Helm client/SDK support server-side apply

Signed-off-by: George Jenkins <gvjenkins@gmail.com>

pkg/action/action.go

@@ -520,3 +520,10 @@ func (cfg *Configuration) Init(getter genericclioptions.RESTClientGetter, namesp
 func (cfg *Configuration) SetHookOutputFunc(hookOutputFunc func(_, _, _ string) io.Writer) {
 	cfg.HookOutputFunc = hookOutputFunc
 }
+
+func determineReleaseSSApplyMethod(serverSideApply bool) release.ApplyMethod {
+	if serverSideApply {
+		return release.ApplyMethodServerSideApply
+	}
+	return release.ApplyMethodClientSideApply
+}

pkg/action/action_test.go

@@ -946,3 +946,8 @@ func TestRenderResources_NoPostRenderer(t *testing.T) {
 	assert.NotNil(t, buf)
 	assert.Equal(t, "", notes)
 }
+
+func TestDetermineReleaseSSAApplyMethod(t *testing.T) {
+	assert.Equal(t, release.ApplyMethodClientSideApply, determineReleaseSSApplyMethod(false))
+	assert.Equal(t, release.ApplyMethodServerSideApply, determineReleaseSSApplyMethod(true))
+}

pkg/action/get_metadata.go

@@ -47,6 +47,7 @@ type Metadata struct {
 	Revision     int                 `json:"revision" yaml:"revision"`
 	Status       string              `json:"status" yaml:"status"`
 	DeployedAt   string              `json:"deployedAt" yaml:"deployedAt"`
+	ApplyMethod  string              `json:"applyMethod,omitempty" yaml:"applyMethod,omitempty"`
 }
 
 // NewGetMetadata creates a new GetMetadata object with the given configuration.
@@ -79,6 +80,7 @@ func (g *GetMetadata) Run(name string) (*Metadata, error) {
 		Revision:     rel.Version,
 		Status:       rel.Info.Status.String(),
 		DeployedAt:   rel.Info.LastDeployed.Format(time.RFC3339),
+		ApplyMethod:  rel.ApplyMethod,
 	}, nil
 }
 

pkg/action/hooks.go

@@ -33,7 +33,7 @@ import (
 )
 
 // execHook executes all of the hooks for the given hook event.
-func (cfg *Configuration) execHook(rl *release.Release, hook release.HookEvent, waitStrategy kube.WaitStrategy, timeout time.Duration) error {
+func (cfg *Configuration) execHook(rl *release.Release, hook release.HookEvent, waitStrategy kube.WaitStrategy, timeout time.Duration, serverSideApply bool) error {
 	executingHooks := []*release.Hook{}
 
 	for _, h := range rl.Hooks {
@@ -75,7 +75,7 @@ func (cfg *Configuration) execHook(rl *release.Release, hook release.HookEvent,
 		// Create hook resources
 		if _, err := cfg.KubeClient.Create(
 			resources,
-			kube.ClientCreateOptionServerSideApply(false, false)); err != nil {
+			kube.ClientCreateOptionServerSideApply(serverSideApply, false)); err != nil {
 			h.LastRun.CompletedAt = helmtime.Now()
 			h.LastRun.Phase = release.HookPhaseFailed
 			return fmt.Errorf("warning: Hook %s %s failed: %w", hook, h.Path, err)

pkg/action/hooks_test.go

@@ -385,7 +385,8 @@ data:
 				Capabilities: chartutil.DefaultCapabilities,
 			}
 
-			err := configuration.execHook(&tc.inputRelease, hookEvent, kube.StatusWatcherStrategy, 600)
+			serverSideApply := true
+			err := configuration.execHook(&tc.inputRelease, hookEvent, kube.StatusWatcherStrategy, 600, serverSideApply)
 
 			if !reflect.DeepEqual(kubeClient.deleteRecord, tc.expectedDeleteRecord) {
 				t.Fatalf("Got unexpected delete record, expected: %#v, but got: %#v", kubeClient.deleteRecord, tc.expectedDeleteRecord)

pkg/action/install.go

@@ -76,6 +76,12 @@ type Install struct {
 	//
 	// This should be used with caution.
 	ForceReplace bool
+	// ForceConflicts causes server-side apply to force conflicts ("Overwrite value, become sole manager")
+	// see: https://kubernetes.io/docs/reference/using-api/server-side-apply/#conflicts
+	ForceConflicts bool
+	// ServerSideApply when true (default) will enable changes to be applied via Kubernetes server-side apply
+	// see: https://kubernetes.io/docs/reference/using-api/server-side-apply/
+	ServerSideApply bool
 	CreateNamespace bool
 	DryRun          bool
 	DryRunOption    string
@@ -146,6 +152,7 @@ type ChartPathOptions struct {
 func NewInstall(cfg *Configuration) *Install {
 	in := &Install{
 		cfg:             cfg,
+		ServerSideApply: true,
 	}
 	in.registryClient = cfg.RegistryClient
 
@@ -175,7 +182,7 @@ func (i *Install) installCRDs(crds []chart.CRD) error {
 		// Send them to Kube
 		if _, err := i.cfg.KubeClient.Create(
 			res,
-			kube.ClientCreateOptionServerSideApply(false, false)); err != nil {
+			kube.ClientCreateOptionServerSideApply(i.ServerSideApply, i.ForceConflicts)); err != nil {
 			// If the error is CRD already exists, continue.
 			if apierrors.IsAlreadyExists(err) {
 				crdName := res[0].Name
@@ -403,7 +410,7 @@ func (i *Install) RunWithContext(ctx context.Context, chrt *chart.Chart, vals ma
 		}
 		if _, err := i.cfg.KubeClient.Create(
 			resourceList,
-			kube.ClientCreateOptionServerSideApply(false, false)); err != nil && !apierrors.IsAlreadyExists(err) {
+			kube.ClientCreateOptionServerSideApply(i.ServerSideApply, false)); err != nil && !apierrors.IsAlreadyExists(err) {
 			return nil, err
 		}
 	}
@@ -415,8 +422,7 @@ func (i *Install) RunWithContext(ctx context.Context, chrt *chart.Chart, vals ma
 		}
 	}
 
