feat: use comments instead of frontmatter

template.go

@@ -257,18 +257,18 @@ func LoadSharedLibrary(source string) error {
 }
 
 func parseAndStripTemplateHeader(template Template) (Template, error) {
-	fm, content := extractFrontmatterAndContent(template.Template)
-	if fm == "" {
+	header, content := extractHeaderAndContent(template.Template)
+	if header == "" {
 		return template, nil
 	}
 
 	template.Template = content
-	scanner := bufio.NewScanner(strings.NewReader(fm))
-	for scanner.Scan() {
-		line := scanner.Text()
-		split := strings.SplitN(line, "=", 2)
+
+	fields := strings.Fields(header)
+	for _, field := range fields {
+		split := strings.SplitN(field, "=", 2)
 		if len(split) != 2 {
-			return template, fmt.Errorf("invalid header: %s", line)
+			return template, fmt.Errorf("invalid header: %s", field)
 		}
 
 		switch split[0] {
@@ -282,23 +282,32 @@ func parseAndStripTemplateHeader(template Template) (Template, error) {
 	return template, nil
 }
 
-func extractFrontmatterAndContent(input string) (string, string) {
-	const delimiter = "---"
+const templateHeaderPrefix = "# gotemplate: "
 
-	input = strings.TrimSpace(input)
+func extractHeaderAndContent(template string) (string, string) {
+	scanner := bufio.NewScanner(strings.NewReader(template))
 
-	if !strings.HasPrefix(input, delimiter) {
-		return "", input
-	}
+	// Loop through headers.
+	// There could be multiple, we look for the gotemplate header.
+	for scanner.Scan() {
+		line := scanner.Text()
 
-	endIndex := strings.Index(input[len(delimiter):], delimiter)
-	if endIndex == -1 {
-		return "", input
-	}
+		if line == "---" {
+			// Special case for yaml where the header might not start from the first line.
+			continue
+		}
+
+		// end of headers.
+		isHeader := strings.HasPrefix(line, "#")
+		if !isHeader {
+			break
+		}
 
-	frontmatterEndIndex := endIndex + 2*len(delimiter)
-	frontmatter := strings.TrimSpace(input[len(delimiter) : endIndex+len(delimiter)])
-	content := strings.TrimSpace(input[frontmatterEndIndex:])
+		if strings.HasPrefix(line, templateHeaderPrefix) {
+			header := strings.TrimPrefix(line, templateHeaderPrefix)
+			return header, strings.Replace(template, fmt.Sprintf("%s\n", line), "", 1)
+		}
+	}
 
-	return frontmatter, content
+	return "", template
 }

tests/gomplate_test.go

@@ -1,6 +1,7 @@
 package tests
 
 import (
+	"fmt"
 	"os"
 	"testing"
 	"time"
@@ -84,20 +85,28 @@ func TestGomplate(t *testing.T) {
 
 func TestGomplateHeaders(t *testing.T) {
 	tests := []struct {
-		env      map[string]interface{}
-		template string
-		out      string
+		env       map[string]interface{}
+		template  string
+		out       string
+		expectErr bool
 	}{
-		{map[string]interface{}{"name": "world"}, readFile(t, "testdata/template-header.txt"), "Hello, world"},
+		{map[string]interface{}{"name": "world"}, readFile(t, "testdata/gotemplate/template-multiple-headers.yaml"), readFile(t, "testdata/gotemplate/expected/template-multiple-headers.yaml"), false},
+		{map[string]interface{}{"name": "world"}, readFile(t, "testdata/gotemplate/template-header.txt"), "Hello, world", false},
+		{map[string]interface{}{"name": "world"}, readFile(t, "testdata/gotemplate/bad-template-header.txt"), "", true},
+		{map[string]interface{}{"name": "world"}, readFile(t, "testdata/gotemplate/template-header-override.txt"), "Hello, world. This ${should} not be {{touched}}", false},
 	}
 
-	for _, tc := range tests {
-		t.Run(tc.template, func(t *testing.T) {
+	for i, tc := range tests {
+		t.Run(fmt.Sprintf("%d", i+1), func(t *testing.T) {
 			out, err := gomplate.RunTemplate(tc.env, gomplate.Template{
 				Template: tc.template,
 			})
-			assert.ErrorIs(t, err, nil)
-			assert.Equal(t, tc.out, out)
+			if tc.expectErr {
+				assert.Error(t, err)
+			} else {
+				assert.ErrorIs(t, err, nil)
+				assert.Equal(t, tc.out, out)
+			}
 		})
 	}
 }

tests/testdata/gotemplate/bad-template-header.txt

@@ -0,0 +1,2 @@
+# gotemplate: left-delim=$[ [ right-delim=]]
+Hello, $[[.name]]

tests/testdata/gotemplate/expected/template-multiple-headers.yaml

@@ -0,0 +1,3 @@
+---
+# yaml-language-server: $schema=https://raw.githubusercontent.com/fluxcd-community/flux2-schemas/main/helmrepository-source-v1beta2.json
+name: Hello world

tests/testdata/gotemplate/template-header-override.txt

@@ -0,0 +1,2 @@
+# gotemplate: left-delim=$[[ right-delim=]]
+Hello, $[[.name]]. This ${should} not be {{touched}}

tests/testdata/gotemplate/template-header.txt

@@ -0,0 +1,2 @@
+# gotemplate: left-delim=$[[ right-delim=]]
+Hello, $[[.name]]

tests/testdata/gotemplate/template-multiple-headers.yaml

@@ -0,0 +1,4 @@
+---
+# yaml-language-server: $schema=https://raw.githubusercontent.com/fluxcd-community/flux2-schemas/main/helmrepository-source-v1beta2.json
+# gotemplate: left-delim=<<< right-delim=>>>
+name: Hello <<<.name>>>