tailscale/client/web/assets.go
Sonia Appasamy 1eadb2b608 client/web: clean up assets handling
A #cleanup that moves all frontend asset handling into assets.go
(formerly dev.go), and stores a single assetsHandler field back
to web.Server that manages when to serve the dev vite proxy versus
static files itself.

Signed-off-by: Sonia Appasamy <sonia@tailscale.com>
2023-09-08 16:05:11 -04:00

108 lines
3.4 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package web
import (
"embed"
"io/fs"
"log"
"net/http"
"net/http/httputil"
"net/url"
"os"
"os/exec"
"path/filepath"
"strings"
"tailscale.com/util/must"
)
// This contains all files needed to build the frontend assets.
// Because we assign this to the blank identifier, it does not actually embed the files.
// However, this does cause `go mod vendor` to include the files when vendoring the package.
// External packages that use the web client can `go mod vendor`, run `yarn build` to
// build the assets, then those asset bundles will be embedded.
//
//go:embed yarn.lock index.html *.js *.json src/*
var _ embed.FS
//go:embed build/*
var embeddedFS embed.FS
// staticfiles serves static files from the build directory.
var staticfiles http.Handler
func init() {
buildFiles := must.Get(fs.Sub(embeddedFS, "build"))
staticfiles = http.FileServer(http.FS(buildFiles))
}
func assetsHandler(devMode bool) (_ http.Handler, cleanup func()) {
if devMode {
// When in dev mode, proxy asset requests to the Vite dev server.
cleanup := startDevServer()
return devServerProxy(), cleanup
}
return staticfiles, nil
}
// startDevServer starts the JS dev server that does on-demand rebuilding
// and serving of web client JS and CSS resources.
func startDevServer() (cleanup func()) {
root := gitRootDir()
webClientPath := filepath.Join(root, "client", "web")
yarn := filepath.Join(root, "tool", "yarn")
node := filepath.Join(root, "tool", "node")
vite := filepath.Join(webClientPath, "node_modules", ".bin", "vite")
log.Printf("installing JavaScript deps using %s... (might take ~30s)", yarn)
out, err := exec.Command(yarn, "--non-interactive", "-s", "--cwd", webClientPath, "install").CombinedOutput()
if err != nil {
log.Fatalf("error running tailscale web's yarn install: %v, %s", err, out)
}
log.Printf("starting JavaScript dev server...")
cmd := exec.Command(node, vite)
cmd.Dir = webClientPath
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
if err := cmd.Start(); err != nil {
log.Fatalf("Starting JS dev server: %v", err)
}
log.Printf("JavaScript dev server running as pid %d", cmd.Process.Pid)
return func() {
cmd.Process.Signal(os.Interrupt)
err := cmd.Wait()
log.Printf("JavaScript dev server exited: %v", err)
}
}
// devServerProxy returns a reverse proxy to the vite dev server.
func devServerProxy() *httputil.ReverseProxy {
// We use Vite to develop on the web client.
// Vite starts up its own local server for development,
// which we proxy requests to from Server.ServeHTTP.
// Here we set up the proxy to Vite's server.
handleErr := func(w http.ResponseWriter, r *http.Request, err error) {
w.Header().Set("Content-Type", "text/plain")
w.WriteHeader(http.StatusBadGateway)
w.Write([]byte("The web client development server isn't running. " +
"Run `./tool/yarn --cwd client/web start` from " +
"the repo root to start the development server."))
w.Write([]byte("\n\nError: " + err.Error()))
}
viteTarget, _ := url.Parse("http://127.0.0.1:4000")
devProxy := httputil.NewSingleHostReverseProxy(viteTarget)
devProxy.ErrorHandler = handleErr
return devProxy
}
func gitRootDir() string {
top, err := exec.Command("git", "rev-parse", "--show-toplevel").Output()
if err != nil {
log.Fatalf("failed to find git top level (not in corp git?): %v", err)
}
return strings.TrimSpace(string(top))
}