feat(values): Add Support for Values Directory

New CLI flag --values-directory (or) -d for loading directory name
which has the values YAML files.

This flag will be used by the following commands:
1. Install
2. Lint
3. Package
4. Upgrade

The values directory(s) (or the values inside the values YAML files
inside the specified directory(s)) are processed first. i.e., values
from other input types (--values, --set-json, --set, --set-string,
--set-file, --set-literal) can all overwrite values from directories
if matching keys.

Fixes #10416

Signed-off-by: Bhargav Ravuri <bhargav.ravuri@infracloud.io>

cmd/helm/flags.go

@@ -44,6 +44,7 @@ const (
 
 func addValueOptionsFlags(f *pflag.FlagSet, v *values.Options) {
 	f.StringSliceVarP(&v.ValueFiles, "values", "f", []string{}, "specify values in a YAML file or a URL (can specify multiple)")
+	f.StringSliceVarP(&v.ValuesDirectories, "values-directory", "d", []string{}, "specify values directory to recursively read for value's YAML files. Note: The YAML files in the directory are read in the lexical order. (can specify multiple)")
 	f.StringArrayVar(&v.Values, "set", []string{}, "set values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)")
 	f.StringArrayVar(&v.StringValues, "set-string", []string{}, "set STRING values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)")
 	f.StringArrayVar(&v.FileValues, "set-file", []string{}, "set values from respective files specified via the command line (can specify multiple or separate values with commas: key1=path1,key2=path2)")

pkg/cli/values/options.go

@@ -18,8 +18,10 @@ package values
 
 import (
 	"io"
+	"io/fs"
 	"net/url"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/pkg/errors"
@@ -31,21 +33,48 @@ import (
 
 // Options captures the different ways to specify values
 type Options struct {
-	ValueFiles    []string // -f/--values
-	StringValues  []string // --set-string
-	Values        []string // --set
-	FileValues    []string // --set-file
-	JSONValues    []string // --set-json
-	LiteralValues []string // --set-literal
+	ValueFiles        []string // -f/--values
+	ValuesDirectories []string // -d/--values-directory
+	StringValues      []string // --set-string
+	Values            []string // --set
+	FileValues        []string // --set-file
+	JSONValues        []string // --set-json
+	LiteralValues     []string // --set-literal
 }
 
-// MergeValues merges values from files specified via -f/--values and directly
-// via --set-json, --set, --set-string, or --set-file, marshaling them to YAML
+// MergeValues merges values specified via any of the following flags, and marshals them to YAML:
+// 1. -d/--values-directory - from values file(s) in the directory(s)
+// 2. -f/--values			- from values file(s) or URL
+// 3. 	 --set-json			- from input JSON
+// 4. 	 --set				- from input key-value pairs
+// 5. 	 --set-string		- from input key-value pairs, with string values, always
+// 6. 	 --set-file			- from files
+// 7. 	 --set-literal		- from input string literal
+//
+// The precedence order of inputs are 1 to 7, where 1 gets evaluated first and 7 last. i.e., If key1="val1" in inputs
+// from --values-directory, and key1="val2" in --values, the second overwrites the first and the final value of key1
+// is "val2". Similarly values from --set-json are replaced from that of --values, and so on.
 func (opts *Options) MergeValues(p getter.Providers) (map[string]interface{}, error) {
 	base := map[string]interface{}{}
 
-	// User specified a values files via -f/--values
-	for _, filePath := range opts.ValueFiles {
+	var valuesFiles []string
+
+	// User specified directory(s) via -d/--values-directory
+	for _, dir := range opts.ValuesDirectories {
+		// Recursive list of YAML files in input values directory
+		files, err := recursiveListOfFilesInDir(dir, `.yaml`)
+		if err != nil {
+			// Error already wrapped
+			return nil, err
+		}
+
+		valuesFiles = append(valuesFiles, files...)
+	}
+
+	// User specified values files via -f/--values
+	valuesFiles = append(valuesFiles, opts.ValueFiles...)
+
+	for _, filePath := range valuesFiles {
 		currentMap := map[string]interface{}{}
 
 		bytes, err := readFile(filePath, p)
@@ -145,3 +174,31 @@ func readFile(filePath string, p getter.Providers) ([]byte, error) {
 	}
 	return data.Bytes(), err
 }
+
+// recursiveListOfFilesInDir lists the directory recursively, i.e., files in all nested directories.
+// The list can be filtered by file extension. If no extension is specified, it returns all files.
+//
+// Result format: [<dir>/<file>, ..., <dir>/<sub-dir>/<file> ...]
+func recursiveListOfFilesInDir(directory, extension string) ([]string, error) {
+	var files []string
+
+	// Traverse through the directory, recursively
+	err := filepath.WalkDir(directory, func(path string, file fs.DirEntry, err error) error {
+		// Check if accessing the file failed
+		if err != nil {
+			return errors.Wrapf(err, "failed to read info of file %q", path)
+		}
+
+		// When the file has the required extension, or when extension is not specified
+		if !file.IsDir() && (extension == "" || filepath.Ext(path) == extension) {
+			files = append(files, path)
+		}
+
+		return nil
+	})
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to recursively list files in directory %q", directory)
+	}
+
+	return files, nil
+}

pkg/cli/values/options_test.go

@@ -23,7 +23,7 @@ import (
 	"helm.sh/helm/v3/pkg/getter"
 )
 
