Add path/uri matching support to setHeaderRoute

[ruszu]

Description

Currently, setHeaderRoute only supports matching by headers (headerName + headerValue), but does not support path/URI matching.

Use Case

When using a shared host with multiple services (e.g., API gateway pattern), setHeaderRoute captures all requests with the specified header, regardless of the path. This breaks other services on the same host.

Example:

Host api-gateway.example.com serves multiple services:

/service-a/* → service-a
/service-b/* → service-b

When deploying service-a with canary + setHeaderRoute, requests to /service-b/* with the header are incorrectly routed to service-a canary.

Current Workaround

Use VirtualService delegation to isolate the path scope before Argo Rollouts applies header routing. This works but adds complexity.

[kostis-codefresh]

Header based routing code currently exists in two places.

• Argo rollouts core (only for providers that support it i.e. istio)
• Gateway API plugin (for providers that support the Gateway API spec)

I think what you ask must be implemented in the new canary step plugin instead of trying to adapt existing code.

See https://argo-rollouts.readthedocs.io/en/stable/features/canary/plugins/