How to build Alipay (Web) sign-in with Go

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 Alipay (Web) sign-in experience (user authentication) with Go and Logto.

Prerequisites

A running Logto instance. Check out the introduction page to get started.
Basic knowledge of Go.
A usable Alipay (Web) 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 "Go" 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 Go with Logto

tip:

The following demonstration is built upon the Gin Web Framework. You may also integrate Logto into other frameworks by taking the same steps.
The Go sample project is available on our Go SDK repo.

Installation

Execute in the project root directory:

go get github.com/logto-io/go

Add the github.com/logto-io/go/client package to your application code:

main.go
// main.go
package main

import (
	"github.com/gin-gonic/gin"
	// Add dependency
	"github.com/logto-io/go/client"
)

func main() {
	router := gin.Default()
	router.GET("/", func(c *gin.Context) {
		c.String(200, "Hello Logto!")
	})
	router.Run(":3000")
}

Create a session storage

In traditional web applications, the user authentication information will be stored in the user session.

Logto SDK provides a Storage interface, you can implement a Storage adapter based on your web framework so that the Logto SDK can store user authentication information in the session.

note:

We do NOT recommend using cookie-based sessions, as user authentication information stored by Logto may exceed the cookie size limit. In this example, we use memory-based sessions. You can use Redis, MongoDB, and other technologies in production to store sessions as needed.

The Storage type in the Logto SDK is as follows:

github.com/logto-io/client/storage.go
package client

type Storage interface {
	GetItem(key string) string
	SetItem(key, value string)
}

We use github.com/gin-contrib/sessions middleware as an example to demonstrate this process.

Apply the middleware to the application, so that we can get the user session by the user request context in the route handler:

main.go
package main

import (
	"github.com/gin-contrib/sessions"
	"github.com/gin-contrib/sessions/memstore"
	"github.com/gin-gonic/gin"
	"github.com/logto-io/go/client"
)

func main() {
	router := gin.Default()

	// We use memory-based session in this example
	store := memstore.NewStore([]byte("your session secret"))
	router.Use(sessions.Sessions("logto-session", store))

	router.GET("/", func(ctx *gin.Context) {
		// Get user session
		session := sessions.Default(ctx)
		// ...
		ctx.String(200, "Hello Logto!")
	})
	router.Run(":3000")
}

Create a session_storage.go file, define a SessionStorage and implement the Logto SDK's Storage interfaces:

session_storage.go
package main

import (
	"github.com/gin-contrib/sessions"
)

type SessionStorage struct {
	session sessions.Session
}

func (storage *SessionStorage) GetItem(key string) string {
	value := storage.session.Get(key)
	if value == nil {
		return ""
	}
	return value.(string)
}

func (storage *SessionStorage) SetItem(key, value string) {
	storage.session.Set(key, value)
	storage.session.Save()
}

Now, in the route handler, you can create a session storage for Logto:

session := sessions.Default(ctx)
sessionStorage := &SessionStorage{session: session}

Init LogtoClient

First, create a Logto config:

main.go
func main() {
	// ...
	logtoConfig := &client.LogtoConfig{
		Endpoint:  "<your-logto-endpoint>", // E.g. http://localhost:3001
		AppId:     "<your-application-id>",
		AppSecret: "<your-application-secret>",
	}
	// ...
}

tip:

You can find and copy "App Secret" from application details page in Admin Console:

Then, you can create a LogtoClient for each user request with the Logto config above:

main.go
func main() {
	// ...

	router.GET("/", func(ctx *gin.Context) {
		// Create LogtoClient
		session := sessions.Default(ctx)
		logtoClient := client.NewLogtoClient(
			logtoConfig,
			&SessionStorage{session: session},
		)

		// Use Logto to control the content of the home page
		authState := "You are not logged in to this website. :("

		if logtoClient.IsAuthenticated() {
			authState = "You are logged in to this website! :)"
		}

		homePage := `<h1>Hello Logto</h1>` +
			"<div>" + authState + "</div>"

		ctx.Data(http.StatusOK, "text/html; charset=utf-8", []byte(homePage))
	})

	// ...
}

After the redirect URI is configured, we add a sign-in route to handle the sign-in request and also add an sign-in link on the home page:

main.go
func main() {
	// ...

	// Add a link to perform a sign-in request on the home page
	router.GET("/", func(ctx *gin.Context) {
		// ...
		homePage := `<h1>Hello Logto</h1>` +
			"<div>" + authState + "</div>" +
			// Add link
			`<div><a href="/sign-in">Sign In</a></div>`

		ctx.Data(http.StatusOK, "text/html; charset=utf-8", []byte(homePage))
	})

	// Add a route for handling sign-in requests
	router.GET("/sign-in", func(ctx *gin.Context) {
		session := sessions.Default(ctx)
		logtoClient := client.NewLogtoClient(
			logtoConfig,
			&SessionStorage{session: session},
		)

		// The sign-in request is handled by Logto.
		// The user will be redirected to the Redirect URI on signed in.
		signInUri, err := logtoClient.SignIn("http://localhost:3000/callback")
		if err != nil {
			ctx.String(http.StatusInternalServerError, err.Error())
			return
		}

		// Redirect the user to the Logto sign-in page.
		ctx.Redirect(http.StatusTemporaryRedirect, signInUri)
	})

	// ...
}

Now, when your user visit http://localhost:3000/sign-in, the user will be redirected to the Logto sign-in page.

Implement the callback route

When the user signs in successfully on the Logto sign-in page, Logto will redirect the user to the Redirect URI.

Since the redirect URI is http://localhost:3000/callback, we add the /callback route to handle the callback after signing in.

main.go
func main() {
	// ...

