feat: add support for helm 4 --server-side upgrade flag (#2641)

* feat: add support for helm 4 --server-side upgrade flag

Add support for the helm 4 upgrade flag --server-side which accepts
"true", "false", or "auto" (default "auto"). This allows users to
explicitly control server-side apply behavior, which is needed for
releases originally installed with Helm 3 and being managed with Helm 4.

The flag can be configured via:
- CLI: --server-side flag on sync, apply, and diff commands
- helmDefaults.serverSide in helmfile.yaml
- releases[].serverSide per-release override

Precedence: release-level > CLI flag > helmDefaults.
Errors are returned when serverSide is set but running Helm 3, or when
an invalid value is provided.

Closes #2640

Signed-off-by: yxxhero <aiopsclub@163.com>

* test: update TestGenerateID expected hashes for new ServerSide field

Adding ServerSide *string to ReleaseSpec changes spew's %#v output and
shifts the FNV hash used by generateValuesID. Update the hard-coded want
values to the new deterministic hashes.

Signed-off-by: yxxhero <aiopsclub@163.com>

---------

Signed-off-by: yxxhero <aiopsclub@163.com>

pkg/app/app.go

@@ -1816,6 +1816,7 @@ func (a *App) apply(r *Run, c ApplyConfigProvider) (bool, bool, []error) {
 		SkipSchemaValidation:    c.SkipSchemaValidation(),
 		SuppressOutputLineRegex: c.SuppressOutputLineRegex(),
 		TakeOwnership:           c.TakeOwnership(),
+		ServerSide:              c.ServerSide(),
 		DetectedKubeVersion:     detectedKubeVersion,
 	}
 
@@ -1937,6 +1938,7 @@ Do you really want to apply?
 					SyncArgs:             c.SyncArgs(),
 					HideNotes:            c.HideNotes(),
 					TakeOwnership:        c.TakeOwnership(),
+					ServerSide:           c.ServerSide(),
 					SyncReleaseLabels:    c.SyncReleaseLabels(),
 					TrackMode:            c.TrackMode(),
 					TrackTimeout:         c.TrackTimeout(),
@@ -2096,6 +2098,7 @@ func (a *App) diff(r *Run, c DiffConfigProvider) (*string, bool, bool, []error)
 			SkipSchemaValidation:    c.SkipSchemaValidation(),
 			SuppressOutputLineRegex: c.SuppressOutputLineRegex(),
 			TakeOwnership:           c.TakeOwnership(),
+			ServerSide:              c.ServerSide(),
 			DetectedKubeVersion:     detectedKubeVersion,
 		}
 
@@ -2335,6 +2338,7 @@ func (a *App) SyncState(r *Run, c SyncConfigProvider) (bool, bool, []error) {
 				SkipSchemaValidation:    diffC.SkipSchemaValidation(),
 				SuppressOutputLineRegex: diffC.SuppressOutputLineRegex(),
 				TakeOwnership:           diffC.TakeOwnership(),
+				ServerSide:              diffC.ServerSide(),
 				DetectedKubeVersion:     detectedKubeVersion,
 			}
 			infoMsgPtr, _, _, diffErrs := r.diff(false, diffC.DetailedExitcode(), diffC, diffOpts)
@@ -2422,6 +2426,7 @@ Do you really want to sync?
 					SyncArgs:             c.SyncArgs(),
 					HideNotes:            c.HideNotes(),
 					TakeOwnership:        c.TakeOwnership(),
+					ServerSide:           c.ServerSide(),
 					SkipSchemaValidation: c.SkipSchemaValidation(),
 					SyncReleaseLabels:    c.SyncReleaseLabels(),
 					TrackMode:            c.TrackMode(),

pkg/app/app_test.go

@@ -2539,6 +2539,7 @@ type applyConfig struct {
 	showOnly                 []string
 	hideNotes                bool
 	takeOwnership            bool
+	serverSide               string
 	syncReleaseLabels        bool
 	enforceNeedsAreInstalled bool
 	trackMode                string
@@ -2755,6 +2756,10 @@ func (a applyConfig) TakeOwnership() bool {
 	return a.takeOwnership
 }
 
+func (a applyConfig) ServerSide() string {
+	return a.serverSide
+}
+
 func (a applyConfig) SyncReleaseLabels() bool {
 	return a.syncReleaseLabels
 }

pkg/app/config.go

@@ -49,6 +49,7 @@ type ApplyConfigProvider interface {
 	Cascade() string
 	HideNotes() bool
 	TakeOwnership() bool
+	ServerSide() string
 	SuppressOutputLineRegex() []string
 
 	Values() []string
@@ -108,6 +109,7 @@ type SyncConfigProvider interface {
 	PostRendererArgs() []string
 	HideNotes() bool
 	TakeOwnership() bool
+	ServerSide() string
 	Cascade() string
 
 	Values() []string
@@ -176,6 +178,7 @@ type DiffConfigProvider interface {
 	Context() int
 	DiffOutput() string
 	TakeOwnership() bool
+	ServerSide() string
 
 	concurrencyConfig
 	valuesControlMode

pkg/app/diff_test.go

@@ -47,6 +47,7 @@ type diffConfig struct {
 	reuseValues              bool
 	logger                   *zap.SugaredLogger
 	takeOwnership            bool
+	serverSide               string
 	enforceNeedsAreInstalled bool
 }
 
@@ -188,6 +189,9 @@ func (a diffConfig) SuppressOutputLineRegex() []string {
 func (a diffConfig) TakeOwnership() bool {
 	return a.takeOwnership
 }
+func (a diffConfig) ServerSide() string {
+	return a.serverSide
+}
 
 func (a diffConfig) EnforceNeedsAreInstalled() bool {
 	return a.enforceNeedsAreInstalled