feat: Automatically enable Helm v3 mode

Runs `helm version` in helmexec.New, and exposes a method on Interface to allow other packages to use the detected version. Preserves compatibility with previous HELMFILE_HELM3 mechanism.

Resolves #923

pkg/app/app_test.go

@@ -1994,6 +1994,9 @@ func (helm *mockHelmExec) Fetch(chart string, flags ...string) error {
 func (helm *mockHelmExec) Lint(name, chart string, flags ...string) error {
 	return nil
 }
+func (helm *mockHelmExec) IsHelm3() bool {
+	return false
+}
 
 func TestTemplate_SingleStateFile(t *testing.T) {
 	files := map[string]string{

pkg/exectest/helm.go

@@ -157,6 +157,10 @@ func (helm *Helm) TemplateRelease(name, chart string, flags ...string) error {
 	return nil
 }
 
+func (helm *Helm) IsHelm3() bool {
+	return false
+}
+
 func (helm *Helm) sync(m *sync.Mutex, f func()) {
 	if m != nil {
 		m.Lock()

pkg/helmexec/exec.go

@@ -20,6 +20,7 @@ type decryptedSecret struct {
 
 type execer struct {
 	helmBinary           string
+	isHelm3              bool
 	runner               Runner
 	logger               *zap.SugaredLogger
 	kubeContext          string
@@ -45,15 +46,31 @@ func NewLogger(writer io.Writer, logLevel string) *zap.SugaredLogger {
 	return zap.New(core).Sugar()
 }
 
+func detectHelm3(helmBinary string, logger *zap.SugaredLogger, runner Runner) bool {
+	// Support explicit opt-in via environment variable
+	if os.Getenv("HELMFILE_HELM3") != "" {
+		return true
+	}
+
+	// Autodetect from `helm verison`
+	bytes, err := runner.Execute(helmBinary, []string{"version", "--client", "--short"}, nil)
+	if err != nil {
+		panic(err)
+	}
+	return strings.HasPrefix(string(bytes), "v3.")
+}
+
 // New for running helm commands
 func New(helmBinary string, logger *zap.SugaredLogger, kubeContext string, runner Runner) *execer {
 	return &execer{
 		helmBinary:       helmBinary,
+		isHelm3:          detectHelm3(helmBinary, logger, runner),
 		logger:           logger,
 		kubeContext:      kubeContext,
 		runner:           runner,
 		decryptedSecrets: make(map[string]*decryptedSecret),
 	}
+
 }
 
 func (helm *execer) SetExtraArgs(args ...string) {
@@ -126,7 +143,7 @@ func (helm *execer) List(context HelmContext, filter string, flags ...string) (s
 	preArgs := context.GetTillerlessArgs(helm.helmBinary)
 	env := context.getTillerlessEnv()
 	var args []string
-	if helm.isHelm3() {
+	if helm.IsHelm3() {
 		args = []string{"list", "--filter", filter}
 	} else {
 		args = []string{"list", filter}
@@ -139,7 +156,7 @@ func (helm *execer) List(context HelmContext, filter string, flags ...string) (s
 	// of the release to exist.
 	//
 	// This fixes it by removing the header from the v3 output, so that the output is formatted the same as that of v2.
-	if helm.isHelm3() {
+	if helm.IsHelm3() {
 		lines := strings.Split(string(out), "\n")
 		lines = lines[1:]
 		out = []byte(strings.Join(lines, "\n"))
@@ -219,7 +236,7 @@ func (helm *execer) DecryptSecret(context HelmContext, name string, flags ...str
 func (helm *execer) TemplateRelease(name string, chart string, flags ...string) error {
 	helm.logger.Infof("Templating release=%v, chart=%v", name, chart)
 	var args []string
-	if helm.isHelm3() {
+	if helm.IsHelm3() {
 		args = []string{"template", name, chart}
 	} else {
 		args = []string{"template", chart, "--name", name}
@@ -286,7 +303,7 @@ func (helm *execer) TestRelease(context HelmContext, name string, flags ...strin
 	preArgs := context.GetTillerlessArgs(helm.helmBinary)
 	env := context.getTillerlessEnv()
 	var args []string
-	if helm.isHelm3() {
+	if helm.IsHelm3() {
 		args = []string{"test", "run", name}
 	} else {
 		args = []string{"test", name}
@@ -323,6 +340,6 @@ func (helm *execer) write(out []byte) {
 	}
 }
 
