From 56c9d3fbfaaeaa36b305c2f89d3dc830240f1daf Mon Sep 17 00:00:00 2001
From: Arnob kumar saha <arnob@appscode.com>
Date: Fri, 30 Oct 2026 18:34:48 +0600
Subject: [PATCH] Drop null overrides of chart defaults in MergeValues

MergeValues merges chart defaults with user values itself and callers
blank chart.Values, so Helm's coalesce never removes keys set to null.
The nulls then reach JSON schema validation (e.g. 'got null, want
integer'). Delete null overrides of chart defaults, as the helm CLI does.

Signed-off-by: Arnob kumar saha <arnob@appscode.com>
---
 pkg/values/options.go | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/pkg/values/options.go b/pkg/values/options.go
index f532aab93..6b2b29f5a 100644
--- a/pkg/values/options.go
+++ b/pkg/values/options.go
@@ -94,6 +94,10 @@ func (opts *Options) MergeValues(chrt *chart.Chart) (map[string]any, error) {
 	if err := yaml.Unmarshal(baseFile.Data, &base); err != nil {
 		return nil, errors.Wrapf(err, "failed to parse %s", opts.ValuesFile)
 	}
+	defaults := map[string]any{}
+	if err := yaml.Unmarshal(baseFile.Data, &defaults); err != nil {
+		return nil, errors.Wrapf(err, "failed to parse %s", opts.ValuesFile)
+	}
 
 	// User specified a values files via -f/--values
 	for _, bytes := range opts.ValueBytes {
@@ -127,9 +131,34 @@ func (opts *Options) MergeValues(chrt *chart.Chart) (map[string]any, error) {
 		}
 	}
 
+	// Callers blank chart.Values before handing these to Helm, so Helm's own
+	// coalesce never sees the defaults and can't drop null overrides; do it here
+	// to keep `key=null` deleting a chart default as it does with the helm CLI.
+	deleteNullOverrides(base, defaults)
+
 	return base, nil
 }
 
+func deleteNullOverrides(vals, defaults map[string]any) {
+	for k, v := range vals {
+		dv, ok := defaults[k]
+		if !ok {
+			continue
+		}
+		if v == nil {
+			delete(vals, k)
+			continue
+		}
+		vm, ok := v.(map[string]any)
+		if !ok {
+			continue
+		}
+		if dm, ok := dv.(map[string]any); ok {
+			deleteNullOverrides(vm, dm)
+		}
+	}
+}
+
 func MergeMaps(a, b map[string]any) map[string]any {
 	out := make(map[string]any, len(a))
 	for k, v := range a {