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Empty list attributes cause perpetual diffs/replacements due to null vs [] mismatch #2997

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Empty list attributes cause perpetual diffs/replacements due to null vs [] mismatch #2997

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ed20c07
fix for empty list state handling
cgeiaws Feb 6, 2026
7de2830
remove tests
cgeiaws Feb 6, 2026
070d867
remove bin file and re-add test
cgeiaws Feb 6, 2026
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14 changes: 12 additions & 2 deletions internal/generic/translate.go
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Original file line number Diff line number Diff line change
Expand Up @@ -226,6 +226,11 @@ func (t toTerraform) valueFromRaw(ctx context.Context, schema typeAtTerraformPat
//
case []any:
if len(v) == 0 {
// Return an empty list/set instead of nil to preserve empty collections in state.
// This prevents perpetual diffs when the config has [] but AWS returns an empty array.
if typ.Is(tftypes.List{}) || typ.Is(tftypes.Set{}) || typ.Is(tftypes.Tuple{}) {
return tftypes.NewValue(typ, []tftypes.Value{}), nil
}
return tftypes.NewValue(typ, nil), nil
}

Expand Down Expand Up @@ -305,10 +310,15 @@ func (t toTerraform) valueFromRaw(ctx context.Context, schema typeAtTerraformPat
path = path.WithoutLastStep()
}
if isObject {
// Set any missing attributes to Null.
// Set any missing attributes to Null, or empty list/set for collection types.
// This prevents perpetual diffs when the config has [] but AWS omits the field.
for k, t := range typ.(tftypes.Object).AttributeTypes {
if _, ok := vals[k]; !ok {
vals[k] = tftypes.NewValue(t, nil)
if t.Is(tftypes.List{}) || t.Is(tftypes.Set{}) {
vals[k] = tftypes.NewValue(t, []tftypes.Value{})
} else {
vals[k] = tftypes.NewValue(t, nil)
}
}
}
}
Expand Down
8 changes: 6 additions & 2 deletions internal/generic/translate_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -235,6 +235,8 @@ func TestTranslateToTerraform(t *testing.T) {
"Number": float64(42),
"Ports": []any{},
},
// Empty lists from AWS should be preserved as empty lists (not nil)
// to prevent perpetual diffs when config has [] but AWS returns []
ExpectedValue: tftypes.NewValue(tftypes.Object{
AttributeTypes: map[string]tftypes.Type{
"arn": tftypes.String,
Expand All @@ -248,7 +250,7 @@ func TestTranslateToTerraform(t *testing.T) {
"identifier": tftypes.NewValue(tftypes.String, nil),
"name": tftypes.NewValue(tftypes.String, "testing"),
"number": tftypes.NewValue(tftypes.Number, 42),
"ports": tftypes.NewValue(tftypes.List{ElementType: tftypes.Number}, nil),
"ports": tftypes.NewValue(tftypes.List{ElementType: tftypes.Number}, []tftypes.Value{}),
}),
},
{
Expand All @@ -260,6 +262,8 @@ func TestTranslateToTerraform(t *testing.T) {
"Name": "testing",
"Number": float64(42),
},
// Missing list fields from AWS should be set to empty list (not null)
// to prevent perpetual diffs when config has [] but AWS omits the field
ExpectedValue: tftypes.NewValue(tftypes.Object{
AttributeTypes: map[string]tftypes.Type{
"arn": tftypes.String,
Expand All @@ -273,7 +277,7 @@ func TestTranslateToTerraform(t *testing.T) {
"identifier": tftypes.NewValue(tftypes.String, nil),
"name": tftypes.NewValue(tftypes.String, "testing"),
"number": tftypes.NewValue(tftypes.Number, 42),
"ports": tftypes.NewValue(tftypes.List{ElementType: tftypes.Number}, nil),
"ports": tftypes.NewValue(tftypes.List{ElementType: tftypes.Number}, []tftypes.Value{}),
}),
},
{
Expand Down