feat: introduce GatewayConfig CRD for gateway-scoped configuration

[sqaisar]

Description

Introduce GatewayConfig CRD for gateway-scoped configuration of the external processor. Adds controller lifecycle handling (including finalizer management), deprecates AIGatewayRoute-level resource configuration in favor of GatewayConfig, and updates docs with migration guidance and new options.

Example

apiVersion: aigateway.envoyproxy.io/v1alpha1
kind: GatewayConfig
metadata:
  name: my-gateway-config
  namespace: default
spec:
  extProc:
   kubernetes:
      env:
        - name: OTEL_EXPORTER_OTLP_ENDPOINT
          value: "http://otel-collector:4317"
      resources:
        requests:
          cpu: "100m"
          memory: "128Mi"
        limits:
          cpu: "500m"
          memory: "512Mi"
---
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: my-gateway
  namespace: default
  annotations:
    aigateway.envoyproxy.io/gateway-config: my-gateway-config
spec:
  gatewayClassName: envoy-gateway
  listeners:
    - name: http
      protocol: HTTP
      port: 8080

Related Issues/PRs (if applicable)

Fixes [1]

Special notes for reviewers (if applicable)

Docs, controller, and CRD changes included; route-level resources are deprecated—see migration guidance in docs.

1: #1552

[mathetake]

Thank you for taking a shot at this!

[nacx]

Just reviewed the API for now and left one comment.

Apart from that, this GatewayConfig object is only relevant for Kubernets, but not in standalone modes (at least for now). Would it make sense to convey that in the API? For example, the Envoy Gateaay infrastructure resources have the "provider" concept and settings are under a kubernetes config know.

Something like:

apiVersion: aigateway.envoyproxy.io/v1alpha1
kind: GatewayConfig
metadata:
  name: comprehensive-config
  namespace: default
spec:
  kubernetes:  
    extProc:
      env:
        (...)

or

apiVersion: aigateway.envoyproxy.io/v1alpha1
kind: GatewayConfig
metadata:
  name: comprehensive-config
  namespace: default
spec:
  extProc:  
    kubernetes:
      env:
        (...)

WDYT?

[sqaisar]

Thank you for taking a shot at this!

Thankyou for quickly reviewing the changes. I've resolved all of them. Please take a look.

[mathetake]

looking good so far!

[sqaisar]

@mathetake I've updated the type to GatewayConfig.extProc.kubernetes
for now all changes looks concluded. Please review.

[mathetake]

Looks good to me modulo a few comments. Thank you so much for working on this! I will defer to @nacx for the rest as i will not be available to review at least for the next 48 hours

[sqaisar]

Added more tests to make up for coverage.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 52.11864% with 113 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.81%. Comparing base (502d8ad) to head (8b34fe7).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/controller/gateway_mutator.go	61.00%	31 Missing and 8 partials ⚠️
...ers/externalversions/api/v1alpha1/gatewayconfig.go	0.00%	27 Missing ⚠️
...oned/typed/api/v1alpha1/fake/fake_gatewayconfig.go	0.00%	16 Missing ⚠️
internal/controller/gateway_config.go	85.50%	7 Missing and 3 partials ⚠️
...tset/versioned/typed/api/v1alpha1/gatewayconfig.go	0.00%	9 Missing ⚠️
...lpha1/client/listers/api/v1alpha1/gatewayconfig.go	0.00%	4 Missing ⚠️
...ientset/versioned/typed/api/v1alpha1/api_client.go	0.00%	2 Missing ⚠️
...rsioned/typed/api/v1alpha1/fake/fake_api_client.go	0.00%	2 Missing ⚠️
...formers/externalversions/api/v1alpha1/interface.go	0.00%	2 Missing ⚠️
...lpha1/client/informers/externalversions/generic.go	0.00%	2 Missing ⚠️

❌ Your patch status has failed because the patch coverage (52.11%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1623      +/-   ##
==========================================
- Coverage   83.41%   82.81%   -0.61%     
==========================================
  Files         138      143       +5     
  Lines       12447    12668     +221     
==========================================
+ Hits        10383    10491     +108     
- Misses       1431     1533     +102     
- Partials      633      644      +11     

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