📖 proposal: add support for defining trunk subports #2862

bnallapeta · 2025-11-26T09:12:41Z

What this PR does / why we need it:
Proposal doc for #2861

/hold

Signed-off-by: Bharath Nallapeta <nr.bharath97@gmail.com>

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k8s-ci-robot · 2025-11-26T09:12:49Z

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bnallapeta · 2025-11-26T09:14:58Z

/cc @lentzi90

bnallapeta · 2025-12-04T10:10:20Z

@lentzi90 do you have some time to take a look at this?

smoshiur1237

Some comments regarding formatting of md files. I was getting the following minor issues in the docs . It will improve the md file formatting .

smoshiur1237 · 2025-12-16T11:24:02Z

docs/proposals/20251126-trunk-subports.md

+- Maintain backward compatibility with existing port configurations
+- Follow OpenStack Networking (Neutron) trunk API patterns
+
+### Non-Goals


Need one empty line after the title

smoshiur1237 · 2025-12-16T11:24:15Z

docs/proposals/20251126-trunk-subports.md

+
+## Motivation
+
+### Goals


Need one empty line after the title

smoshiur1237 · 2025-12-16T11:24:52Z

docs/proposals/20251126-trunk-subports.md

+
+### User Stories
+
+#### Story 1: NFV Workloads


Need one empty line after the title

smoshiur1237 · 2025-12-16T11:25:01Z

docs/proposals/20251126-trunk-subports.md

+#### Story 1: NFV Workloads
+As a user deploying Network Function Virtualization (NFV) workloads, I need to attach my VM to multiple VLANs through a single trunk interface to separate control plane and data plane traffic without consuming multiple physical interfaces or PCI slots.
+
+#### Story 2: Multi-Tenant Networking


Need one empty line after the title

smoshiur1237 · 2025-12-16T11:26:07Z

docs/proposals/20251126-trunk-subports.md

+```go
+type PortOpts struct {
+    // ... existing fields ...
+


remove the empty line

smoshiur1237 · 2025-12-16T11:27:24Z

docs/proposals/20251126-trunk-subports.md

+1.  **`EnsureTrunkSubPorts` Method**:
+    - Iterates through the desired ports.
+    - If `trunk: true` is set, it checks for `Subports`.
+    - For each subport:
+        - Creates a regular Neutron port using `CommonPortOpts`.
+        - Adds the port as a subport to the parent trunk using the `AddSubports` API, specifying the `SegmentationID` and `SegmentationType`.


I think you have used space 4. please use space 2

So far we have not used so strict formatting in CAPO. I think we need to discuss this first and agree on a style. Maybe also go through older docs and reformat them so we can actually enforce the style. Otherwise it will just be inconsistent.

smoshiur1237 · 2025-12-16T11:28:53Z

docs/proposals/20251126-trunk-subports.md

+- **Manual Configuration**: Users could manually create trunks and subports using the OpenStack CLI and reference them by ID.
+    - *Pros*: No code changes in CAPO.
+    - *Cons*: Breaks the "Infrastructure as Code" model; manual steps are error-prone and hard to automate in CAPI workflows.
+- **Separate CRD**: Introduce a new CRD for Trunks/Subports.
+    - *Pros*: Decouples networking from Machine.
+    - *Cons*: Increases API surface area and complexity for common use cases. Embedding in `OpenStackMachine` is more ergonomic for the 90% case.


Please confirm with space 2. In my editor it is showing space 4

lentzi90

Sorry for the delay!
I don't have any immediate concerns. It looks like a useful feature.
However, I think we should coordinate this with ORC so we don't end up making things unnecessarily painful later.
There is already a Port resource in ORC, but I don't think it has Trunk support yet.

@mandre could you check this? Do you see any issues with this if we later want to adopt ORC Ports? Would it be better to go for a separate CRD (perhaps implemented in ORC)?

