How to build Aliyun SMS passwordless sign-in with SvelteKit

For our new friends:

Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

In this article, we will go through the steps to quickly build the Aliyun sign-in experience (user authentication) with SvelteKit and Logto.

Prerequisites

A running Logto instance. Check out the introduction page to get started.
Basic knowledge of SvelteKit.
A usable Aliyun account.

Create an application in Logto

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Traditional web application, simply follow these steps:

Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button.
In the opening modal, click the "Traditional web" section or filter all the available "Traditional web" frameworks using the quick filter checkboxes on the left. Click the "SvelteKit" framework card to start creating your application.
Enter the application name, e.g., "Bookstore," and click "Create application".

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate SvelteKit with Logto

tip:

The following demonstration is built on SvelteKit 2.0.0.
The sample project is available in the GitHub repository.

Installation

Install Logto SDK via your favorite package manager:

npm
pnpm
yarn

npm i @logto/sveltekit

pnpm add @logto/sveltekit

yarn add @logto/sveltekit

Add Logto hook

In your hooks.server.ts file, add the following code to inject the Logto hook into your server:

hooks.server.ts
import { handleLogto } from '@logto/sveltekit';

export const handle = handleLogto(
  {
    endpoint: '<your-logto-endpoint>',
    appId: '<your-logto-app-id>',
    appSecret: '<your-logto-app-secret>',
  },
  {
    encryptionKey: '<a-random-string>',
  }
);

Since these information are sensitive, it's recommended to use environment variables:

hooks.server.ts
import { handleLogto } from '@logto/sveltekit';
import { env } from '$env/dynamic/private';

export const handle = handleLogto(
  {
    endpoint: env.LOGTO_ENDPOINT,
    appId: env.LOGTO_APP_ID,
    appSecret: env.LOGTO_APP_SECRET,
  },
  {
    encryptionKey: env.LOGTO_COOKIE_ENCRYPTION_KEY,
  }
);

If you have multiple hooks, you can use the sequence() helper function to chain them:

hooks.server.ts
import { sequence } from '@sveltejs/kit/hooks';

export const handle = sequence(handleLogto, handleOtherHook);

Now you can access the Logto client in the locals object. For TypeScript, you can add the type to app.d.ts:

import type { LogtoClient, UserInfoResponse } from '@logto/sveltekit';

declare global {
  namespace App {
    interface Locals {
      logtoClient: LogtoClient;
      user?: UserInfoResponse;
    }
  }
}

We'll discuss the user object later.

note:

In the following code snippets, we assume your app is running on http://localhost:3000/.

Before we dive into the details, here's a quick overview of the end-user experience. The sign-in process can be simplified as follows:

Your app invokes the sign-in method.
The user is redirected to the Logto sign-in page. For native apps, the system browser is opened.
The user signs in and is redirected back to your app (configured as the redirect URI).

This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

Configure redirect URIs

Switch to the application details page of Logto Console. Add a redirect URI http://localhost:3000/callback.

Just like signing in, users should be redirected to Logto for signing out of the shared session. Once finished, it would be great to redirect the user back to your website. For example, add http://localhost:3000/ as the post sign-out redirect URI section.

Then click "Save" to save the changes.

In the page where you want to implement sign-in and sign-out, define the following actions:

+page.server.ts
import type { Actions } from './$types';

export const actions: Actions = {
  signIn: async ({ locals }) => {
    await locals.logtoClient.signIn('http://localhost:3000/callback');
  },
  signOut: async ({ locals }) => {
    await locals.logtoClient.signOut('http://localhost:3000/');
  },
};

Then use these actions in your Svelte component:

+page.svelte
<form method="POST" action="?/{data.user ? 'signOut' : 'signIn'}">
  <button type="submit">Sign {data.user ? 'out' : 'in'}</button>
</form>

Checkpoint: Test your application

Now, you can test your application:

Run your application, you will see the sign-in button.
Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
After you signed in, you will be redirected back to your application and see the sign-out button.
Click the sign-out button to clear token storage and sign out.

Add Aliyun connector

SMS connector is a method used to send one-time passwords (OTPs) for authentication. It enables Phone number verification to support passwordless authentication, including SMS-based registration, sign-in, two-factor authentication (2FA), and account recovery. You can easily connect Aliyun as your SMS provider. With the Logto SMS connector, you can set this up in just a few minutes.

To add a SMS connector, simply follow these steps:

Navigate to Console > Connector > Email and SMS connectors.
To add a new SMS connector, click the "Set up" button and select "Aliyun".
Review the README documentation for your selected provider.
Complete the configuration fields in the "Parameter Configuration" section.
Customize the SMS template using the JSON editor.
Test your configuration by sending a verification code to your Phone number.

note:

If you are following the in-place Connector guide, you can skip the next section.