-func TestMergeValues(t *testing.T) {
+func Test_mergeMaps(t *testing.T) {
 	nestedMap := map[string]interface{}{
 		"foo": "bar",
 		"baz": map[string]string{
@@ -86,3 +86,147 @@ func TestReadFile(t *testing.T) {
 		t.Errorf("Expected error when has special strings")
 	}
 }
+
+func TestOptions_MergeValues(t *testing.T) {
+	const (
+		crewNameKey      = `crew`
+		shipNameKey      = `ship`
+		powerUserskey    = `power-users`
+		nonPowerUsersKey = `non-power-users`
+		strawHatsCrew    = `Straw Hat Pirates`
+		strawHatsShip1   = `Going Merry`
+		strawHatsShip2   = `Thousand Sunny`
+	)
+
+	var (
+		powerUsersVal = []interface{}{
+			"Luffy",
+			"Chopper",
+			"Robin",
+			"Brook",
+		}
+		nonPowerUsersVal = []interface{}{
+			"Zoro",
+			"Nami",
+			"Ussop",
+			"Sanji",
+			"Franky",
+			"Jinbei",
+		}
+	)
+
+	type args struct {
+		p getter.Providers
+	}
+	tests := []struct {
+		name    string
+		opts    Options
+		args    args
+		want    map[string]interface{}
+		wantErr bool
+	}{
+		{
+			name: "--values-directory with single level",
+			opts: Options{
+				ValueFiles: []string{},
+				ValuesDirectories: []string{
+					"testdata/chart-with-values-dir/values.d",
+				},
+				StringValues: []string{},
+				Values:       []string{},
+				FileValues:   []string{},
+				JSONValues:   []string{},
+			},
+			args: args{
+				p: []getter.Provider{},
+			},
+			want: map[string]interface{}{
+				powerUserskey:    powerUsersVal,
+				nonPowerUsersKey: nonPowerUsersVal,
+			},
+			wantErr: false,
+		},
+		{
+			name: "--values-directory with nested directories",
+			opts: Options{
+				ValueFiles: []string{},
+				ValuesDirectories: []string{
+					"testdata/multi-level-values-dir/values.d",
+				},
+				StringValues: []string{},
+				Values:       []string{},
+				FileValues:   []string{},
+				JSONValues:   []string{},
+			},
+			args: args{
+				p: []getter.Provider{},
+			},
+			want: map[string]interface{}{
+				crewNameKey:      strawHatsCrew,
+				shipNameKey:      strawHatsShip1,
+				powerUserskey:    powerUsersVal,
+				nonPowerUsersKey: nonPowerUsersVal,
+			},
+			wantErr: false,
+		},
+		{
+			name: "--values-directory value overwritten by --values",
+			opts: Options{
+				ValueFiles: []string{
+					"testdata/multi-level-values-dir/ship.yaml",
+				},
+				ValuesDirectories: []string{
+					"testdata/multi-level-values-dir/values.d",
+				},
+				StringValues: []string{},
+				Values:       []string{},
+				FileValues:   []string{},
+				JSONValues:   []string{},
+			},
+			args: args{
+				p: []getter.Provider{},
+			},
+			want: map[string]interface{}{
+				crewNameKey:      strawHatsCrew,
+				shipNameKey:      strawHatsShip2, // This is the value overwritten by values file "ship.yaml"
+				powerUserskey:    powerUsersVal,
+				nonPowerUsersKey: nonPowerUsersVal,
+			},
+			wantErr: false,
+		},
+		{
+			name: "--values-directory with missing directory",
+			opts: Options{
+				ValueFiles: []string{},
+				ValuesDirectories: []string{
+					"testdata/chart-with-values-dir/non-existing/",
+				},
+				StringValues: []string{},
+				Values:       []string{},
+				FileValues:   []string{},
+				JSONValues:   []string{},
+			},
+			args: args{
+				p: []getter.Provider{},
+			},
+			want:    map[string]interface{}(nil),
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := tt.opts.MergeValues(tt.args.p)
+
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Options.MergeValues() error = %v, wantErr %v", err, tt.wantErr)
+
+				return
+			}
+
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Expected result from MergeValues() = %v, got %v", tt.want, got)
+			}
+		})
+	}
+}

pkg/cli/values/testdata/chart-with-values-dir/values.d/non-power-users.yaml

@@ -0,0 +1,7 @@
+non-power-users:
+  - Zoro
+  - Nami
+  - Ussop
+  - Sanji
+  - Franky
+  - Jinbei

pkg/cli/values/testdata/chart-with-values-dir/values.d/power-users.yaml

@@ -0,0 +1,5 @@
+power-users:
+ - Luffy
+ - Chopper
+ - Robin
+ - Brook

pkg/cli/values/testdata/multi-level-values-dir/ship.yaml

@@ -0,0 +1 @@
+ship: Thousand Sunny

pkg/cli/values/testdata/multi-level-values-dir/values.d/extras/crew.yaml

@@ -0,0 +1 @@
+crew: Straw Hat Pirates

pkg/cli/values/testdata/multi-level-values-dir/values.d/extras/ship.yaml

@@ -0,0 +1 @@
+ship: Going Merry

pkg/cli/values/testdata/multi-level-values-dir/values.d/non-power-users.yaml

@@ -0,0 +1,7 @@
+non-power-users:
+  - Zoro
+  - Nami
+  - Ussop
+  - Sanji
+  - Franky
+  - Jinbei

pkg/cli/values/testdata/multi-level-values-dir/values.d/power-users.yaml

@@ -0,0 +1,5 @@
+power-users:
+ - Luffy
+ - Chopper
+ - Robin
+ - Brook