Quadlet Kube: Add support for relative path for YAML file

If the provided path is relative, turn path to absolute
Add regex verification option in tests

Signed-off-by: Ygal Blum <ygal.blum@gmail.com>

pkg/systemd/quadlet/quadlet.go

@@ -2,6 +2,7 @@ package quadlet
 
 import (
 	"fmt"
+	"path/filepath"
 	"regexp"
 	"strings"
 
@@ -617,6 +618,18 @@ func ConvertKube(kube *parser.UnitFile) (*parser.UnitFile, error) {
 		return nil, fmt.Errorf("no Yaml key specified")
 	}
 
+	if !filepath.IsAbs(yamlPath) {
+		if len(kube.Path) > 0 {
+			yamlPath = filepath.Join(filepath.Dir(kube.Path), yamlPath)
+		} else {
+			var err error
+			yamlPath, err = filepath.Abs(yamlPath)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
 	// Only allow mixed or control-group, as nothing else works well
 	killMode, ok := service.Lookup(ServiceGroup, "KillMode")
 	if !ok || !(killMode == "mixed" || killMode == "control-group") {