APP-8173: Make local testing for viam apps easier

cli/app.go

@@ -2479,6 +2479,19 @@ Note: There is no progress meter while copying is in progress.
 			UsageText:       createUsageText("module", nil, false, true),
 			HideHelpCommand: true,
 			Subcommands: []*cli.Command{
+				{
+					Name:      "local-app-testing",
+					Usage:     "test your viam application locally",
+					UsageText: createUsageText("module local-app-testing", []string{"port"}, false, false),
+					Flags: []cli.Flag{
+						&cli.IntFlag{
+							Name:  "port",
+							Usage: "port to run the local server on (default: 8000)",
+							Value: 8000,
+						},
+					},
+					Action: createCommandWithT[localAppTestingArgs](LocalAppTestingAction),
+				},
 				{
 					Name:  "create",
 					Usage: "create & register a module on app.viam.com",

cli/module_local_viam_apps_setup.go

@@ -0,0 +1,106 @@
+package cli
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"runtime"
+	"time"
+
+	"github.com/urfave/cli/v2"
+)
+
+// localAppTestingArgs contains the arguments for the local-app-testing command.
+type localAppTestingArgs struct {
+	Port int `json:"port"`
+}
+
+// LocalAppTestingAction is the action for the local-app-testing command.
+func LocalAppTestingAction(ctx *cli.Context, args localAppTestingArgs) error {
+	htmlPath, err := getHTMLFilePath()
+	if err != nil {
+		return err
+	}
+
+	server := setupHTTPServer(htmlPath, args.Port)
+	serverURL := fmt.Sprintf("http://localhost:%d", args.Port)
+
+	printf(ctx.App.Writer, "Starting server to locally test viam apps on %s", serverURL)
+	printf(ctx.App.Writer, "Press Ctrl+C to stop the server")
+
+	if err := startServerInBackground(server, ctx.App.Writer); err != nil {
+		return fmt.Errorf("failed to start server: %w", err)
+	}
+
+	if err := openbrowser(serverURL); err != nil {
+		printf(ctx.App.Writer, "Warning: Could not open browser: %v", err)
+	}
+
+	<-ctx.Context.Done()
+
+	if err := server.Shutdown(context.Background()); err != nil {
+		return fmt.Errorf("error shutting down server: %w", err)
+	}
+
+	return nil
+}
+
+// getHTMLFilePath returns the absolute path to module_local_viam_apps_test.html.
+func getHTMLFilePath() (string, error) {
+	_, currentFile, _, ok := runtime.Caller(0)
+	if !ok {
+		return "", errors.New("error getting current file path")
+	}
+	sourceDir := filepath.Dir(currentFile)
+
+	htmlPath := filepath.Join(sourceDir, "module_local_viam_apps_test.html")
+	absPath, err := filepath.Abs(htmlPath)
+	if err != nil {
+		return "", fmt.Errorf("error getting absolute path: %w", err)
+	}
+
+	if _, err := os.Stat(absPath); os.IsNotExist(err) {
+		return "", fmt.Errorf("module_local_viam_apps_test.html not found at: %s", absPath)
+	}
+
+	return absPath, nil
+}
+
+// setupHTTPServer creates and configures an HTTP server with the given HTML file.
+func setupHTTPServer(htmlPath string, port int) *http.Server {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Cache-Control", "no-store, no-cache, must-revalidate, max-age=0")
+		w.Header().Set("Pragma", "no-cache")
+		w.Header().Set("Expires", "0")
+
+		http.ServeFile(w, r, htmlPath)
+	})
+
+	return &http.Server{
+		Addr:              fmt.Sprintf(":%d", port),
+		ReadHeaderTimeout: time.Minute * 5,
+	}
+}
+
+// startServerInBackground starts the HTTP server in a goroutine and returns any startup errors.
+func startServerInBackground(server *http.Server, writer io.Writer) error {
+	errChan := make(chan error, 1)
+	go func() {
+		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			printf(writer, "Error starting server: %v", err)
+			errChan <- err
+		}
+		close(errChan)
+	}()
+
+	select {
+	case err := <-errChan:
+		return err
+	case <-time.After(100 * time.Millisecond):
+		return nil // Server started successfully
+	}
+}