Run cloud-config schema validation on-demand

Signed-off-by: Anders F Björklund <anders.f.bjorklund@gmail.com>

cmd/limactl/validate.go

@@ -1,9 +1,13 @@
 package main
 
 import (
+	"bufio"
+	"io"
 	"fmt"
+	"os"
 
 	"github.com/lima-vm/lima/cmd/limactl/guessarg"
+	"github.com/lima-vm/lima/pkg/cidata"
 	"github.com/lima-vm/lima/pkg/store"
 	"github.com/spf13/cobra"
 
@@ -21,15 +25,62 @@ func newValidateCommand() *cobra.Command {
 	return validateCommand
 }
 
+func firstLine(f string) (string, error) {
+	file, err := os.Open(f)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+	scanner := bufio.NewScanner(file)
+	scanner.Scan()
+	if err := scanner.Err(); err != nil {
+		return "", err
+	}
+	return scanner.Text(), nil
+}
+
+func validateCloudConfig(f string) error {
+	file, err := os.Open(f)
+	if err != nil {
+		return fmt.Errorf("failed to load YAML file %q: %w", f, err)
+	}
+	defer file.Close()
+	b, err := io.ReadAll(file)
+	if err != nil {
+		return err
+	}
+	if err = cidata.ValidateCloudConfig(b); err != nil {
+		return err
+	}
+	return nil
+}
+
+func validateLimayaml(f string) error {
+	_, err := store.LoadYAMLByFilePath(f)
+	if err != nil {
+		return fmt.Errorf("failed to load YAML file %q: %w", f, err)
+	}
+	if _, err := guessarg.InstNameFromYAMLPath(f); err != nil {
+		return err
+	}
+	return nil
+}
+
 func validateAction(_ *cobra.Command, args []string) error {
 	for _, f := range args {
-		_, err := store.LoadYAMLByFilePath(f)
+		line, err := firstLine(f)
 		if err != nil {
-			return fmt.Errorf("failed to load YAML file %q: %w", f, err)
-		}
-		if _, err := guessarg.InstNameFromYAMLPath(f); err != nil {
 			return err
 		}
+		if line == "#cloud-config" {
+			if err := validateCloudConfig(f); err != nil {
+				return err
+			}
+		} else {
+			if err := validateLimayaml(f); err != nil {
+				return err
+			}
+		}
 		logrus.Infof("%q: OK", f)
 	}
 

pkg/cidata/schema.go

@@ -1,9 +1,7 @@
 package cidata
 
 import (
-	"bytes"
 	_ "embed"
-	"fmt"
 	"strings"
 
 	"github.com/santhosh-tekuri/jsonschema/v5"
@@ -16,10 +14,7 @@ const schemaURL = "https://raw.githubusercontent.com/canonical/cloud-init/main/c
 //go:embed schemas/schema-cloud-config-v1.json
 var schemaText string
 
-func validateCloudConfig(userData []byte) error {
-	if !bytes.HasPrefix(userData, []byte("#cloud-config")) {
-		return fmt.Errorf("missing #cloud-config")
-	}
+func ValidateCloudConfig(userData []byte) error {
 	var m interface{}
 	err := yaml.Unmarshal(userData, &m)
 	if err != nil {

pkg/cidata/schema_test.go

@@ -11,6 +11,6 @@ func TestValidate(t *testing.T) {
 users:
    - default
 `
-	err := validateCloudConfig([]byte(config))
+	err := ValidateCloudConfig([]byte(config))
 	assert.NilError(t, err)
 }

pkg/cidata/template.go

@@ -147,11 +147,6 @@ func ExecuteTemplate(args TemplateArgs) ([]iso9660util.Entry, error) {
 		if err != nil {
 			return err
 		}
-		if d.Name() == "user-data" {
-			if err := validateCloudConfig(b); err != nil {
-				return err
-			}
-		}
 		layout = append(layout, iso9660util.Entry{
 			Path:   path,
 			Reader: bytes.NewReader(b),