fix: let HPA manage envoy-gateway replicas when enabled

[juhosyrjanen]

Description:

This change wraps the Deployment’s spec.replicas field in: {{- if not .Values.hpa.enabled }}, so that the replicas value is only rendered when Horizontal Pod Autoscaling is disabled.

When an HPA is managing the replica count, this prevents GitOps tools from continually attempting to reconcile the Deployment back to a fixed replica value, eliminating unnecessary drift.

Validation:

With generated temporary Helm values:

helm template test charts/gateway-helm \
   -f /tmp/gateway-values.yaml \
   --set hpa.enabled=false \
   --show-only templates/envoy-gateway-deployment.yaml | grep replicas
 replicas: 1

When HPA is enabled:

helm template test charts/gateway-helm \
    -f /tmp/gateway-values.yaml \
    --set hpa.enabled=true \
    --show-only templates/envoy-gateway-deployment.yaml | grep replicas

Fixes #7560

[arkodg]

thanks, can you add a test in https://github.com/envoyproxy/gateway/tree/main/test/helm as well as run make testdata && make generate

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.31%. Comparing base (bd27a16) to head (d3a6bc2).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7565      +/-   ##
==========================================
+ Coverage   72.28%   72.31%   +0.03%     
==========================================
  Files         232      232              
  Lines       34114    34114              
==========================================
+ Hits        24658    24670      +12     
+ Misses       7679     7672       -7     
+ Partials     1777     1772       -5     

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[juhosyrjanen]

thanks, can you add a test in https://github.com/envoyproxy/gateway/tree/main/test/helm as well as run make testdata && make generate

@arkodg Added a new test for when HPA is disabled and removed the replica specification from the original HPA test. 👍

[arkodg]

@envoyproxy/gateway-maintainers @envoyproxy/gateway-reviewers should we disable replica when hpa is enabled or ask the user to comment out replica #6249 (comment)

[juhosyrjanen]

Seems like me local linter prefers " over '... I reran the generation, my bad!

[cnvergence]

hi @juhosyrjanen :)
I think this is a correct approach as per https://argo-cd.readthedocs.io/en/stable/user-guide/best_practices/#leaving-room-for-imperativeness
Seems like you need to run helm-generate again

[juhosyrjanen]

hi @juhosyrjanen :) I think this is a correct approach as per https://argo-cd.readthedocs.io/en/stable/user-guide/best_practices/#leaving-room-for-imperativeness Seems like you need to run helm-generate again

Oh hi there! :) I will update this as per your comment in a bit!

[kkk777-7]

It seems that other OSS projects also omit the replicas field when HPA is enabled, so this approach looks appropriate.

istio : https://github.com/istio/istio/blob/master/manifests/charts/gateway/templates/deployment.yaml#L13
coredns : https://github.com/coredns/helm/pull/116/files

[zirain]

/retest