Node.js Entry Point (REQUIRED)

Azure Functions Node.js v4 programming model requires an entry point file that initializes the runtime.

⛔ CRITICAL: Without this file, functions will deploy but return 404 on all endpoints.

Project Structure (CRITICAL)

The project structure MUST be:

project-root/                # ← azure.yaml project: "."
├── azure.yaml
├── package.json             # ← MUST be at ROOT, not in src/
├── host.json
├── src/
│   ├── index.js             # ← Entry point (app.setup)
│   └── functions/
│       ├── myFunction.js    # ← Functions auto-discovered
│       └── ...
└── infra/

⛔ CRITICAL: package.json MUST be at project root, NOT inside src/. The azure.yaml must have project: . (not project: ./src/).

JavaScript: src/index.js

This file MUST exist and MUST NOT be removed when replacing trigger files.

const { app } = require('@azure/functions');

app.setup({
    enableHttpStream: true,
});

TypeScript: src/index.ts

This file MUST exist and MUST NOT be removed when replacing trigger files.

import { app } from '@azure/functions';

app.setup({
    enableHttpStream: true,
});

package.json Configuration

The package.json MUST be at the project root (same level as azure.yaml).

⛔ CRITICAL: The glob pattern is REQUIRED for function discovery! Using "main": "src/index.js" alone will result in 404 on all endpoints. You MUST use the glob pattern that includes function files.

JavaScript (REQUIRED pattern)

{
  "main": "src/{index.js,functions/*.js}",
  "scripts": {
    "start": "func start"
  }
}

TypeScript (REQUIRED pattern)

{
  "main": "dist/src/{index.js,functions/*.js}",
  "scripts": {
    "build": "tsc",
    "prestart": "npm run build",
    "start": "func start"
  }
}

Why the Glob Pattern is Required: The Azure Functions Node.js v4 runtime uses the main field to determine which files to load. Unlike CommonJS where require() chains work, the runtime needs ALL function files explicitly listed in the glob pattern. Without the glob, only index.js loads and functions in src/functions/ are never registered.

❌ WRONG: "main": "src/index.js" — Functions not discovered, 404 on all routes ✅ CORRECT: "main": "src/\{index.js,functions/*.js\}" — All functions discovered

azure.yaml Configuration

services:
  api:
    project: .           # ← ROOT directory, not ./src/
    language: js         # or ts for TypeScript
    host: function

⛔ CRITICAL: Use project: . — NOT project: ./src/. The runtime expects package.json at the project root.

Build Requirements (TypeScript only)

Before deployment, TypeScript must be compiled:

npm run build

This outputs JavaScript to dist/ which is what Azure Functions actually runs.

Common Mistakes

Mistake	Symptom	Fix
Using "main": "src/index.js" without glob	404 on all endpoints	Use "main": "src/\{index.js,functions/*.js\}"
Missing src/index.js	404 on all endpoints	Add the entry point file with app.setup()
Deleting src/index.js when replacing triggers	404 after recipe applied	Keep index.js, only replace function files
package.json in src/ instead of root	404, functions not found	Move package.json to project root
project: ./src/ in azure.yaml	Deployment fails or 404	Use project: .
Missing npm run build for TypeScript	404 or old code runs	Run build before deploy

⛔ #1 CAUSE OF 404 ERRORS: Using "main": "src/index.js" instead of the glob pattern. The glob src/\{index.js,functions/*.js\} is REQUIRED — it's not optional!

Terraform vs Bicep: Source Code is IDENTICAL

The Node.js source code and package.json are exactly the same for both IaC types.

Only the infra/ folder differs:

• Bicep: infra/*.bicep
• Terraform: infra/*.tf

⚠️ If you find yourself changing imports or source code because of IaC choice, something is wrong. The application code should be IaC-agnostic.