Is this the right place to submit this?

• This is not a security vulnerability or a crashing bug
• This is not a question about how to use Istio

Bug Description

Running Istio in multi-primary setup.

When using localityLbSetting enabled with outlierDetection traffic is being routed to local cluster only, but some requests are getting timeout errors.

When either a) outlierDetection is removed and localityLbSetting is enabled or b) outlierDetection is present and localityLbSetting is disabled, traffic is being balanced between two clusters

Screenshots of application connection timeout error logs and proxy sidecars metrics shows the correlation when outlierDetection is removed - errors disappear, but traffic is being balanced between two clusters.

Interestingly enough, localityLbSetting enablement adds to EnvoyProxy clusters config:

  commonLbConfig:
    localityWeightedLbConfig: {}

While adding outlierDetection, under the hood healthyPanicThreshold is being added to EnvoyProxy config:

  commonLbConfig:
    healthyPanicThreshold: {}
    localityWeightedLbConfig: {}

Additionally all endpoints have priority assigned to them.

I'm interested what magic does outlierDetection and localityLbSetting combo adds that outgoing requests starting to time out?

Version

$ istioctl version
client version: 1.19.0
control plane version: 1.22.2
data plane version: 1.22.2 (2306 proxies)

$ kubectl version --short
Client Version: v1.25.10
Kustomize Version: v4.5.7
Server Version: v1.26.7

Additional Information

No response