-	// Store the release in history before continuing (new in Helm 3). We always know
+	// Store the release in history before continuing. We always know that this is a create operation
-	// that this is a create operation.
 	if err := i.cfg.Releases.Create(rel); err != nil {
 		// We could try to recover gracefully here, but since nothing has been installed
 		// yet, this is probably safer than trying to continue when we know storage is
@@ -463,7 +469,7 @@ func (i *Install) performInstall(rel *release.Release, toBeAdopted kube.Resource
 	var err error
 	// pre-install hooks
 	if !i.DisableHooks {
-		if err := i.cfg.execHook(rel, release.HookPreInstall, i.WaitStrategy, i.Timeout); err != nil {
+		if err := i.cfg.execHook(rel, release.HookPreInstall, i.WaitStrategy, i.Timeout, i.ServerSideApply); err != nil {
 			return rel, fmt.Errorf("failed pre-install: %s", err)
 		}
 	}
@@ -474,15 +480,15 @@ func (i *Install) performInstall(rel *release.Release, toBeAdopted kube.Resource
 	if len(toBeAdopted) == 0 && len(resources) > 0 {
 		_, err = i.cfg.KubeClient.Create(
 			resources,
-			kube.ClientCreateOptionServerSideApply(false, false))
+			kube.ClientCreateOptionServerSideApply(i.ServerSideApply, false))
 	} else if len(resources) > 0 {
-		updateThreeWayMergeForUnstructured := i.TakeOwnership
+		useUpdateThreeWayMergeForUnstructured := i.TakeOwnership && !i.ServerSideApply // Use three-way merge when taking ownership (and not using server-side apply)
 		_, err = i.cfg.KubeClient.Update(
 			toBeAdopted,
 			resources,
-			kube.ClientUpdateOptionServerSideApply(false, false),
+			kube.ClientUpdateOptionForceReplace(i.ForceReplace),
-			kube.ClientUpdateOptionThreeWayMergeForUnstructured(updateThreeWayMergeForUnstructured),
+			kube.ClientUpdateOptionServerSideApply(i.ServerSideApply, i.ForceConflicts),
-			kube.ClientUpdateOptionForceReplace(i.ForceReplace))
+			kube.ClientUpdateOptionThreeWayMergeForUnstructured(useUpdateThreeWayMergeForUnstructured))
 	}
 	if err != nil {
 		return rel, err
@@ -503,7 +509,7 @@ func (i *Install) performInstall(rel *release.Release, toBeAdopted kube.Resource
 	}
 
 	if !i.DisableHooks {
-		if err := i.cfg.execHook(rel, release.HookPostInstall, i.WaitStrategy, i.Timeout); err != nil {
+		if err := i.cfg.execHook(rel, release.HookPostInstall, i.WaitStrategy, i.Timeout, i.ServerSideApply); err != nil {
 			return rel, fmt.Errorf("failed post-install: %s", err)
 		}
 	}
@@ -580,7 +586,8 @@ func (i *Install) availableName() error {
 // createRelease creates a new release object
 func (i *Install) createRelease(chrt *chart.Chart, rawVals map[string]interface{}, labels map[string]string) *release.Release {
 	ts := i.cfg.Now()
-	return &release.Release{
+
+	r := &release.Release{
 		Name:      i.ReleaseName,
 		Namespace: i.Namespace,
 		Chart:     chrt,
@@ -592,7 +599,10 @@ func (i *Install) createRelease(chrt *chart.Chart, rawVals map[string]interface{
 		},
 		Version:     1,
 		Labels:      labels,
+		ApplyMethod: string(determineReleaseSSApplyMethod(i.ServerSideApply)),
 	}
+
+	return r
 }
 
 // recordRelease with an update operation in case reuse has been set.

pkg/action/release_testing.go

@@ -96,7 +96,8 @@ func (r *ReleaseTesting) Run(name string) (*release.Release, error) {
 		rel.Hooks = executingHooks
 	}
 
-	if err := r.cfg.execHook(rel, release.HookTest, kube.StatusWatcherStrategy, r.Timeout); err != nil {
+	serverSideApply := rel.ApplyMethod == string(release.ApplyMethodServerSideApply)
+	if err := r.cfg.execHook(rel, release.HookTest, kube.StatusWatcherStrategy, r.Timeout, serverSideApply); err != nil {
 		rel.Hooks = append(skippedHooks, rel.Hooks...)
 		r.cfg.Releases.Update(rel)
 		return rel, err

pkg/action/rollback.go

@@ -45,6 +45,14 @@ type Rollback struct {
 	//
 	// This should be used with caution.
 	ForceReplace bool
+	// ForceConflicts causes server-side apply to force conflicts ("Overwrite value, become sole manager")
+	// see: https://kubernetes.io/docs/reference/using-api/server-side-apply/#conflicts
+	ForceConflicts bool
+	// ServerSideApply enables changes to be applied via Kubernetes server-side apply
+	// Can be the string: "true", "false" or "auto"
+	// When "auto", sever-side usage will be based upon the releases previous usage
+	// see: https://kubernetes.io/docs/reference/using-api/server-side-apply/
+	ServerSideApply string
 	CleanupOnFail   bool
 	MaxHistory      int // MaxHistory limits the maximum number of revisions saved per release
 }
@@ -65,7 +73,7 @@ func (r *Rollback) Run(name string) error {
 	r.cfg.Releases.MaxHistory = r.MaxHistory
 
 	slog.Debug("preparing rollback", "name", name)
-	currentRelease, targetRelease, err := r.prepareRollback(name)
+	currentRelease, targetRelease, serverSideApply, err := r.prepareRollback(name)
 	if err != nil {
 		return err
 	}
@@ -78,7 +86,7 @@ func (r *Rollback) Run(name string) error {
 	}
 
 	slog.Debug("performing rollback", "name", name)
-	if _, err := r.performRollback(currentRelease, targetRelease); err != nil {
+	if _, err := r.performRollback(currentRelease, targetRelease, serverSideApply); err != nil {
 		return err
 	}
 
