Drop comments from config files (#272)

* feat: drop commented lines from config files

* feat: drop comments, not lines, from config files

pkg/config/envvar/envvar.go

@@ -11,6 +11,11 @@ import (
 )
 
 func ExpandInContent(content []byte) ([]byte, error) {
+	content, err := removeComments(content)
+	if err != nil {
+		return nil, fmt.Errorf("cannot remove configuration commented lines, error: %w", err)
+	}
+
 	r := regexp.MustCompile(`({{ *\w+.*?}})`)
 	matches := r.FindAllIndex(content, -1)
 
@@ -43,3 +48,30 @@ func ExpandInContent(content []byte) ([]byte, error) {
 
 	return newContent, nil
 }
+
+func removeComments(content []byte) ([]byte, error) {
+	r := regexp.MustCompile(`(^[ \t#].*\n)|([ \t]*#.*)`)
+	matches := r.FindAllIndex(content, -1)
+	if len(matches) == 0 {
+		return content, nil
+	}
+
+	var newContent []byte
+	var lastReplacement int
+	for _, idx := range matches {
+		lineStart := idx[0]
+		lineEnd := idx[1]
+		if len(content) < lineStart || len(content) < lineEnd {
+			return content, fmt.Errorf("cannot remove commented lines from config")
+		}
+		newContent = append(newContent, content[lastReplacement:lineStart]...)
+		lastReplacement = lineEnd
+
+	}
+
+	if lastReplacement != len(content) {
+		newContent = append(newContent, content[lastReplacement:]...)
+	}
+
+	return newContent, nil
+}

pkg/config/envvar/envvar_test.go

@@ -30,6 +30,11 @@ func TestExpandInContent(t *testing.T) {
 		{"2 placeholder with 2 env-var", map[string]string{"BAR1": "VAL1", "BAR2": "VAL2"}, "foo: {{BAR1}}\nbaz: {{BAR2}}", "foo: VAL1\nbaz: VAL2", false},
 		{"1 placeholder with 1 env-var special chars", map[string]string{"BAR": "$.*^"}, "foo: {{BAR}}\nbaz", "foo: $.*^\nbaz", false},
 		{"1 placeholder with 1 env-var numeric", map[string]string{"BAR": "1"}, "foo: {{BAR}}", "foo: 1", false},
+		// comments removal
+		{"1 placeholder within comment lines are stripped", emptyEnv, "#foo: {{BAR}}\nbaz", "baz", false},
+		{"comment lines starting with spaces are stripped", emptyEnv, "  #foo: {{BAR}}\nbaz", "baz", false},
+		{"comment lines starting with tab are stripped", emptyEnv, "\t #foo: {{BAR}}\nbaz", "baz", false},
+		{"comment part of the line is dropped while previous content is kept", emptyEnv, "foo: bar # {{BAR}}\nbaz", "foo: bar\nbaz", false},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {