refactor: add some more useful templating funcs (#4891)

docs/content/en/reference/guides/templating.md

@@ -78,6 +78,9 @@ The following functions which mimic the behaviour of helm exist in most templati
 - kindIs
 - default
 - empty
+- indent
+- nindent
+- uuidv4
 
 See the [Helm Documentation](https://helm.sh/docs/chart_template_guide/function_list/) for more information. Please
 note that only the functions listed above are supported and the functions don't necessarily behave exactly the same.
@@ -92,3 +95,7 @@ The following is a list of special functions and their syntax.
 #### iterate
 
 Input is a single uint. Returns a slice of uints from 0 to the provided uint.
+
+#### fileContent
+
+Input is a path. Returns the content of a file.

internal/templates/funcs.go

@@ -17,12 +17,15 @@ import (
 	"strconv"
 	"strings"
 	"time"
+
+	"github.com/google/uuid"
 )
 
 // FuncMap returns the template FuncMap commonly used in several templates.
 func FuncMap() map[string]any {
 	return map[string]any{
 		"iterate":     FuncIterate,
+		"fileContent": FuncFileContent,
 		"env":         FuncGetEnv,
 		"expandenv":   FuncExpandEnv,
 		"split":       FuncStringSplit,
@@ -73,6 +76,9 @@ func FuncMap() map[string]any {
 		"kindIs":      FuncKindIs,
 		"default":     FuncDefault,
 		"empty":       FuncEmpty,
+		"indent":      FuncIndent,
+		"nindent":     FuncNewlineIndent,
+		"uuidv4":      FuncUUIDv4,
 	}
 }
 
@@ -384,3 +390,31 @@ func FuncEmpty(v any) bool {
 		return false
 	}
 }
+
+// FuncIndent is a helper function that provides similar functionality to the helm indent func.
+func FuncIndent(indent int, value string) string {
+	padding := strings.Repeat(" ", indent)
+
+	return padding + strings.ReplaceAll(value, "\n", "\n"+padding)
+}
+
+// FuncNewlineIndent is a helper function that provides similar functionality to the helm nindent func.
+func FuncNewlineIndent(indent int, value string) string {
+	return "\n" + FuncIndent(indent, value)
+}
+
+// FuncUUIDv4 is a helper function that provides similar functionality to the helm uuidv4 func.
+func FuncUUIDv4() string {
+	return uuid.New().String()
+}
+
+// FuncFileContent returns the file content.
+func FuncFileContent(path string) (data string, err error) {
+	var raw []byte
+
+	if raw, err = os.ReadFile(path); err != nil {
+		return "", err
+	}
+
+	return string(raw), nil
+}

internal/templates/funcs_test.go

@@ -638,3 +638,23 @@ func TestFuncEmpty(t *testing.T) {
 		})
 	}
 }
+
+func TestFuncIndent(t *testing.T) {
+	testCases := []struct {
+		name     string
+		have     string
+		indent   int
+		expected []string
+	}{
+		{"ShouldIndentZeroMultiLine", "abc\n123", 0, []string{"abc\n123", "\nabc\n123"}},
+		{"ShouldIndentOneMultiLine", "abc\n123", 1, []string{" abc\n 123", "\n abc\n 123"}},
+		{"ShouldIndentOneSingleLine", "abc", 1, []string{" abc", "\n abc"}},
+		{"ShouldIndentZeroSingleLine", "abc", 0, []string{"abc", "\nabc"}},
+	}
+
+	for _, tc := range testCases {
+		for i, f := range []func(i int, v string) string{FuncIndent, FuncNewlineIndent} {
+			assert.Equal(t, tc.expected[i], f(tc.indent, tc.have))
+		}
+	}
+}