@@ -93,18 +101,18 @@ func (r *Rollback) Run(name string) error {
 
 // prepareRollback finds the previous release and prepares a new release object with
 // the previous release's configuration
-func (r *Rollback) prepareRollback(name string) (*release.Release, *release.Release, error) {
+func (r *Rollback) prepareRollback(name string) (*release.Release, *release.Release, bool, error) {
 	if err := chartutil.ValidateReleaseName(name); err != nil {
-		return nil, nil, fmt.Errorf("prepareRollback: Release name is invalid: %s", name)
+		return nil, nil, false, fmt.Errorf("prepareRollback: Release name is invalid: %s", name)
 	}
 
 	if r.Version < 0 {
-		return nil, nil, errInvalidRevision
+		return nil, nil, false, errInvalidRevision
 	}
 
 	currentRelease, err := r.cfg.Releases.Last(name)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, false, err
 	}
 
 	previousVersion := r.Version
@@ -114,7 +122,7 @@ func (r *Rollback) prepareRollback(name string) (*release.Release, *release.Rele
 
 	historyReleases, err := r.cfg.Releases.History(name)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, false, err
 	}
 
 	// Check if the history version to be rolled back exists
@@ -127,14 +135,19 @@ func (r *Rollback) prepareRollback(name string) (*release.Release, *release.Rele
 		}
 	}
 	if !previousVersionExist {
-		return nil, nil, fmt.Errorf("release has no %d version", previousVersion)
+		return nil, nil, false, fmt.Errorf("release has no %d version", previousVersion)
 	}
 
 	slog.Debug("rolling back", "name", name, "currentVersion", currentRelease.Version, "targetVersion", previousVersion)
 
 	previousRelease, err := r.cfg.Releases.Get(name, previousVersion)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, false, err
+	}
+
+	serverSideApply, err := getUpgradeServerSideValue(r.ServerSideApply, previousRelease.ApplyMethod)
+	if err != nil {
+		return nil, nil, false, err
 	}
 
 	// Store a new release object with previous release's configuration
@@ -156,12 +169,13 @@ func (r *Rollback) prepareRollback(name string) (*release.Release, *release.Rele
 		Labels:      previousRelease.Labels,
 		Manifest:    previousRelease.Manifest,
 		Hooks:       previousRelease.Hooks,
+		ApplyMethod: string(determineReleaseSSApplyMethod(serverSideApply)),
 	}
 
-	return currentRelease, targetRelease, nil
+	return currentRelease, targetRelease, serverSideApply, nil
 }
 
-func (r *Rollback) performRollback(currentRelease, targetRelease *release.Release) (*release.Release, error) {
+func (r *Rollback) performRollback(currentRelease, targetRelease *release.Release, serverSideApply bool) (*release.Release, error) {
 	if r.DryRun {
 		slog.Debug("dry run", "name", targetRelease.Name)
 		return targetRelease, nil
@@ -177,15 +191,16 @@ func (r *Rollback) performRollback(currentRelease, targetRelease *release.Releas
 	}
 
 	// pre-rollback hooks
+
 	if !r.DisableHooks {
-		if err := r.cfg.execHook(targetRelease, release.HookPreRollback, r.WaitStrategy, r.Timeout); err != nil {
+		if err := r.cfg.execHook(targetRelease, release.HookPreRollback, r.WaitStrategy, r.Timeout, serverSideApply); err != nil {
 			return targetRelease, err
 		}
 	} else {
 		slog.Debug("rollback hooks disabled", "name", targetRelease.Name)
 	}
 
-	// It is safe to use "force" here because these are resources currently rendered by the chart.
+	// It is safe to use "forceOwnership" here because these are resources currently rendered by the chart.
 	err = target.Visit(setMetadataVisitor(targetRelease.Name, targetRelease.Namespace, true))
 	if err != nil {
 		return targetRelease, fmt.Errorf("unable to set metadata visitor from target release: %w", err)
@@ -193,8 +208,9 @@ func (r *Rollback) performRollback(currentRelease, targetRelease *release.Releas
 	results, err := r.cfg.KubeClient.Update(
 		current,
 		target,
-		kube.ClientUpdateOptionServerSideApply(false, false),
+		kube.ClientUpdateOptionForceReplace(r.ForceReplace),
-		kube.ClientUpdateOptionForceReplace(r.ForceReplace))
+		kube.ClientUpdateOptionServerSideApply(serverSideApply, r.ForceConflicts),
+		kube.ClientUpdateOptionThreeWayMergeForUnstructured(false))
 
 	if err != nil {
 		msg := fmt.Sprintf("Rollback %q failed: %s", targetRelease.Name, err)
@@ -239,7 +255,7 @@ func (r *Rollback) performRollback(currentRelease, targetRelease *release.Releas
 
