Route and Listener wildcard hostnames

[kate-osborn]

As a user of NKG with a large cluster utilizing many subdomains
I want to select the hostnames for my HTTPRoute and Gateway Listener spec using wildcard characters
So that I can easily select a set of subdomains to forward traffic to.

Acceptance

• The Route and Listener Matching is implemented as referenced below.
• If a hostname is duplicated in HTTP Route, the controller should treat the duplicates as the same hostname
• Documentation is updated
• Wildcard hostname examples is added here
• Remove FIXME

Route and Listener Matching

Empty listener hostname

empty = not set in the listener
binding hostname = the hostname that the dataplane should match on

#	listener hostname	route hostname	binding hostname
1.1	<empty>	foo.example.com	foo.example.com
1.2	<empty>	*.example.com	*.example.com

Regular listener hostname

#	listener hostname	route hostname	binding hostname
2.1	foo.example.com	foo.example.com	foo.example.com
2.2	foo.example.com	foo.example.org	none
2.3	foo.example.com	*.foo.example.com	none
2.4	foo.example.com	*.example.com	foo.example.com

Wildcard listener hostname

#	listener hostname	route hostname	binding hostname
3.1	*.example.com	*.example.com	*.example.com
3.2	*.example.com	foo.example.com	foo.example.com
3.3	*.example.com	example.com	none
3.4	*.example.com	*.com	*.example.com
3.5	*.example.com	*.foo.example.com	*.foo.example.com

Empty list of route hostnames

#	listener hostname	route hostname	binding hostname
4.1	example.com	empty list	example.com
4.2	*.example.com	empty list	*.example.com
4.3	<empty>	empty list	<any>

<any> means it will match any host header.

Links

• https://github.com/kubernetes-sigs/gateway-api/blob/20be22d3a2976374772170a6a55a9c8228d1e8c8/apis/v1beta1/httproute_types.go#L59
• Conformance tests
  • https://github.com/kubernetes-sigs/gateway-api/blob/7631139b1ea4beaf575a49f56c56aa26f1e11e22/conformance/tests/httproute-hostname-intersection.go#L35 passes , however, empty section Name i is required.
  • https://github.com/kubernetes-sigs/gateway-api/blob/7631139b1ea4beaf575a49f56c56aa26f1e11e22/conformance/tests/httproute-listener-hostname-matching.go#L33 passes

[kate-osborn]

This issue is blocked by #479

[mpstefan]

Questions for discussion:

• Is our implementation going to be specific for HTTPRoute or all routes?
• Any difference for TLS listeners?
• What does "duplicated hostnames in HTTPRoute -> silently ignore" mean? We only take the first one? Match to both?
• Do we want to include conformance tests in acceptance criteria?
  • https://github.com/kubernetes-sigs/gateway-api/blob/7631139b1ea4beaf575a49f56c56aa26f1e11e22/conformance/tests/httproute-hostname-intersection.go#L35 passes , however, empty section Name i is required.
  • https://github.com/kubernetes-sigs/gateway-api/blob/7631139b1ea4beaf575a49f56c56aa26f1e11e22/conformance/tests/httproute-listener-hostname-matching.go#L33 passes
• Old notes?
  • server_name collisions
  • long hostnames

Documented edge case:

• correct conflict handling across multiple listeners
  listener 1 foo.example.com
  listener 2 *.example.com
  hr1 foo.example.com
  hr2 foo.example.com

• none of route's hostname matches the listener hostname -> Accepted False NoMatchingListener

• some of the route's hostname don't match the listener hostname -> ?