Added support for running NodeJS Databricks apps locally (#3092)

## Changes
Added support for running NodeJS Databricks apps locally

## Why
This supports running NodeJS apps (in debug mode as well) locally in a
similar way we do for Python apps by running
```
databricks apps run-local --prepare-environment --debug
```

## Tests
Added acceptance tests

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release,
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Author: andrewnester

acceptance/cmd/workspace/apps/run-local-node/app/.gitignore

@@ -0,0 +1 @@
+node_modules

acceptance/cmd/workspace/apps/run-local-node/app/app.js

@@ -0,0 +1,27 @@
+const express = require('express');
+const app = express();
+const port = process.env.PORT || 8000;
+
+// Root route
+app.get('/', (req, res) => {
+  res.json({
+    message: 'Hello From App',
+    timestamp: new Date().toISOString(),
+    status: 'running'
+  });
+});
+
+app.get('/shutdown', (req, res) => {
+  console.log('Server closed')
+  // Add a small delay to ensure response is sent before exit
+  setTimeout(() => {
+    process.exit(0);
+  }, 1000);
+});
+
+// Start the server
+app.listen(port, () => {
+  console.log(`Server is running on port ${port}`);
+});
+
+module.exports = app;

acceptance/cmd/workspace/apps/run-local-node/app/app.yml

@@ -0,0 +1,4 @@
+command:
+  - npm
+  - run
+  - run-app

acceptance/cmd/workspace/apps/run-local-node/app/package.json

@@ -0,0 +1,13 @@
+{
+    "name": "app",
+    "version": "1.0.0",
+    "description": "A simple Node.js app",
+    "main": "app.js",
+    "scripts": {
+        "run-app": "node app.js",
+        "build": "echo 'Building app...'"
+    },
+    "dependencies": {
+        "express": "^5.1.0"
+    }
+}

acceptance/cmd/workspace/apps/run-local-node/app/test.yml

@@ -0,0 +1,4 @@
+command:
+  - node
+  - -e
+  - "console.log('Hello, world')"

acceptance/cmd/workspace/apps/run-local-node/output.txt

@@ -0,0 +1,12 @@
+Running command: node -e console.log('Hello, world')
+Hello, world
+
+=== Starting the app in background...
+=== Waiting
+=== Checking app is running...
+>>> curl -s -o - http://127.0.0.1:$(port)
+{"message":"Hello From App","timestamp":"[TIMESTAMP]","status":"running"}
+
+=== Sending shutdown request...
+>>> curl -s -o /dev/null http://127.0.0.1:$(port)/shutdown
+Process terminated

acceptance/cmd/workspace/apps/run-local-node/script

@@ -0,0 +1,47 @@
+cd app
+
+# We first run the command with different entry point which starts unblocking script
+# so we don't need to start it in background. It will install the dependencies as part of the command
+trace $CLI apps run-local --prepare-environment --entry-point test.yml 2>&1 | grep -w "Hello, world"
+
+# Get 3 unique ports sequentially to avoid conflicts
+PORTS=$(allocate_ports.py 3 | tr -d '\r')
+
+# Read ports into array
+PORTS_ARR=($(echo "$PORTS"))
+PORT="${PORTS_ARR[0]}"
+DEBUG_PORT="${PORTS_ARR[1]}"
+PROXY_PORT="${PORTS_ARR[2]}"
+
+title "Starting the app in background..."
+trace $CLI apps run-local --prepare-environment --debug --port "$PROXY_PORT" --debug-port "$DEBUG_PORT" --app-port "$PORT" > ../out.run.txt 2>&1 &
+PID=$!
+# Ensure background process is killed on script exit
+trap '(kill $PID >/dev/null 2>&1) 2>/dev/null || true' EXIT
+cd ..
+
+title Waiting for the app to start...
+# Use a loop to check for the startup message instead of tail/sed which can be unreliable on Windows
+# due to file locking, buffering issues, and different text processing behavior across Windows versions.
+# A simple grep loop is more robust across platforms.
+while [ -z "$(grep -o "Server is running on port " out.run.txt 2>/dev/null)" ]; do
+    sleep 1
+done
+
+title "Checking app is running..."
+trace curl -s -o - http://127.0.0.1:$PROXY_PORT | grep -w "Hello From App"
+
+title "Sending shutdown request..."
+trace curl -s -o /dev/null  http://127.0.0.1:$PROXY_PORT/shutdown || true
+
+# We need to wait for the app to shutdown before we can exit the test meaning wait until the
+# server is closed. We need to poll because the server is closed asynchronously.
+while [ -z "$(grep -o "Server closed" out.run.txt 2>/dev/null)" ]; do
+    sleep 1
+done
+
+# Wait for the background process to actually terminate
+wait $PID 2>/dev/null || true
+echo "Process terminated"
+
+rm out.run.txt

acceptance/cmd/workspace/apps/run-local-node/test.toml

@@ -0,0 +1,20 @@
+RecordRequests = false
+Timeout = '2m'
+TimeoutWindows = '10m'
+
+Ignore = [
+    'node_modules',
+    'package-lock.json'
+]
+
+[[Repls]]
+Old='curl/[0-9]+\.[0-9]+\.[0-9]+'
+New='curl/(version)'
+
+[[Repls]]
+Old='127.0.0.1:[0-9]+'
+New='127.0.0.1:$(port)'
+
+[[Repls]]
+Old='To debug your app, attach a debugger to port [0-9]+'
+New='To debug your app, attach a debugger to port $(debug_port)'

cmd/workspace/apps/run_local.go

@@ -53,7 +53,11 @@ func setupWorkspaceAndConfig(cmd *cobra.Command, entryPoint string, appPort int)
 func setupApp(cmd *cobra.Command, config *apps.Config, spec *apps.AppSpec, customEnv []string, prepareEnvironment bool) (apps.App, []string, error) {
 	ctx := cmd.Context()
 	cfg := cmdctx.ConfigUsed(ctx)
-	app := apps.NewApp(ctx, config, spec)
+	app, err := apps.NewApp(ctx, config, spec)
+	if err != nil {
+		return nil, nil, err
+	}
+
 	env := auth.ProcessEnv(cfg)
 	if cfg.Profile != "" {
 		env = append(env, "DATABRICKS_CONFIG_PROFILE="+cfg.Profile)

libs/apps/apps.go

@@ -1,14 +1,28 @@
 package apps
 
-import "context"
+import (
+	"context"
+	"os"
+	"path/filepath"
+)
 
 type App interface {
 	PrepareEnvironment() error
 	GetCommand(bool) ([]string, error)
 }
 
-func NewApp(ctx context.Context, config *Config, spec *AppSpec) App {
-	// We only support python apps for now, but later we can add more types
-	// based on AppSpec
-	return NewPythonApp(ctx, config, spec)
+func NewApp(ctx context.Context, config *Config, spec *AppSpec) (App, error) {
+	// Check if the app is a Node.js app by checking if there is a package.json file in the root of the app
+	packageJsonPath := filepath.Join(config.AppPath, "package.json")
+	_, err := os.Stat(packageJsonPath)
+	if err == nil {
+		// Read the package.json file
+		packageJson, err := readPackageJson(packageJsonPath)
+		if err != nil {
+			return nil, err
+		}
+		return NewNodeApp(ctx, config, spec, packageJson), nil
+	}
+
+	return NewPythonApp(ctx, config, spec), nil
 }