 	// post-rollback hooks
 	if !r.DisableHooks {
-		if err := r.cfg.execHook(targetRelease, release.HookPostRollback, r.WaitStrategy, r.Timeout); err != nil {
+		if err := r.cfg.execHook(targetRelease, release.HookPostRollback, r.WaitStrategy, r.Timeout, serverSideApply); err != nil {
 			return targetRelease, err
 		}
 	}

pkg/action/uninstall.go

@@ -115,7 +115,8 @@ func (u *Uninstall) Run(name string) (*release.UninstallReleaseResponse, error)
 	res := &release.UninstallReleaseResponse{Release: rel}
 
 	if !u.DisableHooks {
-		if err := u.cfg.execHook(rel, release.HookPreDelete, u.WaitStrategy, u.Timeout); err != nil {
+		serverSideApply := true
+		if err := u.cfg.execHook(rel, release.HookPreDelete, u.WaitStrategy, u.Timeout, serverSideApply); err != nil {
 			return res, err
 		}
 	} else {
@@ -144,7 +145,8 @@ func (u *Uninstall) Run(name string) (*release.UninstallReleaseResponse, error)
 	}
 
 	if !u.DisableHooks {
-		if err := u.cfg.execHook(rel, release.HookPostDelete, u.WaitStrategy, u.Timeout); err != nil {
+		serverSideApply := true
+		if err := u.cfg.execHook(rel, release.HookPostDelete, u.WaitStrategy, u.Timeout, serverSideApply); err != nil {
 			errs = append(errs, err)
 		}
 	}
@@ -243,6 +245,7 @@ func (u *Uninstall) deleteRelease(rel *release.Release) (kube.ResourceList, stri
 	if err != nil {
 		return nil, "", []error{fmt.Errorf("unable to build kubernetes objects for delete: %w", err)}
 	}
+	if len(resources) > 0 {
 		if len(resources) > 0 {
 			if kubeClient, ok := u.cfg.KubeClient.(kube.InterfaceDeletionPropagation); ok {
 				_, errs = kubeClient.DeleteWithPropagationPolicy(resources, parseCascadingFlag(u.DeletionPropagation))
@@ -250,6 +253,7 @@ func (u *Uninstall) deleteRelease(rel *release.Release) (kube.ResourceList, stri
 			}
 			_, errs = u.cfg.KubeClient.Delete(resources)
 		}
+	}
 	return resources, kept, errs
 }
 

pkg/action/uninstall_test.go

@@ -21,6 +21,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"helm.sh/helm/v4/pkg/kube"
 	kubefake "helm.sh/helm/v4/pkg/kube/fake"
@@ -147,6 +148,6 @@ func TestUninstallRelease_Cascade(t *testing.T) {
 	failer.BuildDummy = true
 	unAction.cfg.KubeClient = failer
 	_, err := unAction.Run(rel.Name)
-	is.Error(err)
+	require.Error(t, err)
 	is.Contains(err.Error(), "failed to delete release: come-fail-away")
 }

pkg/action/upgrade.go

@@ -81,6 +81,14 @@ type Upgrade struct {
 	//
 	// This should be used with caution.
 	ForceReplace bool
+	// ForceConflicts causes server-side apply to force conflicts ("Overwrite value, become sole manager")
+	// see: https://kubernetes.io/docs/reference/using-api/server-side-apply/#conflicts
+	ForceConflicts bool
+	// ServerSideApply enables changes to be applied via Kubernetes server-side apply
+	// Can be the string: "true", "false" or "auto"
+	// When "auto", sever-side usage will be based upon the releases previous usage
+	// see: https://kubernetes.io/docs/reference/using-api/server-side-apply/
+	ServerSideApply string
 	// ResetValues will reset the values to the chart's built-ins rather than merging with existing.
 	ResetValues bool
 	// ReuseValues will reuse the user's last supplied values.
@@ -128,6 +136,7 @@ type resultMessage struct {
 func NewUpgrade(cfg *Configuration) *Upgrade {
 	up := &Upgrade{
 		cfg:             cfg,
+		ServerSideApply: "auto",
 	}
 	up.registryClient = cfg.RegistryClient
 
@@ -162,7 +171,7 @@ func (u *Upgrade) RunWithContext(ctx context.Context, name string, chart *chart.
 	}
 
 	slog.Debug("preparing upgrade", "name", name)
-	currentRelease, upgradedRelease, err := u.prepareUpgrade(name, chart, vals)
+	currentRelease, upgradedRelease, serverSideApply, err := u.prepareUpgrade(name, chart, vals)
 	if err != nil {
 		return nil, err
 	}
@@ -170,7 +179,7 @@ func (u *Upgrade) RunWithContext(ctx context.Context, name string, chart *chart.
 	u.cfg.Releases.MaxHistory = u.MaxHistory
 
 	slog.Debug("performing update", "name", name)
-	res, err := u.performUpgrade(ctx, currentRelease, upgradedRelease)
+	res, err := u.performUpgrade(ctx, currentRelease, upgradedRelease, serverSideApply)
 	if err != nil {
 		return res, err
 	}
@@ -195,14 +204,14 @@ func (u *Upgrade) isDryRun() bool {
 }
 
 // prepareUpgrade builds an upgraded release for an upgrade operation.
-func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[string]interface{}) (*release.Release, *release.Release, error) {
+func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[string]interface{}) (*release.Release, *release.Release, bool, error) {
 	if chart == nil {
-		return nil, nil, errMissingChart
+		return nil, nil, false, errMissingChart
 	}
 
 	// HideSecret must be used with dry run. Otherwise, return an error.
 	if !u.isDryRun() && u.HideSecret {
-		return nil, nil, errors.New("hiding Kubernetes secrets requires a dry-run mode")
+		return nil, nil, false, errors.New("hiding Kubernetes secrets requires a dry-run mode")
 	}
 
 	// finds the last non-deleted release with the given name
@@ -210,14 +219,14 @@ func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[strin
 	if err != nil {
 		// to keep existing behavior of returning the "%q has no deployed releases" error when an existing release does not exist
 		if errors.Is(err, driver.ErrReleaseNotFound) {
-			return nil, nil, driver.NewErrNoDeployedReleases(name)
+			return nil, nil, false, driver.NewErrNoDeployedReleases(name)
 		}
-		return nil, nil, err
+		return nil, nil, false, err
 	}
 
