[Feature] Support adding an observer role in FE to improve query load balancing and scale read workloads

[zhaohehuhu]

Description

Support adding a read-only observer role in FE via the K8s Operator to scale read capacity and improve query load balancing.

associated with this PR(StarRocks/starrocks#67778)

Related Issue(s)

No.

Checklist

For operator, please complete the following checklist:

• run make generate to generate the code.
• run golangci-lint run to check the code style.
• run make test to run UT.
• run make manifests to update the yaml files of CRD.

For helm chart, please complete the following checklist:

• make sure you have updated the values.yaml
  file of starrocks chart.
• In scripts directory, run bash create-parent-chart-values.sh to update the values.yaml file of the parent
  chart( kube-starrocks chart).

[zhaohehuhu]

@yandongxiao @kevincai plz help review

[Copilot]

Pull request overview

This pull request adds support for an Observer role in FE (Frontend) via the Kubernetes Operator to scale read capacity and improve query load balancing. The Observer role is implemented as a configurable field that can be set to specify the number of observer nodes.

Key changes:

• Added ObserverNumber field to StarRocksFeSpec API with a getter method that defaults to 0
• Exposed observer number as an environment variable (OBSERVER_NUMBER) to FE pods
• Updated CRD schemas to include the new observerNumber field
• Updated Helm chart values.yaml files with commented examples for the new configuration option

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
pkg/apis/starrocks/v1/starrockscluster_types.go	Adds ObserverNumber field to StarRocksFeSpec and implements GetObserverNumber() method with default value of 0
pkg/apis/starrocks/v1/zz_generated.deepcopy.go	Auto-generated deep copy implementation for the new ObserverNumber pointer field
pkg/apis/starrocks/v1/labels.go	Adds OBSERVER_NUMBER constant for the environment variable name
pkg/apis/starrocks/v1/load_type.go	Minor whitespace cleanup (removed blank lines)
pkg/k8sutils/templates/pod/spec.go	Updates Envs function to set OBSERVER_NUMBER environment variable for FE pods using the new field
pkg/k8sutils/templates/pod/spec_test.go	Adds test coverage for the OBSERVER_NUMBER environment variable in FE spec
config/crd/bases/starrocks.com_starrocksclusters.yaml	Adds observerNumber field definition to the CRD schema
deploy/starrocks.com_starrocksclusters.yaml	Adds observerNumber field definition to the deployed CRD schema
helm-charts/charts/kube-starrocks/charts/starrocks/values.yaml	Adds commented example for observerNumber configuration
helm-charts/charts/kube-starrocks/values.yaml	Adds commented example for observerNumber configuration in parent chart

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[kevincai]

don't try to use FE_OBSERVER_NUMBER to hack the current fe_entry_point.sh

It is so dangerous that a single improper env var update can ruin the entire cluster.

[zhaohehuhu]

don't try to use FE_OBSERVER_NUMBER to hack the current fe_entry_point.sh

It is so dangerous that a single improper env var update can ruin the entire cluster.

Got it. In that case, we may need to add a new FE observer component.

[kyle-goodale-klaviyo]

This is much needed, thank you!

[zhaohehuhu]

This is much needed, thank you!

I still need some time to test this feature. Thanks!

[zhaohehuhu]

@kevincai @yandongxiao plz help review. Thanks!