Add weighted address strategy for multi-key listeners (#2394) by gabordozsa · Pull Request #2405 · skupperproject/skupper

gabordozsa · 2026-03-13T20:35:35Z

Add weighted address strategy for multi-key listeners

…#2394) Signed-off-by: Gabor Dozsa <gabor.dozsa@ibm.com>

pwright · 2026-03-18T14:26:34Z

config/crd/bases/skupper_multikeylistener_crd.yaml

+                      WeightedStrategySpec specifies a map of routing keys to route traffic to.
+                      Each routingKey has a weight value.
+
+                      With this strategy traffic is distributed randomly among the reachable


Consider following rewrite:

The listener distributes traffic among reachable routing keys according to their weights. Routing keys with higher weights receive a larger portion of the traffic. If all keys are assigned the same weight, traffic is split equally between them.

Changed the comment as suggested.

pwright · 2026-03-18T14:29:26Z

config/crd/bases/skupper_multikeylistener_crd.yaml

                    type: object
+                  weighted:
+                    description: |-
+                      WeightedStrategySpec specifies a map of routing keys to route traffic to.


Suggested change

WeightedStrategySpec specifies a map of routing keys to route traffic to.

WeightedStrategySpec defines a mapping of routing keys to weights.

Changed as suggested.

pwright · 2026-03-18T14:30:57Z

config/crd/bases/skupper_multikeylistener_crd.yaml

+                  weighted:
+                    description: |-
+                      WeightedStrategySpec specifies a map of routing keys to route traffic to.
+                      Each routingKey has a weight value.


not necessary if prev comment accepted.

pwright · 2026-03-18T14:31:52Z

config/crd/bases/skupper_multikeylistener_crd.yaml

+                        additionalProperties:
+                          type: integer
+                        description: |-
+                          routingKeysReachable is a map of routingKeys with at least one


Suggested change

routingKeysReachable is a map of routingKeys with at least one

routingKeysReachable is a mapping of routingKeys to weights with at least one

Changed as suggested.

pwright · 2026-03-18T14:33:32Z

pkg/apis/skupper/v2alpha1/multikeylistener_types.go

 	RoutingKeys []string `json:"routingKeys"`
 }

+// WeightedStrategySpec specifies a map of routing keys to route traffic to.


depending on comments above, might need to change these comments

All previous comments are generated from this file. I made the changes in this file and generated the yaml again.

fgiorgetti

It is working great on both kubernetes with system sites. Nice job @gabordozsa.

One thing that we need to consider, is whether the strategy field should be immutable or not. If we allow it to change, we should cleanup the status.strategy field and update it with the new strategy.

internal/nonkube/common/site_state_validator.go

fgiorgetti · 2026-03-19T13:30:52Z

internal/nonkube/common/site_state_validator.go

+					return fmt.Errorf("invalid multikeylistener: %s - routingKey must not be empty", mkl.Name)
+				}
+				if weight <= 0 {
+					return fmt.Errorf("invalid multikeylistener: %s - weight value must not be positive", mkl.Name)


must be positive (remove the not).

fgiorgetti · 2026-03-19T13:42:21Z

pkg/apis/skupper/v2alpha1/multikeylistener_types.go

-		return true
+
+	if m.Spec.Strategy.Priority != nil {
+		if m.Status.Strategy.Priority == nil {


Should it force Status.Strategy.Weighted = nil (and the opposite when using Weighted) to clean up old status in case the strategy has changed?

gabordozsa · 2026-03-20T09:27:10Z

One thing that we need to consider, is whether the strategy field should be immutable or not. If we allow it to change, we should cleanup the status.strategy field and update it with the new strategy.

@fgiorgetti I think the strategy field should be immutable for now. The router does not allow updating the strategy so, the control plane should delete and re-create the multi-key listener if strategy changes. That would terminate existing TCP connections. If strategy update is required, we may add it in a follow up change including the router support for it.

fgiorgetti · 2026-03-20T13:20:32Z

One thing that we need to consider, is whether the strategy field should be immutable or not. If we allow it to change, we should cleanup the status.strategy field and update it with the new strategy.

@fgiorgetti I think the strategy field should be immutable for now. The router does not allow updating the strategy so, the control plane should delete and re-create the multi-key listener if strategy changes. That would terminate existing TCP connections. If strategy update is required, we may add it in a follow up change including the router support for it.

Agreed. The CRD validation could be enhanced to guarantee that the field is immutable.

pwright · 2026-03-20T13:28:55Z

Help me understand immutable in this context.
If i create a CR named 'A' with strategy 'priority', I can not change the strategy without first deleting 'A' resource. Can i then recreate 'A' with strategy weighted?

fgiorgetti · 2026-03-20T13:55:56Z

Help me understand immutable in this context. If i create a CR named 'A' with strategy 'priority', I can not change the strategy without first deleting 'A' resource. Can i then recreate 'A' with strategy weighted?

Correct.

gabordozsa added this to the 2.2.0 milestone Mar 13, 2026

gabordozsa force-pushed the gabor_weighted_address_2394 branch 3 times, most recently from 1f3766e to e0d2c99 Compare March 16, 2026 14:59

Add weighted address strategy for multi-key listeners (skupperproject…

4a3197f

…#2394) Signed-off-by: Gabor Dozsa <gabor.dozsa@ibm.com>

gabordozsa force-pushed the gabor_weighted_address_2394 branch from e0d2c99 to 4a3197f Compare March 18, 2026 12:02

gabordozsa marked this pull request as ready for review March 18, 2026 12:03

gabordozsa requested review from c-kruse, fgiorgetti, nluaces and pwright as code owners March 18, 2026 12:03

pwright reviewed Mar 18, 2026

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gabordozsa requested a review from pwright March 18, 2026 18:30

fgiorgetti reviewed Mar 19, 2026

View reviewed changes

Fix comments and add more validation test

23f7c50

	WeightedStrategySpec specifies a map of routing keys to route traffic to.
	WeightedStrategySpec defines a mapping of routing keys to weights.

	routingKeysReachable is a map of routingKeys with at least one
	routingKeysReachable is a mapping of routingKeys to weights with at least one

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gabordozsa commented Mar 13, 2026

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gabordozsa commented Mar 20, 2026

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fgiorgetti commented Mar 20, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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pwright commented Mar 20, 2026

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fgiorgetti commented Mar 20, 2026

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fgiorgetti commented Mar 20, 2026 •

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