azfn-express

This package allows you to expose an ExpressJS application as a serverless app using Azure Functions.

All Express routing and middleware is supported. A single Azure function handles your entire API.

Using the new v4 programming model, natively streamed requests and responses are also supported, just as if you were using standalone Express.

Requirements

• Your Azure Functions app is using the new v4 programming model

Quick Start

1. Add this package to your app: yarn add azfn-express or npm install azfn-express
2. Use the register function to register your Express application with Azure Functions. Make sure the file this is in gets imported eventually from your main entrypoint.

import { register } from 'azfn-express';
import { myExpressApp } from './app';

register(myExpressApp);

This will register your app with sensible defaults, as well as enable HTTP Streaming in your Azure app. A function called 'Api' will be created, that will handle all incoming requests.

Note: By default, Azure Functions has a base URL path of /api. The adapter does not strip this out, so your Express app routing needs to take the prefix into account.

Detailed Instructions

For more customization, you may provide the name of the app, or a configuration object that will be passed straight to the Azure registration function, or both.

register(myExpressApp, 'MyApi', {route: '/myapi/{*segments}'})

register(myExpressApp, {
    methods: ['GET'], 
    authLevel: 'function'
});

For even more control, instead of using register, you can use createHandler which will return the handler function for you to register yourself.

import { app } from '@azure/functions';
import { createHandler } from 'azfn-express';
import { myExpressApp } from './app';

app.setup({ enableHttpStream: true })
app.http('MyApi', {
    handler: createHandler(myExpressApp),
    route: '{*segments}'
});

Inside Express

Request bodies are always provided to Express as a raw stream only. You will need to add Express middlewares for parsing JSON and so on. This package does not use the internal Azure methods for body parsing.

Two extra properties will be available on the Express request object:

• context - this is the Azure Functions invocation context, used for logging and so on
• user - if using Azure authentication, this will be the user object, if there is one

See the Express documentation for how to handle streaming requests and responses, if you wish to do so. You may also use the Express send method, or any other Express functionality.