Unified mechanism for Cluster Autoscaler feature flags
Opened this issue · 3 comments
Which component are you using?:
cluster-autoscaler
Is your feature request designed to solve a problem? If so describe the problem this feature should solve.:
Enabling new features in Cluster Autoscaler usually requires a feature flag. Existing examples include --scale-down-enabled (sic!), --debugging-snapshot-enabled or --parallel-drain. These flags contribute to an already existing huge API surface of Cluster Autoscaler flags. Additionally, implementation of such flags sometimes requires passing them through a few layers of abstraction (e.g. through AutoscalingOptions), making the code harder to maintain.
Describe the solution you'd like.:
There should be a single flag to control feature enablement. Feature flags should be accessible from the code - they are global to the entire CA process anyway. I'd reuse the approach taken in kube-apiserver: http://go/kuber/blob/1ca2180f300bb83e4581c7efb02ab91b7027b6f3/staging/src/k8s.io/apiserver/pkg/util/feature/feature_gate.go#L32
Describe any alternative solutions you've considered.:
Build a custom mechanism for this. On one hand we don't really need all the alpha/beta/GA in Cluster Autoscaler, but it will be simpler to reuse what is already there (especially since CA already takes a dependency on core k8s).
Additional context.:
/help
@x13n:
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In response to this:
Which component are you using?:
cluster-autoscaler
Is your feature request designed to solve a problem? If so describe the problem this feature should solve.:
Enabling new features in Cluster Autoscaler usually requires a feature flag. Existing examples include
--scale-down-enabled(sic!),--debugging-snapshot-enabledor--parallel-drain. These flags contribute to an already existing huge API surface of Cluster Autoscaler flags. Additionally, implementation of such flags sometimes requires passing them through a few layers of abstraction (e.g. throughAutoscalingOptions), making the code harder to maintain.Describe the solution you'd like.:
There should be a single flag to control feature enablement. Feature flags should be accessible from the code - they are global to the entire CA process anyway. I'd reuse the approach taken in kube-apiserver: http://go/kuber/blob/1ca2180f300bb83e4581c7efb02ab91b7027b6f3/staging/src/k8s.io/apiserver/pkg/util/feature/feature_gate.go#L32
Describe any alternative solutions you've considered.:
Build a custom mechanism for this. On one hand we don't really need all the alpha/beta/GA in Cluster Autoscaler, but it will be simpler to reuse what is already there (especially since CA already takes a dependency on core k8s).
Additional context.:
/help
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