`@shopify/koa-shopify-auth`

Middleware to authenticate a Koa application with Shopify.

Sister module to @shopify/shopify-express, but simplified.

Features you might know from the express module like the webhook middleware and proxy will be presented as their own packages instead.

Warning: versions prior to 3.1.68 vulnerable to reflected XSS

Versions prior to 3.1.68 are vulnerable to a reflected XSS attack. Please update to the latest version to protect your app.

Installation

This package builds upon the Shopify Node Library, so your app will have access to all of the library's features as well as the Koa-specific middlewares this package provides.

$ yarn add @shopify/koa-shopify-auth

Usage

This package exposes shopifyAuth by default, and verifyRequest as a named export. To make it ready for use, you need to initialize the Shopify Library and then use that to initialize this package:

import shopifyAuth, {verifyRequest} from '@shopify/koa-shopify-auth';
import Shopify, {ApiVersion} from '@shopify/shopify-api';

// Initialize the library
Shopify.Context.initialize({
  API_KEY: 'Your API_KEY',
  API_SECRET_KEY: 'Your API_SECRET_KEY',
  SCOPES: ['Your scopes'],
  HOST_NAME: 'Your HOST_NAME (omit the https:// part)',
  API_VERSION: ApiVersion.October20,
  IS_EMBEDDED_APP: true,
  // More information at https://github.com/Shopify/shopify-node-api/blob/main/docs/issues.md#notes-on-session-handling
  SESSION_STORAGE: new Shopify.Session.MemorySessionStorage(),
});

shopifyAuth

Returns an authentication middleware taking up (by default) the routes /auth and /auth/callback.

app.use(
  shopifyAuth({
    // if specified, mounts the routes off of the given path
    // eg. /shopify/auth, /shopify/auth/callback
    // defaults to ''
    prefix: '/shopify',
    // set access mode, default is 'online'
    accessMode: 'offline',
    // callback for when auth is completed
    afterAuth(ctx) {
      const { shop, accessToken } = ctx.state.shopify;

      console.log('We did it!', accessToken);

      ctx.redirect('/');
    },
  }),
);

`/auth`

This route starts the oauth process. It expects a ?shop parameter and will error out if one is not present. To install it in a store just go to /auth?shop=myStoreSubdomain.

`/auth/callback`

You should never have to manually go here. This route is purely for shopify to send data back during the oauth process.

`verifyRequest`

Returns a middleware to verify requests before letting them further in the chain.

Note: if you're using a prefix for shopifyAuth, that prefix needs to be present in the paths for authRoute and fallbackRoute below.

app.use(
  verifyRequest({
    // path to redirect to if verification fails
    // defaults to '/auth'
    authRoute: '/foo/auth',
    // path to redirect to if verification fails and there is no shop on the query
    // defaults to '/auth'
    fallbackRoute: '/install',
    // which access mode is being used
    // defaults to 'online'
    accessMode: 'offline',
  }),
);

Migrating from cookie-based authentication to session tokens

Versions prior to v4 of this package used cookies to store session information for your app. However, internet browsers have been moving to block 3rd party cookies, which creates issues for embedded apps.

If you have an app using this package, you can migrate from cookie-based authentication to session tokens by performing a few steps:

Upgrade your @shopify/koa-shopify-auth dependency to v4+
Update your server as per the Usage instructions to properly initialize the @shopify/shopify-api library
If you are using accessMode: 'offline' in shopifyAuth, make sure to pass the same value in verifyRequest
Install @shopify/app-bridge-utils in your frontend app
In your frontend app, replace fetch calls with authenticatedFetch from App Bridge Utils

Note: the backend steps need to be performed to fully migrate your app to v4, even if your app is not embedded.

You can learn more about session tokens in our authentication tutorial. Go to the frontend changes section under Setup for instructions and examples on how to update your frontend code.

Example app

This example will enable you to quickly set up the backend for a working development app. Please read the Gotchas session below to make sure you are ready for production use.

import 'isomorphic-fetch';

import Koa from 'koa';
import session from 'koa-session';
import shopifyAuth, {verifyRequest} from '@shopify/koa-shopify-auth';
import Shopify, {ApiVersion} from '@shopify/shopify-api';

// initializes the library
Shopify.Context.initialize({
  API_KEY: process.env.SHOPIFY_API_KEY,
  API_SECRET_KEY: process.env.SHOPIFY_SECRET,
  SCOPES: ['Your scopes'],
  HOST_NAME: 'Your HOST_NAME (omit the https:// part)',
  API_VERSION: ApiVersion.October20,
  IS_EMBEDDED_APP: true,
  SESSION_STORAGE: new Shopify.Session.MemorySessionStorage(),
});

const app = new Koa();
app.keys = [Shopify.Context.API_SECRET_KEY];

app
  // sets up secure session data on each request
  .use(session({secure: true, sameSite: 'none'}, app))

  // sets up shopify auth
  .use(
    shopifyAuth({
      afterAuth(ctx) {
        const {shop, accessToken} = ctx.state.shopify;

        console.log('We did it!', accessToken);

        ctx.redirect('/');
      },
    }),
  )

  // everything after this point will require authentication
  .use(verifyRequest())

  // application code
  .use(ctx => {
    ctx.body = '🎉';
  });

Gotchas

Session

The provided MemorySessionStorage class may not be scalable for production use. You can implement your own strategy by creating a class that implements a few key methods. Learn more about how the Shopify Library handles sessions.

Testing locally

By default this app requires that you use a myshopify.com host in the shop parameter. You can modify this to test against a local/staging environment via the myShopifyDomain option to shopifyAuth (e.g. myshopify.io).

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