limayaml: add a check to verify whether the variables defined in param are actually used

This check needs to be performed before the template is expanded, so it should be added before calling `FillDefault()`.

Signed-off-by: Norio Nomura <[email protected]>

Author: norio-nomura

pkg/limayaml/load.go

@@ -86,6 +86,11 @@ func Load(b []byte, filePath string) (*LimaYAML, error) {
 		return nil, err
 	}
 
+	// It should be called before the `y` parameter is passed to FillDefault() that execute template.
+	if err := ValidateParamIsUsed(&y); err != nil {
+		return nil, err
+	}
+
 	FillDefault(&y, &d, &o, filePath)
 	return &y, nil
 }

pkg/limayaml/validate.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"regexp"
 	"runtime"
 	"strings"
 
@@ -252,7 +253,7 @@ func Validate(y *LimaYAML, warn bool) error {
 		}
 		if rule.GuestSocket != "" {
 			if !path.IsAbs(rule.GuestSocket) {
-				return fmt.Errorf("field `%s.guestSocket` must be an absolute path", field)
+				return fmt.Errorf("field `%s.guestSocket` must be an absolute path, but is %q", field, rule.GuestSocket)
 			}
 			if rule.HostSocket == "" && rule.HostPortRange[1]-rule.HostPortRange[0] > 0 {
 				return fmt.Errorf("field `%s.guestSocket` can only be mapped to a single port or socket. not a range", field)
@@ -287,7 +288,7 @@ func Validate(y *LimaYAML, warn bool) error {
 		field := fmt.Sprintf("CopyToHost[%d]", i)
 		if rule.GuestFile != "" {
 			if !path.IsAbs(rule.GuestFile) {
-				return fmt.Errorf("field `%s.guest` must be an absolute path", field)
+				return fmt.Errorf("field `%s.guest` must be an absolute path, but is %q", field, rule.GuestFile)
 			}
 		}
 		if rule.HostFile != "" {
@@ -385,6 +386,46 @@ func validateNetwork(y *LimaYAML) error {
 	return nil
 }
 
+// ValidateParamIsUsed checks if the keys in the `param` field are used in any script, probe, copyToHost, or portForward.
+// It should be called before the `y` parameter is passed to FillDefault() that execute template.
+func ValidateParamIsUsed(y *LimaYAML) error {
+	for key := range y.Param {
+		re, err := regexp.Compile(`{{[^}]*\.Param\.` + key + `[^}]*}}`)
+		if err != nil {
+			return fmt.Errorf("field to compile regexp for key %q: %w", key, err)
+		}
+		keyIsUsed := false
+		for _, p := range y.Provision {
+			if re.MatchString(p.Script) {
+				keyIsUsed = true
+				break
+			}
+		}
+		for _, p := range y.Probes {
+			if re.MatchString(p.Script) {
+				keyIsUsed = true
+				break
+			}
+		}
+		for _, p := range y.CopyToHost {
+			if re.MatchString(p.GuestFile) || re.MatchString(p.HostFile) {
+				keyIsUsed = true
+				break
+			}
+		}
+		for _, p := range y.PortForwards {
+			if re.MatchString(p.GuestSocket) || re.MatchString(p.HostSocket) {
+				keyIsUsed = true
+				break
+			}
+		}
+		if !keyIsUsed {
+			return fmt.Errorf("field `param` key %q is not used in any provision, probe, copyToHost, or portForward", key)
+		}
+	}
+	return nil
+}
+
 func validatePort(field string, port int) error {
 	switch {
 	case port < 0:

pkg/limayaml/validate_test.go

@@ -30,3 +30,24 @@ func TestValidateDefault(t *testing.T) {
 	err = Validate(y, true)
 	assert.NilError(t, err)
 }
+
+func TestValidateParamIsUsed(t *testing.T) {
+	paramYaml := `param:
+  name: value`
+	_, err := Load([]byte(paramYaml), "paramIsNotUsed.yaml")
+	assert.Error(t, err, "field `param` key \"name\" is not used in any provision, probe, copyToHost, or portForward")
+
+	fieldsUsingParam := []string{
+		`provision: [{"script": "echo {{ .Param.name }}"}]`,
+		`probes: [{"script": "echo {{ .Param.name }}"}]`,
+		`copyToHost: [{"guest": "/tmp/{{ .Param.name }}", "host": "/tmp"}]`,
+		`copyToHost: [{"guest": "/tmp", "host": "/tmp/{{ .Param.name }}"}]`,
+		`portForwards: [{"guestSocket": "/tmp/{{ .Param.name }}", "hostSocket": "/tmp"}]`,
+		`portForwards: [{"guestSocket": "/tmp", "hostSocket": "/tmp/{{ .Param.name }}"}]`,
+	}
+	for _, fieldUsingParam := range fieldsUsingParam {
+		_, err = Load([]byte(fieldUsingParam+"\n"+paramYaml), "paramIsUsed.yaml")
+		//
+		assert.NilError(t, err)
+	}
+}