Add validate method to runsc config bundles.

Validate checks a config bundle map that all flags exist and their values
are valid for each flag.

PiperOrigin-RevId: 512791071

runsc/config/config.go

@@ -27,6 +27,7 @@ import (
 
 	"gvisor.dev/gvisor/pkg/refs"
 	"gvisor.dev/gvisor/pkg/sentry/watchdog"
+	"gvisor.dev/gvisor/runsc/flag"
 )
 
 // Config holds configuration that is not part of the runtime spec.
@@ -376,6 +377,22 @@ type Bundle map[string]string
 // It is used as part of an annotation to specify that the user wants to apply a Bundle.
 type BundleName string
 
+// Validate validates that given flag string values map to actual flags in runsc.
+func (b Bundle) Validate() error {
+	flagSet := flag.NewFlagSet("tmp", flag.ContinueOnError)
+	RegisterFlags(flagSet)
+	for key, val := range b {
+		flag := flagSet.Lookup(key)
+		if flag == nil {
+			return fmt.Errorf("unknown flag %q", key)
+		}
+		if err := flagSet.Set(key, val); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // MetricMetadata returns key-value pairs that are useful to include in metrics
 // exported about the sandbox this config represents.
 func (c *Config) MetricMetadata() map[string]string {

runsc/config/config_test.go

@@ -15,6 +15,7 @@
 package config
 
 import (
+	"fmt"
 	"reflect"
 	"strings"
 	"testing"
@@ -664,3 +665,51 @@ func TestBundles(t *testing.T) {
 		})
 	}
 }
+
+func TestBundleValidate(t *testing.T) {
+	defaultVerify := func(err error) error { return err }
+	for _, tc := range []struct {
+		name   string
+		bundle Bundle
+		verify func(err error) error
+	}{
+		{
+			name:   "empty bundle",
+			bundle: Bundle(map[string]string{}),
+			verify: defaultVerify,
+		},
+		{
+			name:   "invalid flag bundle",
+			bundle: Bundle(map[string]string{"not-a-real-flag": "true"}),
+			verify: func(err error) error {
+				want := `unknown flag "not-a-real-flag"`
+				if !strings.Contains(err.Error(), want) {
+					return fmt.Errorf("mismatch error: got: %q want: %q", err.Error(), want)
+				}
+				return nil
+			},
+		},
+		{
+			name:   "invalid value",
+			bundle: Bundle(map[string]string{"debug": "invalid"}),
+			verify: func(err error) error {
+				want := `parsing "invalid": invalid syntax`
+				if !strings.Contains(err.Error(), want) {
+					return fmt.Errorf("mismatch error: got: %q want: %q", err.Error(), want)
+				}
+				return nil
+			},
+		},
+		{
+			name:   "valid flag bundle",
+			bundle: Bundle(map[string]string{"debug": "true"}),
+			verify: defaultVerify,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if err := tc.verify(tc.bundle.Validate()); err != nil {
+				t.Fatalf("Validate failed: %v", err)
+			}
+		})
+	}
+}