dataclients/kubernetes: append predicates to routes of Ingress/RouteGroup having specific annotation

[MustafaSaber]

The main purpose of this change is to allow skipper operators to dynamically add predicates to routes based on annotations key-value pairs in Kubernetes resources (metadata.annotation). This provides more flexibility in routing configuration without modifying the core Ingress or RouteGroup definitions.

Key changes:

• Added KubernetesAnnotationPredicates option & -kubernetes-annotation-predicates flag for public hostnames, which can be specified multiple times.
• Added KubernetesEastWestRangeAnnotationPredicates option & -kubernetes-east-west-range-annotation-predicates flag for internal hostnames (hostnames defined by -kubernetes-east-west-range-domains), which can be specified multiple times.
• Modified Ingress and RouteGroup clients to apply annotation predicates depending on the host
• Added test cases for new functionality

Run & test with

➜ ./bin/skipper -kubernetes -kubernetes-annotation-predicates="zalando.org/traffic-disabled=true=False()" -kubernetes-east-west-range-annotation-predicates="zalando.org/traffic-disabled=true=False()"
➜ #or
➜ ./bin/routesrv -kubernetes -kubernetes-annotation-predicates="zalando.org/traffic-disabled=true=False()" -kubernetes-east-west-range-annotation-predicates="zalando.org/traffic-disabled=true=False()"

Having both flags with same value will append configured predicates to all routes of Ingress/RouteGroup resources annotated with zalando.org/traffic-disabled: true, routes defined in:

• The spec.rules section of Ingress resources.
• Routes specified using the zalando.org/skipper-routes annotation of Ingress resources.
• The spec.routes section of RouteGroup resources.

[AlexanderYastrebov]

👍

[MustafaSaber]

👍

[szuecs]

Can you please also write in the description what "internal" hostname means?
There is a flag that defines the east-west domain and that's what we use (I didn't review the code but everything else would be a bug).