webui(dm): always redircet to index page (#4350)

ref #3583

dm/ui/server.go

@@ -18,27 +18,49 @@ package ui
 import (
 	"io/fs"
 	"net/http"
+	"strings"
 
 	"github.com/gin-gonic/gin"
 	"github.com/pingcap/tiflow/dm/openapi"
 	"github.com/pingcap/tiflow/dm/pkg/log"
 	"go.uber.org/zap"
 )
 
+const (
+	buildPath  = "dist"
+	assetsPath = "assets"
+	indexPath  = "/dashboard/"
+)
+
 // WebUIAssetsHandler returns a http handler for serving static files.
 func WebUIAssetsHandler() http.FileSystem {
-	stripped, err := fs.Sub(WebUIAssets, "dist")
+	stripped, err := fs.Sub(WebUIAssets, buildPath)
 	if err != nil {
 		panic(err) // this should never happen
 	}
 	return http.FS(stripped)
 }
 
+// we need this to handle this case: user want to access /dashboard/source.html/ but webui is a single page app,
+// and it only can handle requests in index page, so we need to redirect to index page.
+func alwaysRedirect(path string) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		// note that static file like css and js under the assets folder should not be redirected.
+		if c.Request.URL.Path != path && !strings.Contains(c.Request.URL.Path, assetsPath) {
+			c.Redirect(http.StatusPermanentRedirect, path)
+			c.AbortWithStatus(http.StatusPermanentRedirect)
+		} else {
+			c.Next()
+		}
+	}
+}
+
 // InitWebUIRouter initializes the webUI router.
 func InitWebUIRouter() *gin.Engine {
 	router := gin.New()
 	router.Use(gin.Recovery())
+	router.Use(alwaysRedirect(indexPath))
 	router.Use(openapi.ZapLogger(log.L().WithFields(zap.String("component", "webui")).Logger))
-	router.StaticFS("/dashboard/", WebUIAssetsHandler())
+	router.StaticFS(indexPath, WebUIAssetsHandler())
 	return router
 }