Set proper host and port in generated Kong services

[randmonkey]

Is there an existing issue for this?

• I have searched the existing issues

Problem Statement

Currently KIC sets host of generated Kong service to <service-name>.<service-namespace>.<port>.svc, and does not set port field (thus port will be set to the deafult value 80). Although the real backends are specified by upstreams of the service, and the host and port does not affect real traffic, it will bring much confusion when it displays to users, and may bring additional issues to plugins.
Now we need to set the host and port to make less difference as using Kong without KIC, to bring less confusion to the visibility layer (like displaying on Konnect or Kong manager) and plugins.

Proposed Solution

• set host to the real (resolvable) host of the backend service if possible

  • If there are multiple backend services, like multiple backendRefs in gateway API *Route?

• set port to be same as the real backend service port if possible

  • If the port could not be set as a number (like specifying port in string mode), what should we put here?

Additional information

No response

Acceptance Criteria

• host of generated Kong service is set to a resolvable host of the backend service if possible
• port of generated Kong service is set to the real port number of backend service if possible

[rainest]

host must be the upstream name with the current Kong implementation, and I don't expect that to change.

Upstreams are implemented as a sort of pseudo DNS server. Kong's internal hostname resolution first searches for the service hostname in the upstream name list before sending it out to the external resolver. Changing the hostname would mean that we attempt to resolve externally and ignore our upstreams.