Manager: serve static files of the webapp at /app/

Vue Router generates URLs for which there are no static files on the
filesystem (like `/jobs/{job ID}`). To make this work, the webapp's
`index.html` has to be served for such requests. The client-side JavaScript
then figures out how things fit together, and can even render a nice 404
page if necessary.

This shouldn't happen for non-webapp URLs, though. Because of this, the
entire webapp (including the "serve `index.html` if file not found logic)
is moved to a `/app/` base URL.

`make flamenco-manager` now also builds the webapp and embeds the static
files into the binary.

`make flamenco-manager_race` does NOT rebuild the static web files, to
help speed up of debug cycles. Run `make webapp-static` to rebuild the
webapp itself, if necessary, or run a separate web development server with
`yarn --cwd web/app run dev --host`.

.gitignore

@@ -20,3 +20,4 @@ __pycache__
 .openapi-generator/
 
 web/manager-api/dist/
+web/static/

Makefile

@@ -28,6 +28,7 @@ with-deps:
 application: flamenco-manager flamenco-worker webapp
 
 flamenco-manager:
+	$(MAKE) webapp-static
 	go build -v ${BUILD_FLAGS} ${PKG}/cmd/flamenco-manager
 
 flamenco-worker:
@@ -42,6 +43,14 @@ flamenco-worker_race:
 webapp:
 	yarn --cwd web/app install
 
+webapp-static:
+	rm -rf web/static
+# When changing the base URL, also update the line
+# e.GET("/app/*", echo.WrapHandler(webAppHandler))
+# in `cmd/flamenco-manager/main.go`
+	yarn --cwd web/app build --outDir ../static --base=/app/
+	@echo "Web app has been installed into web/static"
+
 generate: generate-go generate-py generate-js
 
 generate-go:

README.md

@@ -36,16 +36,15 @@ The web UI is built with Vue, Bootstrap, and Socket.IO for communication with th
 sudo snap install node --classic --channel=16
 ```
 
-This also gives you the Yarn package manager, which can be used to install web dependencies and build the frontend files.
+This also gives you the Yarn package manager, which can be used to install web dependencies and build the frontend files via:
 
 ```
-cd web/app
+make webapp
-yarn install
 ```
 
 Then run the frontend development server with:
 ```
-yarn run dev --host
+yarn --cwd web/app run dev --host
 ```
 
 The `--host` parameter is optional but recommended. The downside is that it
@@ -54,6 +53,9 @@ easier to detect configuration issues. The generated OpenAPI client defaults to
 using `localhost`, and if you're not testing on `localhost` this stands out
 more.
 
+The web interface is also "baked" into the `flamenco-manager` binary when using
+`make flamenco-manager`.
+
 
 ## Generating Code
 

cmd/flamenco-manager/main.go

@@ -44,6 +44,7 @@ import (
 	"git.blender.org/flamenco/internal/upnp_ssdp"
 	"git.blender.org/flamenco/pkg/api"
 	"git.blender.org/flamenco/pkg/shaman"
+	"git.blender.org/flamenco/web"
 )
 
 var cliArgs struct {
@@ -285,12 +286,6 @@ func buildWebService(
 		return c.JSON(http.StatusOK, swagger)
 	})
 
-	// Temporarily redirect the index page to the Swagger UI, so that at least you
-	// can see something.
-	e.GET("/", func(c echo.Context) error {
-		return c.Redirect(http.StatusTemporaryRedirect, "/api/swagger-ui/")
-	})
-
 	// Serve UPnP service descriptions.
 	if ssdp != nil {
 		e.GET(ssdp.DescriptionPath(), func(c echo.Context) error {
@@ -298,6 +293,21 @@ func buildWebService(
 		})
 	}
 
+	// Serve static files for the webapp on /app/.
+	webAppHandler, err := web.WebAppHandler()
+	if err != nil {
+		log.Fatal().Err(err).Msg("unable to set up HTTP server for embedded web app")
+	}
+	e.GET("/app/*", echo.WrapHandler(http.StripPrefix("/app", webAppHandler)))
+	e.GET("/app", func(c echo.Context) error {
+		return c.Redirect(http.StatusTemporaryRedirect, "/app/")
+	})
+
+	// Redirect / to the webapp.
+	e.GET("/", func(c echo.Context) error {
+		return c.Redirect(http.StatusTemporaryRedirect, "/app/")
+	})
+
 	// Log available routes
 	routeLogger := log.Level(zerolog.TraceLevel)
 	routeLogger.Trace().Msg("available routes:")

web/app/vite.config.js

@@ -1,6 +1,7 @@
 import { fileURLToPath, URL } from 'url'
 
 import { defineConfig } from 'vite'
+import { resolve } from 'path'
 import vue from '@vitejs/plugin-vue'
 
 // https://vitejs.dev/config/
@@ -10,5 +11,5 @@ export default defineConfig({
     alias: {
       '@': fileURLToPath(new URL('./src', import.meta.url))
     }
-  }
+  },
 })

web/web_app.go

@@ -0,0 +1,70 @@
+package web
+
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+import (
+	"embed"
+	"errors"
+	"fmt"
+	"io/fs"
+	"net/http"
+
+	"github.com/rs/zerolog/log"
+)
+
+//go:embed static
+var webStaticFS embed.FS
+
+// WebAppHandler returns a HTTP handler to serve the static files of the Flamenco Manager web app.
+func WebAppHandler() (http.Handler, error) {
+	// Strip the 'static/' directory off of the embedded filesystem.
+	fs, err := fs.Sub(webStaticFS, "static")
+	if err != nil {
+		return nil, fmt.Errorf("unable to wrap embedded filesystem: %w", err)
+	}
+
+	// Serve `index.html` from the root directory if the requested file cannot be
+	// found.
+	wrappedFS := WrapFS(fs, "index.html")
+
+	return http.FileServer(http.FS(wrappedFS)), nil
+}
+
+// FSWrapper wraps a filesystem and falls back to serving a specific file when
+// the requested file cannot be found.
+//
+// This is necesasry for compatibility with Vue Router, as that generates URL
+// paths to files that don't exist on the filesystem, like
+// `/workers/c441766a-5d28-47cb-9589-b0caa4269065`. Serving `/index.html` in
+// such cases makes Vue Router understand what's going on again.
+type FSWrapper struct {
+	fs       fs.FS
+	fallback string
+}
+
+func (w *FSWrapper) Open(name string) (fs.File, error) {
+	file, err := w.fs.Open(name)
+
+	switch {
+	case err == nil:
+		return file, nil
+	case errors.Is(err, fs.ErrNotExist):
+		fallbackFile, fallbackErr := w.fs.Open(w.fallback)
+		if fallbackErr != nil {
+			log.Error().
+				Str("name", name).
+				Str("fallback", w.fallback).
+				Err(err).
+				Str("fallbackErr", fallbackErr.Error()).
+				Msg("static web server: error opening fallback file")
+			return file, err
+		}
+		return fallbackFile, nil
+	}
+
+	return file, err
+}
+
+func WrapFS(fs fs.FS, fallback string) *FSWrapper {
+	return &FSWrapper{fs: fs, fallback: fallback}
+}