Introduce support for section-specific annotations in HTTPRoute that propagate to specific route rule XDS metadata

[Tharsanan1]

Description

Currently using httproute annotations i can add static xds metadata. But when we need to add specific static metadata to a specific xds route rule this is not supported. for this I m proposing the following annotation structure.

gateway.envoyproxy.io/rule.<rule-index>.match.<match-index>.<key>: <value>

• rule.i: Targets the i-th rule in .spec.rules.
• match.j: Targets the j-th match entry in .spec.rules[i].matches.
• key: The metadata key you want applied in that scope.

Example

metadata:
  annotations:
    gateway.envoyproxy.io/not-rule-specific: value
    gateway.envoyproxy.io/rule.0.match.0.logging-level: debug
    gateway.envoyproxy.io/rule.1.match.1.logging-level: warn

Resulting XDS Metadata Translation:

name: httproute/namespace/myroute/rule/0/match/0/*
metadata:
  filter_metadata:
    envoy-gateway:
      resources:
        - kind: HTTPRoute
          name: myroute
          namespace: myns
          annotations:
            logging-level: debug
            not-rule-specific: value
...
...
name: httproute/namespace/myroute/rule/1/match/1/*
metadata:
  filter_metadata:
    envoy-gateway:
      resources:
        - kind: HTTPRoute
          name: myroute
          namespace: myns
          annotations:
            logging-level: warn
            not-rule-specific: value

Shall I implement this improvement and send a PR?

This kind of improvement is marked as future enhancement in the doc. link

[zirain]

I don't think annotation is the right direction.

[Tharsanan1]

@zirain in the EnvoyGateway document it says in the future, it might be supported through annotations thats why, I have proposed this design. What do you think the right way to do this?

[arkodg]

@Tharsanan1 I believe the design doc is referring to mapping a HTTPRoute Rule Name to a xDS Route metadata, but you're referring to bringing additional user specified kay, value pairs and setting them for a xDS Route metadata which maps to a specific HTTP Route Rule.
-1 to the approach you've mentioned, you could achieve the same goal by splitting up the rule into a dedicated HTTPRoute