/cc @mandre

lentzi90 · 2025-12-18T07:30:06Z

docs/proposals/20251126-trunk-subports.md

+1.  **`EnsureTrunkSubPorts` Method**:
+    - Iterates through the desired ports.
+    - If `trunk: true` is set, it checks for `Subports`.
+    - For each subport:
+        - Creates a regular Neutron port using `CommonPortOpts`.
+        - Adds the port as a subport to the parent trunk using the `AddSubports` API, specifying the `SegmentationID` and `SegmentationType`.


So far we have not used so strict formatting in CAPO. I think we need to discuss this first and agree on a style. Maybe also go through older docs and reformat them so we can actually enforce the style. Otherwise it will just be inconsistent.

lentzi90 · 2025-12-18T07:32:05Z

docs/proposals/20251126-trunk-subports.md

+
+2.  **Lifecycle Management**:
+    - Subports are created after the parent port and trunk are created.
+    - Deletion of the `OpenStackMachine` will naturally clean up the ports, but explicit cleanup logic for trunks and subports ensures no orphaned resources.


This is unclear to me. Do we need to clean up or will it happen automatically? If it happens automatically, why would manual cleaning ensure no orphaned resources? Wouldn't that be ensured anyway?

winiciusallan · 2025-12-18T13:41:05Z

Sorry for the delay! I don't have any immediate concerns. It looks like a useful feature. However, I think we should coordinate this with ORC so we don't end up making things unnecessarily painful later. There is already a Port resource in ORC, but I don't think it has Trunk support yet.

Hi @lentzi90! ORC already has a work still in progress to add a new Trunk controller on this PR. Since it is still in progress, I believe it can be aligned with CAPO interests.

(sorry for meddling)

bnallapeta · 2025-12-23T06:38:55Z

@winiciusallan Thanks for the info. I checked out the current ongoing work on Trunk controller. While it implements the feature I have proposed here, the approach is totally different, but I guess that's a bigger question about the design itself (multiple, individual custom resources (Port, Trunk, Machine)).

@lentzi90 @mandre I see two paths moving forward here.

We wait for the work to be completed in ORC and plan for migrating it to CAPO. Although, that isn't just about this feature but rather about the entire networking feature. That's gonna be a big one.
I could do this feature right now in CAPO, but I don't want it to be a wasted effort in a couple months or so since we plan to migrate to ORC anyways. In that case, the whole approach changes and this proposal would not make much sense.

Thoughts? I am inclined towards letting this go at this point and plan for the bigger migration work. Please let me know.

lentzi90 · 2025-12-23T06:43:00Z

The first option sounds good to me, as long as you can wait for it.
I'll try to get some time early next year to help with the planning for how to migrate to use more of ORC 🤞

proposal: add support for defining trunk subports

83fc91f

Signed-off-by: Bharath Nallapeta <nr.bharath97@gmail.com>

github-project-automation bot moved this to Inbox in CAPO Roadmap Nov 26, 2025

github-project-automation bot added this to CAPO Roadmap Nov 26, 2025

k8s-ci-robot added the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Nov 26, 2025

k8s-ci-robot requested review from EmilienM and smoshiur1237 November 26, 2025 09:12

k8s-ci-robot added size/L Denotes a PR that changes 100-499 lines, ignoring generated files. cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. labels Nov 26, 2025

k8s-ci-robot requested a review from lentzi90 November 26, 2025 09:15

smoshiur1237 reviewed Dec 16, 2025

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lentzi90 reviewed Dec 18, 2025

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k8s-ci-robot requested a review from mandre December 18, 2025 07:39

bnallapeta closed this Jan 5, 2026

github-project-automation bot moved this from Inbox to Done in CAPO Roadmap Jan 5, 2026

bnallapeta mentioned this pull request Jan 5, 2026

Add trunk subports support for OpenStackMachine ports #2861

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📖 proposal: add support for defining trunk subports #2862

📖 proposal: add support for defining trunk subports #2862

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