 	// Concurrent `helm upgrade`s will either fail here with `errPending` or when creating the release with "already exists". This should act as a pessimistic lock.
 	if lastRelease.Info.Status.IsPending() {
-		return nil, nil, errPending
+		return nil, nil, false, errPending
 	}
 
 	var currentRelease *release.Release
@@ -232,7 +241,7 @@ func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[strin
 				(lastRelease.Info.Status == release.StatusFailed || lastRelease.Info.Status == release.StatusSuperseded) {
 				currentRelease = lastRelease
 			} else {
-				return nil, nil, err
+				return nil, nil, false, err
 			}
 		}
 	}
@@ -240,11 +249,11 @@ func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[strin
 	// determine if values will be reused
 	vals, err = u.reuseValues(chart, currentRelease, vals)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, false, err
 	}
 
 	if err := chartutil.ProcessDependencies(chart, vals); err != nil {
-		return nil, nil, err
+		return nil, nil, false, err
 	}
 
 	// Increment revision count. This is passed to templates, and also stored on
@@ -260,11 +269,11 @@ func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[strin
 
 	caps, err := u.cfg.getCapabilities()
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, false, err
 	}
 	valuesToRender, err := chartutil.ToRenderValuesWithSchemaValidation(chart, vals, options, caps, u.SkipSchemaValidation)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, false, err
 	}
 
 	// Determine whether or not to interact with remote
@@ -275,13 +284,20 @@ func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[strin
 
 	hooks, manifestDoc, notesTxt, err := u.cfg.renderResources(chart, valuesToRender, "", "", u.SubNotes, false, false, u.PostRenderer, interactWithRemote, u.EnableDNS, u.HideSecret)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, false, err
 	}
 
 	if driver.ContainsSystemLabels(u.Labels) {
-		return nil, nil, fmt.Errorf("user supplied labels contains system reserved label name. System labels: %+v", driver.GetSystemLabels())
+		return nil, nil, false, fmt.Errorf("user supplied labels contains system reserved label name. System labels: %+v", driver.GetSystemLabels())
 	}
 
+	serverSideApply, err := getUpgradeServerSideValue(u.ServerSideApply, lastRelease.ApplyMethod)
+	if err != nil {
+		return nil, nil, false, err
+	}
+
+	slog.Debug("determined release apply method", slog.Bool("server_side_apply", serverSideApply), slog.String("previous_release_apply_method", lastRelease.ApplyMethod))
+
 	// Store an upgraded release.
 	upgradedRelease := &release.Release{
 		Name:      name,
@@ -298,16 +314,17 @@ func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[strin
 		Manifest:    manifestDoc.String(),
 		Hooks:       hooks,
 		Labels:      mergeCustomLabels(lastRelease.Labels, u.Labels),
+		ApplyMethod: string(determineReleaseSSApplyMethod(serverSideApply)),
 	}
 
 	if len(notesTxt) > 0 {
 		upgradedRelease.Info.Notes = notesTxt
 	}
 	err = validateManifest(u.cfg.KubeClient, manifestDoc.Bytes(), !u.DisableOpenAPIValidation)
-	return currentRelease, upgradedRelease, err
+	return currentRelease, upgradedRelease, serverSideApply, err
 }
 
-func (u *Upgrade) performUpgrade(ctx context.Context, originalRelease, upgradedRelease *release.Release) (*release.Release, error) {
+func (u *Upgrade) performUpgrade(ctx context.Context, originalRelease, upgradedRelease *release.Release, serverSideApply bool) (*release.Release, error) {
 	current, err := u.cfg.KubeClient.Build(bytes.NewBufferString(originalRelease.Manifest), false)
 	if err != nil {
 		// Checking for removed Kubernetes API error so can provide a more informative error message to the user
@@ -380,7 +397,7 @@ func (u *Upgrade) performUpgrade(ctx context.Context, originalRelease, upgradedR
 	ctxChan := make(chan resultMessage)
 	doneChan := make(chan interface{})
 	defer close(doneChan)
-	go u.releasingUpgrade(rChan, upgradedRelease, current, target, originalRelease)
+	go u.releasingUpgrade(rChan, upgradedRelease, current, target, originalRelease, serverSideApply)
 	go u.handleContext(ctx, doneChan, ctxChan, upgradedRelease)
 	select {
 	case result := <-rChan:
@@ -414,11 +431,11 @@ func (u *Upgrade) handleContext(ctx context.Context, done chan interface{}, c ch
 		return
 	}
 }
-func (u *Upgrade) releasingUpgrade(c chan<- resultMessage, upgradedRelease *release.Release, current kube.ResourceList, target kube.ResourceList, originalRelease *release.Release) {
+func (u *Upgrade) releasingUpgrade(c chan<- resultMessage, upgradedRelease *release.Release, current kube.ResourceList, target kube.ResourceList, originalRelease *release.Release, serverSideApply bool) {
 	// pre-upgrade hooks
 
 	if !u.DisableHooks {
-		if err := u.cfg.execHook(upgradedRelease, release.HookPreUpgrade, u.WaitStrategy, u.Timeout); err != nil {
+		if err := u.cfg.execHook(upgradedRelease, release.HookPreUpgrade, u.WaitStrategy, u.Timeout, serverSideApply); err != nil {
 			u.reportToPerformUpgrade(c, upgradedRelease, kube.ResourceList{}, fmt.Errorf("pre-upgrade hooks failed: %s", err))
 			return
 		}
@@ -429,8 +446,8 @@ func (u *Upgrade) releasingUpgrade(c chan<- resultMessage, upgradedRelease *rele
 	results, err := u.cfg.KubeClient.Update(
 		current,
 		target,
-		kube.ClientUpdateOptionServerSideApply(false, false),
+		kube.ClientUpdateOptionForceReplace(u.ForceReplace),
-		kube.ClientUpdateOptionForceReplace(u.ForceReplace))
+		kube.ClientUpdateOptionServerSideApply(serverSideApply, u.ForceConflicts))
 	if err != nil {
 		u.cfg.recordRelease(originalRelease)
 		u.reportToPerformUpgrade(c, upgradedRelease, results.Created, err)
@@ -459,7 +476,7 @@ func (u *Upgrade) releasingUpgrade(c chan<- resultMessage, upgradedRelease *rele
 
