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Refactor ScaleExtender + block scale-to-zero #2

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8a02364
Refactor ScaleExtender to use unified dao.Scaler
s4ros Apr 30, 2026
708856c
scale: refuse to open scale dialog when current count is unknown
s4ros May 24, 2026
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47 changes: 30 additions & 17 deletions internal/view/scale_extender.go
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Original file line number Diff line number Diff line change
Expand Up @@ -109,20 +109,13 @@ func (s *ScaleExtender) replicasFromReady(_ string) (string, error) {
}

func (s *ScaleExtender) replicasFromScaleSubresource(sel string) (string, error) {
res, err := dao.AccessorFor(s.App().factory, s.GVR())
if err != nil {
return "", err
}

replicasGetter, ok := res.(dao.ReplicasGetter)
if !ok {
return "", fmt.Errorf("expecting a replicasGetter resource for %q", s.GVR())
}

var scaler dao.Scaler
scaler.Init(s.App().factory, s.GVR())

ctx, cancel := context.WithTimeout(context.Background(), s.App().Conn().Config().CallTimeout())
defer cancel()

replicas, err := replicasGetter.Replicas(ctx, sel)
replicas, err := scaler.Replicas(ctx, sel)
if err != nil {
return "", err
}
Expand All @@ -131,7 +124,9 @@ func (s *ScaleExtender) replicasFromScaleSubresource(sel string) (string, error)
}

func (s *ScaleExtender) makeScaleForm(fqns []string) (*tview.Form, error) {
factor := "0"
// Use empty string as the "unknown" sentinel so a legitimate current
// replica count of 0 (e.g., paused workload) is not treated as failure.
factor := ""
if len(fqns) == 1 {
// If the CRD resource supports scaling, then first try to
// read the replicas directly from the CRD.
Expand All @@ -144,14 +139,30 @@ func (s *ScaleExtender) makeScaleForm(fqns []string) (*tview.Form, error) {

// For built-in resources or cases where we can't get the replicas from the CRD, we can
// only try to get the number of copies from the READY field.
if factor == "0" {
var readyErr error
if factor == "" {
replicas, err := s.replicasFromReady(fqns[0])
if err != nil {
return nil, err
if err == nil {
factor = replicas
} else {
readyErr = err
slog.Warn("Unable to read replicas from ready column", slogs.Error, err)
}
}

factor = replicas
// Refuse to open the dialog when we cannot determine the current
// replica count — otherwise a user hitting OK without editing would
// silently scale the workload to zero.
if factor == "" {
if readyErr != nil {
return nil, fmt.Errorf("unable to determine current replica count: %w", readyErr)
}
return nil, fmt.Errorf("unable to determine current replica count for %s", fqns[0])
}
} else {
// Bulk-scale: there is no single "current" value to pre-fill, so the
// user must explicitly enter a target. Keep the documented default.
factor = "0"
}

styles := s.App().Styles.Dialog()
Expand Down Expand Up @@ -222,7 +233,9 @@ func (s *ScaleExtender) scale(ctx context.Context, path string, replicas int32)
}
scaler, ok := res.(dao.Scalable)
if !ok {
return fmt.Errorf("expecting a scalable resource for %q", s.GVR())
var genericScaler dao.Scaler
genericScaler.Init(s.App().factory, s.GVR())
return genericScaler.Scale(ctx, path, replicas)
}

return scaler.Scale(ctx, path, replicas)
Expand Down