Set up Aliyun SMS connector

Set up a short message service in Aliyun SMS Console

Create an Aliyun account

Go to the Aliyun website and register your Aliyun account if you don't have one.

Enable and Configure Aliyun Short Message Service

Sign-in with your Aliyun account at the Aliyun website and go to the SMS service console page.
Click the "Open for free" (免费开通) button on the top left of the SMS service page and begin the configuration process.
Read and agree to the "SMS service activation Agreement" (短信服务开通条款) and click "Subscribe to a service" (开通服务) to move on.
You are now on the SMS service console page, go to either "Mainland China" (国内消息) or "Outside Mainland China" (国际/港澳台消息) button on the sidebar per your use case.
Add signature and template following the guidelines, and provide the materials or information required for review.
- Remember to select "Verification Code Message" (验证码) as "Scenario" (适用场景) when filling out the signature application and also "Verification Code Message" (验证码) for "Type" (模板类型) when applying for a template review because we are using these signatures and templates to send verification code. Currently, we do not support sending SMS messages other than verification-code-related text messages.
- Also, use {{code}} as a placeholder where you want to place your digital verification code in template contents.
After submitting your SMS signature and template application, you need to wait for it to take effect. At this point, we can go back to the SMS service console page and send a test SMS. If your signatures and templates are ready for use, you can try them directly; if they are not taking effect yet, Aliyun also provides test templates.
- You may need to recharge a small amount of money before sending test messages.
- You may also be asked to bind a test phone number before sending test messages. For more details, go to "Quick Start" (快速学习) tab from the sidebar of the SMS service console page.

Compose the connector JSON

From the SMS service console page, hover on your avatar in the top right corner and go to "AccessKey Management" (AccessKey 管理), and click "Create AccessKey" (创建 AccessKey). You will get an "AccessKey ID" and "AccessKey Secret" pair after finishing security verification. Please keep them properly.
Go to the "Mainland China" (国内消息) or "Outside Mainland China" (国际/港澳台消息) tab you just visited, you can find "Signature" (签名名称) and "Template Code" (模板 CODE) easily.
- If you want to use the test-only signature and template, go to the "Quick Start" (快速学习) tab instead, and you will find them below "Signature & Templates (For Test Only)".
Fill out the Aliyun SMS Connector settings:
- Fill out the accessKeyId and accessKeySecret fields with access key pairs you've got from step 1.
- Fill out the signName field with "Signature" (签名名称) which is mentioned in step 2. All templates will share this signature name.
- You can add multiple SMS connector templates for different cases. Here is an example of adding a single template:
  - Fill the templateCode field, which is how you can control SMS context, with "Template Code" (模板 CODE) from step 2.
  - Fill out usageType field with either Register, SignIn, ForgotPassword or Generic for different use cases. (usageType is a Logto property to identify the proper use case.) In order to enable full user flows, templates with usageType Register, SignIn, ForgotPassword and Generic are required.

Test Aliyun SMS connector

You can type in a phone number and click on "Send" to see whether the settings can work before "Save and Done".

That's it. Don't forget to Enable connector in sign-in experience.

Config types

Name	Type
accessKeyId	string
accessKeySecret	string
signName	string
templates	Template[]

Template Properties	Type	Enum values
templateCode	string	N/A
usageType	enum string	'Register' \| 'SignIn' \| 'ForgotPassword' \| 'Generic'

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the Aliyun connector should be available now.

Once you create a connector successfully, you can enable phone number-based passwordless login and registration.

Navigate to Console > Sign-in experience > Sign-up and sign-in.
Set up sign-up methods (Optional):
1. Select "Phone number" or "Email or phone number" as the sign-up identifier.
2. "Verify at sign-up" is forced to be enabled. You can also enable "Create a password" on registration.
Set up sign-in methods:
1. Select Phone number as one of sign-in identifiers. You can provide multiple available identifiers (email, phone number, and username).
2. Select "Verification code" and / or "Password" as the authentication factor.
Click "Save changes" and test it in "Live preview".

In addition to registration and login via OTPs, you can also have password recovery and -based security verification enabled, as well as linking Phone number to profile. See End-user flows for more details.

Testing and Validation

Return to your SvelteKit app. You should now be able to sign in with Aliyun. Enjoy!

Create an application in Logto​

Integrate SvelteKit with Logto​

Installation​

Add Logto hook​

Implement sign-in and sign-out​

Regarding redirect-based sign-in​

Configure redirect URIs​

Checkpoint: Test your application​

Add Aliyun connector​

Set up Aliyun SMS connector​

Set up a short message service in Aliyun SMS Console​

Create an Aliyun account​

Enable and Configure Aliyun Short Message Service​

Compose the connector JSON​

Test Aliyun SMS connector​

Config types​

Save your configuration​

Enable Aliyun connector in Sign-in Experience​

Testing and Validation​

Further readings​