consider allowing Contour to manage the Envoy Service in statically provisioned Gateway mode

When Contour is dynamically provisioned by the Gateway Provisioner, the Provisioner acts as the reconciler for Gateway Listeners, and adjusts the Envoy Service spec as needed to expose the proper ports. However, when Contour is statically provisioned, there is no Gateway Provisioner in the picture, so the user must manually keep the Envoy Service spec in sync with the Gateway Listeners.

We've discussed in the past allowing Contour to manage the Envoy Service spec in this scenario. I think this is worth revisiting, as it is technically feasible and would eliminate a point of friction for folks who want to statically provision Contour, but still want the benefit of dynamic Gateway Listeners.

Start by reviewing how statically provisioned Contour handles Gateway Listeners and how the Envoy Service spec is currently maintained, then compare that with the Gateway Provisioner’s reconciliation behavior. Define the required Service updates for dynamic Gateway Listeners and verify that static provisioning keeps the Service synchronized without manual changes.

Written by the indexing model from the issue text.