CI: Move verify-storybook command from grabpl (#59928)

* Move verify-storybook from grabpl

* Remove zerolog

pkg/build/cmd/main.go

@@ -152,7 +152,7 @@ func main() {
 		},
 		{
 			Name:   "store-storybook",
-			Usage:  "Integrity check for storybook build",
+			Usage:  "Stores storybook to GCS buckets",
 			Action: StoreStorybook,
 			Flags: []cli.Flag{
 				&cli.StringFlag{
@@ -161,6 +161,11 @@ func main() {
 				},
 			},
 		},
+		{
+			Name:   "verify-storybook",
+			Usage:  "Integrity check for storybook build",
+			Action: VerifyStorybook,
+		},
 		{
 			Name:   "upload-packages",
 			Usage:  "Upload Grafana packages",

pkg/build/cmd/verifystorybook.go

@@ -0,0 +1,32 @@
+// Package verifystorybook contains the sub-command "verify-storybook".
+package main
+
+import (
+	"fmt"
+	"log"
+	"path/filepath"
+
+	"github.com/grafana/grafana/pkg/infra/fs"
+	"github.com/urfave/cli/v2"
+)
+
+// VerifyStorybook Action implements the sub-command "verify-storybook".
+func VerifyStorybook(c *cli.Context) error {
+	const grafanaDir = "."
+
+	paths := []string{
+		"packages/grafana-ui/dist/storybook/index.html",
+		"packages/grafana-ui/dist/storybook/iframe.html"}
+	for _, p := range paths {
+		exists, err := fs.Exists(filepath.Join(grafanaDir, p))
+		if err != nil {
+			return cli.NewExitError(fmt.Sprintf("failed to verify Storybook build: %s", err), 1)
+		}
+		if !exists {
+			return fmt.Errorf("failed to verify Storybook build, missing %q", p)
+		}
+	}
+
+	log.Printf("Successfully verified Storybook integrity")
+	return nil
+}