-func (helm *execer) isHelm3() bool {
-	return os.Getenv("HELMFILE_HELM3") != ""
+func (helm *execer) IsHelm3() bool {
+	return helm.isHelm3
 }

pkg/helmexec/helmexec.go

@@ -19,8 +19,10 @@ type Interface interface {
 	TestRelease(context HelmContext, name string, flags ...string) error
 	List(context HelmContext, filter string, flags ...string) (string, error)
 	DecryptSecret(context HelmContext, name string, flags ...string) (string, error)
+	IsHelm3() bool
 }
 
 type DependencyUpdater interface {
 	UpdateDeps(chart string) error
+	IsHelm3() bool
 }

pkg/state/chart_dependency.go

@@ -280,7 +280,7 @@ func (m *chartDependencyManager) lockFileName() string {
 }
 
 func (m *chartDependencyManager) Update(shell helmexec.DependencyUpdater, wd string, unresolved *UnresolvedDependencies) (*ResolvedDependencies, error) {
-	if isHelm3() {
+	if shell.IsHelm3() {
 		return m.updateHelm3(shell, wd, unresolved)
 	}
 	return m.updateHelm2(shell, wd, unresolved)
@@ -330,7 +330,7 @@ func (m *chartDependencyManager) doUpdate(chartLockFile string, unresolved *Unre
 		return nil, err
 	}
 
-	if isHelm3() && originalLockFileContent != nil {
+	if shell.IsHelm3() && originalLockFileContent != nil {
 		if err := m.writeBytes(filepath.Join(wd, chartLockFile), originalLockFileContent); err != nil {
 			return nil, err
 		}
@@ -357,7 +357,7 @@ func (m *chartDependencyManager) doUpdate(chartLockFile string, unresolved *Unre
 	})
 
 	// Don't update lock file if no dependency updated.
-	if !isHelm3() && originalLockFileContent != nil {
+	if !shell.IsHelm3() && originalLockFileContent != nil {
 		originalLockedReqs := &ChartLockedRequirements{}
 		if err := yaml.Unmarshal(originalLockFileContent, originalLockedReqs); err != nil {
 			return nil, err

pkg/state/state.go

@@ -477,7 +477,7 @@ func (st *HelmState) DeleteReleasesForSync(affectedReleases *AffectedReleases, h
 					relErr = newReleaseError(release, err)
 				} else {
 					var args []string
-					if isHelm3() {
+					if helm.IsHelm3() {
 						args = []string{}
 						if release.Namespace != "" {
 							args = append(args, "--namespace", release.Namespace)
@@ -577,7 +577,7 @@ func (st *HelmState) SyncReleases(affectedReleases *AffectedReleases, helm helme
 						relErr = newReleaseError(release, err)
 					} else if installed {
 						var args []string
-						if isHelm3() {
+						if helm.IsHelm3() {
 							args = []string{}
 						} else {
 							args = []string{"--purge"}
@@ -646,7 +646,7 @@ func (st *HelmState) SyncReleases(affectedReleases *AffectedReleases, helm helme
 
 func (st *HelmState) listReleases(context helmexec.HelmContext, helm helmexec.Interface, release *ReleaseSpec) (string, error) {
 	flags := st.connectionFlags(release)
-	if isHelm3() && release.Namespace != "" {
+	if helm.IsHelm3() && release.Namespace != "" {
 		flags = append(flags, "--namespace", release.Namespace)
 	}
 	return helm.List(context, "^"+release.Name+"$", flags...)
@@ -1161,11 +1161,11 @@ func (st *HelmState) DeleteReleases(affectedReleases *AffectedReleases, helm hel
 		st.ApplyOverrides(&release)
 
 		flags := []string{}
-		if purge && !isHelm3() {
+		if purge && !helm.IsHelm3() {
 			flags = append(flags, "--purge")
 		}
 		flags = st.appendConnectionFlags(flags, &release)
-		if isHelm3() && release.Namespace != "" {
+		if helm.IsHelm3() && release.Namespace != "" {
 			flags = append(flags, "--namespace", release.Namespace)
 		}
 		context := st.createHelmContext(&release, workerIndex)
@@ -1192,7 +1192,7 @@ func (st *HelmState) TestReleases(helm helmexec.Interface, cleanup bool, timeout
 			flags = append(flags, "--cleanup")
 		}
 		duration := strconv.Itoa(timeout)
-		if isHelm3() {
+		if helm.IsHelm3() {
 			duration += "s"
 		}
 		flags = append(flags, "--timeout", duration)
@@ -1202,10 +1202,6 @@ func (st *HelmState) TestReleases(helm helmexec.Interface, cleanup bool, timeout
 	})
 }
 
-func isHelm3() bool {
-	return os.Getenv("HELMFILE_HELM3") != ""
-}
-
 // Clean will remove any generated secrets
 func (st *HelmState) Clean() []error {
 	errs := []error{}
@@ -1532,7 +1528,7 @@ func (st *HelmState) flagsForUpgrade(helm helmexec.Interface, release *ReleaseSp
 	}
 	if timeout != 0 {
 		duration := strconv.Itoa(timeout)
-		if isHelm3() {
+		if helm.IsHelm3() {
 			duration += "s"
 		}
 		flags = append(flags, "--timeout", duration)