 	// post-upgrade hooks
 	if !u.DisableHooks {
-		if err := u.cfg.execHook(upgradedRelease, release.HookPostUpgrade, u.WaitStrategy, u.Timeout); err != nil {
+		if err := u.cfg.execHook(upgradedRelease, release.HookPostUpgrade, u.WaitStrategy, u.Timeout, serverSideApply); err != nil {
 			u.reportToPerformUpgrade(c, upgradedRelease, results.Created, fmt.Errorf("post-upgrade hooks failed: %s", err))
 			return
 		}
@@ -530,6 +547,8 @@ func (u *Upgrade) failRelease(rel *release.Release, created kube.ResourceList, e
 		rollin.WaitForJobs = u.WaitForJobs
 		rollin.DisableHooks = u.DisableHooks
 		rollin.ForceReplace = u.ForceReplace
+		rollin.ForceConflicts = u.ForceConflicts
+		rollin.ServerSideApply = u.ServerSideApply
 		rollin.Timeout = u.Timeout
 		if rollErr := rollin.Run(rel.Name); rollErr != nil {
 			return rel, fmt.Errorf("an error occurred while rolling back the release. original upgrade error: %w: %w", err, rollErr)
@@ -607,3 +626,16 @@ func mergeCustomLabels(current, desired map[string]string) map[string]string {
 	}
 	return labels
 }
+
+func getUpgradeServerSideValue(serverSideOption string, releaseApplyMethod string) (bool, error) {
+	switch serverSideOption {
+	case "auto":
+		return releaseApplyMethod == "ssa", nil
+	case "false":
+		return false, nil
+	case "true":
+		return true, nil
+	default:
+		return false, fmt.Errorf("invalid/unknown release server-side apply method: %s", serverSideOption)
+	}
+}

pkg/action/upgrade_test.go

@@ -583,3 +583,109 @@ func TestUpgradeRelease_DryRun(t *testing.T) {
 	done()
 	req.Error(err)
 }
+
+func TestGetUpgradeServerSideValue(t *testing.T) {
+	tests := []struct {
+		name                    string
+		actionServerSideOption  string
+		releaseApplyMethod      string
+		expectedServerSideApply bool
+	}{
+		{
+			name:                    "action ssa auto / release csa",
+			actionServerSideOption:  "auto",
+			releaseApplyMethod:      "csa",
+			expectedServerSideApply: false,
+		},
+		{
+			name:                    "action ssa auto / release ssa",
+			actionServerSideOption:  "auto",
+			releaseApplyMethod:      "ssa",
+			expectedServerSideApply: true,
+		},
+		{
+			name:                    "action ssa auto / release empty",
+			actionServerSideOption:  "auto",
+			releaseApplyMethod:      "",
+			expectedServerSideApply: false,
+		},
+		{
+			name:                    "action ssa true / release csa",
+			actionServerSideOption:  "true",
+			releaseApplyMethod:      "csa",
+			expectedServerSideApply: true,
+		},
+		{
+			name:                    "action ssa true / release ssa",
+			actionServerSideOption:  "true",
+			releaseApplyMethod:      "ssa",
+			expectedServerSideApply: true,
+		},
+		{
+			name:                    "action ssa true / release 'unknown'",
+			actionServerSideOption:  "true",
+			releaseApplyMethod:      "foo",
+			expectedServerSideApply: true,
+		},
+		{
+			name:                    "action ssa true / release empty",
+			actionServerSideOption:  "true",
+			releaseApplyMethod:      "",
+			expectedServerSideApply: true,
+		},
+		{
+			name:                    "action ssa false / release csa",
+			actionServerSideOption:  "false",
+			releaseApplyMethod:      "ssa",
+			expectedServerSideApply: false,
+		},
+		{
+			name:                    "action ssa false / release ssa",
+			actionServerSideOption:  "false",
+			releaseApplyMethod:      "ssa",
+			expectedServerSideApply: false,
+		},
+		{
+			name:                    "action ssa false / release 'unknown'",
+			actionServerSideOption:  "false",
+			releaseApplyMethod:      "foo",
+			expectedServerSideApply: false,
+		},
+		{
+			name:                    "action ssa false / release empty",
+			actionServerSideOption:  "false",
+			releaseApplyMethod:      "ssa",
+			expectedServerSideApply: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			serverSideApply, err := getUpgradeServerSideValue(tt.actionServerSideOption, tt.releaseApplyMethod)
+			assert.Nil(t, err)
+			assert.Equal(t, tt.expectedServerSideApply, serverSideApply)
+		})
+	}
+
+	testsError := []struct {
+		name                   string
+		actionServerSideOption string
+		releaseApplyMethod     string
+		expectedErrorMsg       string
+	}{
+		{
+			name:                   "action invalid option",
+			actionServerSideOption: "invalid",
+			releaseApplyMethod:     "ssa",
+			expectedErrorMsg:       "invalid/unknown release server-side apply method: invalid",
+		},
+	}
+
+	for _, tt := range testsError {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := getUpgradeServerSideValue(tt.actionServerSideOption, tt.releaseApplyMethod)
+			assert.ErrorContains(t, err, tt.expectedErrorMsg)
+		})
+	}
+
+}

pkg/cmd/get_metadata.go

@@ -27,6 +27,8 @@ import (
 	"helm.sh/helm/v4/pkg/action"
 	"helm.sh/helm/v4/pkg/cli/output"
 	"helm.sh/helm/v4/pkg/cmd/require"
+
+	release "helm.sh/helm/v4/pkg/release/v1"
 )
 
