agentgateway: better defaults in deployment

[howardjohn]

Description

Setting replicas breaks things like HPA, etc. For some reason in Envoy, probably some notion of backwards compat, we made the user have to opt-in to omitting it; this doesn't really make sense so default it in agentgateway.

Enable metrics scraping

Change Type

/kind new_feature

Changelog

NONE

Additional Notes

[Copilot]

Pull Request Overview

This PR improves the default deployment configuration for agentgateway by removing hardcoded replica counts and enabling Prometheus metrics scraping. The changes allow for better compatibility with Kubernetes autoscaling features like HPA while providing observability through metrics collection.

• Removes hardcoded replicas: 1 setting to allow HPA and other autoscaling mechanisms to function properly
• Adds Prometheus annotations for metrics scraping on port 15020 with path /metrics

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
pkg/deployer/gateway_parameters.go	Sets deployment replicas to nil in agentgateway parameters to enable autoscaling
internal/kgateway/helm/kgateway/templates/gateway/agent-gateway-deployment.yaml	Adds Prometheus scraping annotations to pod template
test/deployer/testdata/agentgateway-out.yaml	Updated test output reflecting removed replicas and added Prometheus annotations
test/deployer/testdata/agentgateway-omitdefaultsecuritycontext-ref-gwp-on-gw-out.yaml	Updated test output for omit security context variant
test/deployer/testdata/agentgateway-omitdefaultsecuritycontext-out.yaml	Updated test output for omit security context variant

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