Linkerd traffic split with Nginx Ingress Controller

tl;dr: The nginx ingress requires a Service resource to have an Endpoint resource in order to be considered a valid destination for traffic. The architecture in the repo creates three Service resources, one of which acts as an apex and has no Endpoint resources because it has no selectors, so the nginx ingress won't send traffic to it, and the leaf services will not get traffic as a result.

The example in the repo follows the SMI Spec by defining a single apex service and two leaf services. The web-apex service does not have any endpoints, so nginx will not send traffic to it.

According to the SMI Spec services can be self-referential, which means that a service can be both an apex and a leaf service, so to use the nginx ingress with this example, you can modify the TrafficSplit definition to change the spec.service value from web-apex to web-svc:

apiVersion: split.smi-spec.io/v1alpha1kind: TrafficSplitmetadata:  name: web-svc-ts  namespace: emojivotospec:  # The root service that clients use to connect to the destination application.  service: web-svc  # Services inside the namespace with their own selectors, endpoints and configuration.  backends:  - service: web-svc    # Identical to resources, 1 = 1000m    weight: 500m  - service: web-svc-2    weight: 500m

I have raised this question in the Linkerd Slack channel and got this fixed with the wonderful support from the community. Seems Nginx doesn't like the service which doesn't have an endpoint. My configuration was correct and asked to change the service pointed in the traffic split to a service with an endpoint and it fixed the issue.

In a nutshell, my traffic split was configured with web-svc and web-svc-2 services. I have changed the traffic split spec.service to the same web-svc and it worked

Here is the traffic split configuration after the update.

apiVersion: split.smi-spec.io/v1alpha1kind: TrafficSplitmetadata:  name: web-svc-ts  namespace: emojivotospec:  # The root service that clients use to connect to the destination application.  service: web-svc  # Services inside the namespace with their own selectors, endpoints and configuration.  backends:  - service: web-svc    # Identical to resources, 1 = 1000m    weight: 500m  - service: web-svc-2    weight: 500m

Kudos to the Linkerd team who supported me to fix this issue. It is working like a charm.