 type metadataWriter struct {
@@ -75,6 +77,20 @@ func newGetMetadataCmd(cfg *action.Configuration, out io.Writer) *cobra.Command
 }
 
 func (w metadataWriter) WriteTable(out io.Writer) error {
+
+	formatApplyMethod := func(applyMethod string) string {
+		switch applyMethod {
+		case "":
+			return "client-side apply (defaulted)"
+		case string(release.ApplyMethodClientSideApply):
+			return "client-side apply"
+		case string(release.ApplyMethodServerSideApply):
+			return "server-side apply"
+		default:
+			return fmt.Sprintf("unknown (%q)", applyMethod)
+		}
+	}
+
 	_, _ = fmt.Fprintf(out, "NAME: %v\n", w.metadata.Name)
 	_, _ = fmt.Fprintf(out, "CHART: %v\n", w.metadata.Chart)
 	_, _ = fmt.Fprintf(out, "VERSION: %v\n", w.metadata.Version)
@@ -86,6 +102,7 @@ func (w metadataWriter) WriteTable(out io.Writer) error {
 	_, _ = fmt.Fprintf(out, "REVISION: %v\n", w.metadata.Revision)
 	_, _ = fmt.Fprintf(out, "STATUS: %v\n", w.metadata.Status)
 	_, _ = fmt.Fprintf(out, "DEPLOYED_AT: %v\n", w.metadata.DeployedAt)
+	_, _ = fmt.Fprintf(out, "APPLY_METHOD: %v\n", formatApplyMethod(w.metadata.ApplyMethod))
 
 	return nil
 }

pkg/cmd/install.go

@@ -196,6 +196,8 @@ func addInstallFlags(cmd *cobra.Command, f *pflag.FlagSet, client *action.Instal
 	f.BoolVar(&client.ForceReplace, "force-replace", false, "force resource updates by replacement")
 	f.BoolVar(&client.ForceReplace, "force", false, "deprecated")
 	f.MarkDeprecated("force", "use --force-replace instead")
+	f.BoolVar(&client.ForceConflicts, "force-conflicts", false, "if set server-side apply will force changes against conflicts")
+	f.BoolVar(&client.ServerSideApply, "server-side", true, "object updates run in the server instead of the client")
 	f.BoolVar(&client.DisableHooks, "no-hooks", false, "prevent hooks from running during install")
 	f.BoolVar(&client.Replace, "replace", false, "reuse the given name, only if that name is a deleted release which remains in the history. This is unsafe in production")
 	f.DurationVar(&client.Timeout, "timeout", 300*time.Second, "time to wait for any individual Kubernetes operation (like Jobs for hooks)")
@@ -217,6 +219,8 @@ func addInstallFlags(cmd *cobra.Command, f *pflag.FlagSet, client *action.Instal
 	addValueOptionsFlags(f, valueOpts)
 	addChartPathOptionsFlags(f, &client.ChartPathOptions)
 	AddWaitFlag(cmd, &client.WaitStrategy)
+	cmd.MarkFlagsMutuallyExclusive("force-replace", "force-conflicts")
+	cmd.MarkFlagsMutuallyExclusive("force", "force-conflicts")
 
 	err := cmd.RegisterFlagCompletionFunc("version", func(_ *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 		requiredArgs := 2

pkg/cmd/rollback.go

@@ -80,12 +80,16 @@ func newRollbackCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	f.BoolVar(&client.ForceReplace, "force-replace", false, "force resource updates by replacement")
 	f.BoolVar(&client.ForceReplace, "force", false, "deprecated")
 	f.MarkDeprecated("force", "use --force-replace instead")
+	f.BoolVar(&client.ForceConflicts, "force-conflicts", false, "if set server-side apply will force changes against conflicts")
+	f.StringVar(&client.ServerSideApply, "server-side", "auto", "must be \"true\", \"false\" or \"auto\". Object updates run in the server instead of the client (\"auto\" defaults the value from the previous chart release's method)")
 	f.BoolVar(&client.DisableHooks, "no-hooks", false, "prevent hooks from running during rollback")
 	f.DurationVar(&client.Timeout, "timeout", 300*time.Second, "time to wait for any individual Kubernetes operation (like Jobs for hooks)")
 	f.BoolVar(&client.WaitForJobs, "wait-for-jobs", false, "if set and --wait enabled, will wait until all Jobs have been completed before marking the release as successful. It will wait for as long as --timeout")
 	f.BoolVar(&client.CleanupOnFail, "cleanup-on-fail", false, "allow deletion of new resources created in this rollback when rollback fails")
 	f.IntVar(&client.MaxHistory, "history-max", settings.MaxHistory, "limit the maximum number of revisions saved per release. Use 0 for no limit")
 	AddWaitFlag(cmd, &client.WaitStrategy)
+	cmd.MarkFlagsMutuallyExclusive("force-replace", "force-conflicts")
+	cmd.MarkFlagsMutuallyExclusive("force", "force-conflicts")
 
 	return cmd
 }

pkg/cmd/testdata/output/get-metadata.txt

@@ -9,3 +9,4 @@ NAMESPACE: default
 REVISION: 1
 STATUS: deployed
 DEPLOYED_AT: 1977-09-02T22:04:05Z
+APPLY_METHOD: client-side apply (defaulted)

