config to it. cloud-init ignored this
variable entirely.

Restructure gen_conf() to check for VLAN_ID per interface: when set,
emit a bare parent entry in ethernets: (MAC match only) and place all
IP configuration in a vlans: entry named <dev>.<id>. The vlans: key
is omitted from the output when no VLANs are configured.

Additional Context

Part of a series bringing cloud-init's OpenNebula datasource to feature
parity with the context-linux package from one-apps.

The Netplan v2 vlans: stanza requires id: (integer) and link: (parent
device name). All other configuration keys (addresses, gateway4, nameservers,
etc.) are placed on the VLAN entry, not the parent.

Test Steps

In an OpenNebula VM context, set:

ETH0_IP="10.0.0.1"
ETH0_MASK="255.255.255.0"
ETH0_VLAN_ID="100"

After boot, verify ip link show includes eth0.100 and ip addr show eth0.100
shows 10.0.0.1/24. The parent eth0 should have no address.

Merge type

• Squash merge using "Proposed Commit Message"
• Rebase and merge unique commits. Requires commit messages per-commit each referencing the pull request number (#<PR_NUM>)

[github-actions]

Hello! Thank you for this proposed change to cloud-init. This pull request is now marked as stale as it has not seen any activity in 14 days. If no activity occurs within the next 7 days, this pull request will automatically close.

If you are waiting for code review and you are seeing this message, apologies! Please reply, tagging blackboxsw, and he will ensure that someone takes a look soon.

(If the pull request is closed and you would like to continue working on it, please do tag blackboxsw to reopen it.)

[mcanevet]

@blackboxsw rebased

[Copilot]

Pull request overview

This PR updates the OpenNebula datasource’s Netplan v2 generation to support OpenNebula’s ETH<x>_VLAN_ID contextualization variable, emitting an 802.1Q VLAN sub-interface (e.g. eth0.100) and applying IP configuration to the VLAN device rather than the parent NIC.

Changes:

• Extend OpenNebulaNetwork.gen_conf() to generate a vlans: section when ETH<x>_VLAN_ID is present, leaving the parent NIC without IP configuration.
• Add unit tests covering VLAN generation, mixed VLAN/non-VLAN NICs, and omission of the vlans key when unused.
• Document ETH<x>_VLAN_ID behavior in the OpenNebula datasource reference docs.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
cloudinit/sources/DataSourceOpenNebula.py	Generate Netplan vlans: stanzas when ETH<x>_VLAN_ID is set and keep the parent NIC unaddressed.
tests/unittests/sources/test_opennebula.py	Add unit tests validating VLAN Netplan output structure and key placement (parent vs VLAN).
doc/rtd/reference/datasources/opennebula.rst	Document the new ETH<x>_VLAN_ID contextualization variable and resulting interface behavior.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.