feat: Allow overriding chart via flag (#1751)

Adds `--chart` flag for overriding the selected release's chart ad-hoc-ly like `helmfile --chart $CHART template`.
This is handy when e.g. you want to have an ArgoCD application per each release in your helmfile.yaml, while also providing the ability to customize the release's chart without touching helmfile.yaml.

See https://github.com/roboll/helmfile/issues/1690#issuecomment-812321354 for more context.

Closes #1690

main.go

@@ -89,6 +89,10 @@ func main() {
 			Name:  "namespace, n",
 			Usage: "Set namespace. Uses the namespace set in the context by default, and is available in templates as {{ .Namespace }}",
 		},
+		cli.StringFlag{
+			Name:  "chart, c",
+			Usage: "Set chart. Uses the chart set in release by default, and is available in template as {{ .Chart }}",
+		},
 		cli.StringSliceFlag{
 			Name: "selector, l",
 			Usage: `Only run using the releases that match labels. Labels can take the form of foo=bar or foo!=bar.
@@ -776,6 +780,10 @@ func (c configImpl) Namespace() string {
 	return c.c.GlobalString("namespace")
 }
 
+func (c configImpl) Chart() string {
+	return c.c.GlobalString("chart")
+}
+
 func (c configImpl) FileOrDir() string {
 	return c.c.GlobalString("file")
 }

pkg/app/app.go

@@ -30,6 +30,7 @@ type App struct {
 	Logger      *zap.SugaredLogger
 	Env         string
 	Namespace   string
+	Chart       string
 	Selectors   []string
 	Args        string
 	ValuesFiles []string
@@ -72,6 +73,7 @@ func New(conf ConfigProvider) *App {
 		Logger:              conf.Logger(),
 		Env:                 conf.Env(),
 		Namespace:           conf.Namespace(),
+		Chart:               conf.Chart(),
 		Selectors:           conf.Selectors(),
 		Args:                conf.Args(),
 		FileOrDir:           conf.FileOrDir(),
@@ -640,6 +642,7 @@ func (a *App) loadDesiredStateFromYaml(file string, opts ...LoadOpts) (*state.He
 		directoryExistsAt: a.directoryExistsAt,
 		env:               a.Env,
 		namespace:         a.Namespace,
+		chart:             a.Chart,
 		logger:            a.Logger,
 		abs:               a.abs,
 		remote:            a.remote,

pkg/app/config.go

@@ -9,6 +9,7 @@ type ConfigProvider interface {
 	FileOrDir() string
 	KubeContext() string
 	Namespace() string
+	Chart() string
 	Selectors() []string
 	StateValuesSet() map[string]interface{}
 	StateValuesFiles() []string

pkg/app/desired_state_file_loader.go

@@ -25,6 +25,7 @@ type desiredStateLoader struct {
 
 	env       string
 	namespace string
+	chart     string
 
 	readFile          func(string) ([]byte, error)
 	deleteFile        func(string) error
@@ -82,6 +83,13 @@ func (ld *desiredStateLoader) Load(f string, opts LoadOpts) (*state.HelmState, e
 		st.OverrideNamespace = ld.namespace
 	}
 
+	if ld.chart != "" {
+		if st.OverrideChart != "" {
+			return nil, errors.New("err: Cannot use option --chart and set attribute chart.")
+		}
+		st.OverrideChart = ld.chart
+	}
+
 	return st, nil
 }
 

pkg/app/two_pass_renderer.go

@@ -3,11 +3,12 @@ package app
 import (
 	"bytes"
 	"fmt"
+	"strings"
+
 	"github.com/google/go-cmp/cmp"
 	"github.com/roboll/helmfile/pkg/environment"
 	"github.com/roboll/helmfile/pkg/state"
 	"github.com/roboll/helmfile/pkg/tmpl"
-	"strings"
 )
 
 func prependLineNumbers(text string) string {

pkg/event/bus.go

@@ -32,6 +32,7 @@ type Bus struct {
 	BasePath      string
 	StateFilePath string
 	Namespace     string
+	Chart         string
 
 	Env environment.Environment
 

pkg/state/state.go

@@ -54,6 +54,7 @@ type ReleaseSetSpec struct {
 	DeprecatedContext  string            `yaml:"context,omitempty"`
 	DeprecatedReleases []ReleaseSpec     `yaml:"charts,omitempty"`
 	OverrideNamespace  string            `yaml:"namespace,omitempty"`
+	OverrideChart      string            `yaml:"chart,omitempty"`
 	Repositories       []RepositorySpec  `yaml:"repositories,omitempty"`
 	CommonLabels       map[string]string `yaml:"commonLabels,omitempty"`
 	Releases           []ReleaseSpec     `yaml:"releases,omitempty"`
@@ -999,6 +1000,9 @@ func (st *HelmState) PrepareCharts(helm helmexec.Interface, dir string, concurre
 		},
 		func(workerIndex int) {
 			for release := range jobQueue {
+				if st.OverrideChart != "" {
+					release.Chart = st.OverrideChart
+				}
 				// Call user-defined `prepare` hooks to create/modify local charts to be used by
 				// the later process.
 				//
@@ -2062,6 +2066,7 @@ func (st *HelmState) triggerGlobalReleaseEvent(evt string, evtErr error, helmfil
 		StateFilePath: st.FilePath,
 		BasePath:      st.basePath,
 		Namespace:     st.OverrideNamespace,
+		Chart:         st.OverrideChart,
 		Env:           st.Env,
 		Logger:        st.logger,
 		ReadFile:      st.readFile,
@@ -2094,6 +2099,7 @@ func (st *HelmState) triggerReleaseEvent(evt string, evtErr error, r *ReleaseSpe
 		StateFilePath: st.FilePath,
 		BasePath:      st.basePath,
 		Namespace:     st.OverrideNamespace,
+		Chart:         st.OverrideChart,
 		Env:           st.Env,
 		Logger:        st.logger,
 		ReadFile:      st.readFile,

pkg/state/state_exec_tmpl.go

@@ -20,6 +20,7 @@ func (st *HelmState) createReleaseTemplateData(release *ReleaseSpec, vals map[st
 	tmplData := releaseTemplateData{
 		Environment: st.Env,
 		Namespace:   st.OverrideNamespace,
+		Chart:       st.OverrideChart,
 		Values:      vals,
 		Release: releaseTemplateDataRelease{
 			Name:      release.Name,

pkg/state/types.go

@@ -34,6 +34,10 @@ type releaseTemplateData struct {
 	// You should better use Release.Namespace as it might work as you'd expect even if OverrideNamespace is not set.
 	// See releaseTemplateDataRelease.Namespace for more information.
 	Namespace string
+	// Chart is HelmState.OverrideChart.
+	// You should better use Release.Chart as it might work as you'd expect even if OverrideChart is not set.
+	// See releaseTemplateDataRelease.Chart for more information.
+	Chart string
 }
 
 type releaseTemplateDataRelease struct {