pkg/cmd/upgrade.go

@@ -273,6 +273,8 @@ func newUpgradeCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	f.BoolVar(&client.ForceReplace, "force-replace", false, "force resource updates by replacement")
 	f.BoolVar(&client.ForceReplace, "force", false, "deprecated")
 	f.MarkDeprecated("force", "use --force-replace instead")
+	f.BoolVar(&client.ForceConflicts, "force-conflicts", false, "if set server-side apply will force changes against conflicts")
+	f.StringVar(&client.ServerSideApply, "server-side", "auto", "must be \"true\", \"false\" or \"auto\". Object updates run in the server instead of the client (\"auto\" defaults the value from the previous chart release's method)")
 	f.BoolVar(&client.DisableHooks, "no-hooks", false, "disable pre/post upgrade hooks")
 	f.BoolVar(&client.DisableOpenAPIValidation, "disable-openapi-validation", false, "if set, the upgrade process will not validate rendered templates against the Kubernetes OpenAPI Schema")
 	f.BoolVar(&client.SkipCRDs, "skip-crds", false, "if set, no CRDs will be installed when an upgrade is performed with install flag enabled. By default, CRDs are installed if not already present, when an upgrade is performed with install flag enabled")
@@ -297,6 +299,8 @@ func newUpgradeCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	bindOutputFlag(cmd, &outfmt)
 	bindPostRenderFlag(cmd, &client.PostRenderer)
 	AddWaitFlag(cmd, &client.WaitStrategy)
+	cmd.MarkFlagsMutuallyExclusive("force-replace", "force-conflicts")
+	cmd.MarkFlagsMutuallyExclusive("force", "force-conflicts")
 
 	err := cmd.RegisterFlagCompletionFunc("version", func(_ *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 		if len(args) != 2 {

pkg/kube/fake/fake.go

@@ -108,6 +108,14 @@ func (f *FailingKubeClient) Delete(resources kube.ResourceList) (*kube.Result, [
 	return f.PrintingKubeClient.Delete(resources)
 }
 
+// DeleteWithPropagationPolicy returns the configured error if set or prints
+func (f *FailingKubeClient) DeleteWithPropagationPolicy(resources kube.ResourceList, policy metav1.DeletionPropagation) (*kube.Result, []error) {
+	if f.DeleteWithPropagationError != nil {
+		return nil, []error{f.DeleteWithPropagationError}
+	}
+	return f.PrintingKubeClient.DeleteWithPropagationPolicy(resources, policy)
+}
+
 // WatchUntilReady returns the configured error if set or prints
 func (f *FailingKubeWaiter) WatchUntilReady(resources kube.ResourceList, d time.Duration) error {
 	if f.watchUntilReadyError != nil {
@@ -146,14 +154,6 @@ func (f *FailingKubeClient) BuildTable(r io.Reader, _ bool) (kube.ResourceList,
 	return f.PrintingKubeClient.BuildTable(r, false)
 }
 
-// DeleteWithPropagationPolicy returns the configured error if set or prints
-func (f *FailingKubeClient) DeleteWithPropagationPolicy(resources kube.ResourceList, policy metav1.DeletionPropagation) (*kube.Result, []error) {
-	if f.DeleteWithPropagationError != nil {
-		return nil, []error{f.DeleteWithPropagationError}
-	}
-	return f.PrintingKubeClient.DeleteWithPropagationPolicy(resources, policy)
-}
-
 func (f *FailingKubeClient) GetWaiter(ws kube.WaitStrategy) (kube.Waiter, error) {
 	waiter, _ := f.PrintingKubeClient.GetWaiter(ws)
 	printingKubeWaiter, _ := waiter.(*PrintingKubeWaiter)

pkg/kube/fake/printer.go

@@ -97,6 +97,17 @@ func (p *PrintingKubeClient) Delete(resources kube.ResourceList) (*kube.Result,
 	return &kube.Result{Deleted: resources}, nil
 }
 
+// DeleteWithPropagationPolicy implements KubeClient delete.
+//
+// It only prints out the content to be deleted.
+func (p *PrintingKubeClient) DeleteWithPropagationPolicy(resources kube.ResourceList, _ metav1.DeletionPropagation) (*kube.Result, []error) {
+	_, err := io.Copy(p.Out, bufferize(resources))
+	if err != nil {
+		return nil, []error{err}
+	}
+	return &kube.Result{Deleted: resources}, nil
+}
+
 // Update implements KubeClient Update.
 func (p *PrintingKubeClient) Update(_, modified kube.ResourceList, _ ...kube.ClientUpdateOption) (*kube.Result, error) {
 	_, err := io.Copy(p.Out, bufferize(modified))
@@ -135,17 +146,6 @@ func (p *PrintingKubeClient) OutputContainerLogsForPodList(_ *v1.PodList, someNa
 	return err
 }
 
-// DeleteWithPropagationPolicy implements KubeClient delete.
-//
-// It only prints out the content to be deleted.
-func (p *PrintingKubeClient) DeleteWithPropagationPolicy(resources kube.ResourceList, _ metav1.DeletionPropagation) (*kube.Result, []error) {
-	_, err := io.Copy(p.Out, bufferize(resources))
-	if err != nil {
-		return nil, []error{err}
-	}
-	return &kube.Result{Deleted: resources}, nil
-}
-
 func (p *PrintingKubeClient) GetWaiter(_ kube.WaitStrategy) (kube.Waiter, error) {
 	return &PrintingKubeWaiter{Out: p.Out, LogOutput: p.LogOutput}, nil
 }

pkg/release/v1/release.go

@@ -19,6 +19,11 @@ import (
 	chart "helm.sh/helm/v4/pkg/chart/v2"
 )
 
+type ApplyMethod string
+
+const ApplyMethodClientSideApply ApplyMethod = "csa"
+const ApplyMethodServerSideApply ApplyMethod = "ssa"
+
 // Release describes a deployment of a chart, together with the chart
 // and the variables used to deploy that chart.
 type Release struct {
@@ -42,6 +47,9 @@ type Release struct {
 	// Labels of the release.
 	// Disabled encoding into Json cause labels are stored in storage driver metadata field.
 	Labels map[string]string `json:"-"`
+	// ApplyMethod stores whether server-side or client-side apply was used for the release
+	// Unset (empty string) should be treated as the default of client-side apply
+	ApplyMethod string `json:"apply_method,omitempty"` // "ssa" | "csa"
 }
 
 // SetStatus is a helper for setting the status on a release.