	// Add a route for handling sign-in callback requests
	router.GET("/callback", func(ctx *gin.Context) {
		session := sessions.Default(ctx)
		logtoClient := client.NewLogtoClient(
			logtoConfig,
			&SessionStorage{session: session},
		)

		// The sign-in callback request is handled by Logto
		err := logtoClient.HandleSignInCallback(ctx.Request)
		if err != nil {
			ctx.String(http.StatusInternalServerError, err.Error())
			return
		}

		// Jump to the page specified by the developer.
		// This example takes the user back to the home page.
		ctx.Redirect(http.StatusTemporaryRedirect, "/")
	})

	// ...
}

Implement sign-out route

Similar to the sign-in flow, when the user signs out, Logto will redirect the user to the post sign-out redirect URI.

Now, let's add the sign-out route to handle the sign-out request and also add a sign-out link on the home page:

main.go
func main() {
	// ...

	// Add a link to perform a sign-out request on the home page
	router.GET("/", func(ctx *gin.Context) {
		// ...
		homePage := `<h1>Hello Logto</h1>` +
			"<div>" + authState + "</div>" +
			`<div><a href="/sign-in">Sign In</a></div>` +
			// Add link
			`<div><a href="/sign-out">Sign Out</a></div>`

		ctx.Data(http.StatusOK, "text/html; charset=utf-8", []byte(homePage))
	})

	// Add a route for handling signing out requests
	router.GET("/sign-out", func(ctx *gin.Context) {
		session := sessions.Default(ctx)
		logtoClient := client.NewLogtoClient(
			logtoConfig,
			&SessionStorage{session: session},
		)

		// The sign-out request is handled by Logto.
		// The user will be redirected to the Post Sign-out Redirect URI on signed out.
		signOutUri, signOutErr := logtoClient.SignOut("http://localhost:3000")

		if signOutErr != nil {
			ctx.String(http.StatusOK, signOutErr.Error())
			return
		}

		ctx.Redirect(http.StatusTemporaryRedirect, signOutUri)
	})

	// ...
}

After the user makes a signing-out request, Logto will clear all user authentication information in the session.

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 Alipay (Web) connector

To enable quick sign-in and improve user conversion, connect with Go as an identity provider. The Logto social connector helps you establish this connection in minutes by allowing several parameter inputs.

To add a social connector, simply follow these steps:

Navigate to Console > Connectors > Social Connectors.
Click "Add social connector" and select "Alipay (Web)".
Follow the README guide and complete required fields and customize settings.

note:

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

Set up Alipay web app

Register Alipay developer account

Create and configure Alipay app

Sign in to the Alipay console with the account you have just registered.
Go to "Web & Mobile Apps" (网页&移动应用) tab in "My Application" (我的应用) panel.
Click "Create an App" (立即创建) button to start configuring your application.
Name your application in "Application Name" (应用名称) following the naming conventions and upload your "Application Icon" (应用图标), make sure you choose "web application" (网页应用) as "App type" (应用类型).
After finishing creating the application, we come to the Overview page, where we should click "add ability" (添加能力) to add "Third-party application authorization" (第三方应用授权), "Get member information" (获取会员信息) and "App Alipay login" (App 支付宝登录) before enabling Alipay sign-in.
Go to Alipay Customer Center, and sign in with the Alipay developer account. Click "Account Center" (账号中心) on the topbar and go to "APPID binding" (APPID 绑定), whose entrance can be found at the bottom of the sidebar. "Add binding" (添加绑定) by type in the APPID of the web application you just created in step 4.
Click on "Sign" button of "App Alipay login", and finish signing process following the guide. After finishing this step, you are expected to find abilities you have just added in step 5 kicks in.
Come back to Alipay open platform console page, and you can find "Interface signing method" (接口加签方式（密钥/证书）) in "development information" (开发信息) section. Click "set up" (设置) button, and you can find yourself on a page setting signing method. "Public Key" (公钥) is the preferred signing mode, and fill in contents from the public key file you have generated in the text input box.
Set up "Authorization Redirect URI" (授权回调地址) by clicking "set up" (设置) button on the bottom of the Alipay console page. ${your_logto_origin}/callback/${connector_id} is the default redirect URI used in Logto core. The connector_id can be found on the top bar of the Logto Admin Console connector details page.
After finishing all these steps, go back to the top right corner of Alipay console page, and click "Submit for review" (提交审核). Once the review is approved, you are good to go with a smooth Alipay sign-in flow.

note:

You can use openssl to generate key pairs on your local machine by executing following code snippet in terminal.

openssl genrsa -out private.pem 2048
openssl rsa -in private.pem -outform PEM -pubout -out public.pem

When filling in the public key on the Alipay app setup website, you need to remove the header and footer of public.pem, delete all newline characters, and paste the rest of the contents into the text input box for "public key".

Set up the Logto Alipay Web connector settings

In the Alipay console workspace go to "My application" (我的应用) panel and click "Web & Mobile Apps" (网页&移动应用) tab, you can find APPID of all applications.
In step 7 of the previous part, you have already generated a key pair including a private key and a public key.
Fill out the Logto connector settings:
- Fill out the appId field with APPID you've got from step 1.
- Fill out the privateKey field with contents from the private key file mentioned in step 2. Please MAKE SURE to use '\n' to replace all newline characters and do not remove header and footer in private key file.
- Fill out the signType field with 'RSA2' due to the Public key signing mode we chose in step 7 of "Create And Configure Alipay Apps".
- Fill out the charset field with either 'gbk' or 'utf8'. You can leave this field blank as it is OPTIONAL. The default value is set to be 'utf8'.
- Fill out the scope field with either 'auth_base' or 'auth_user'. You can leave this field blank as it is OPTIONAL. The default value is set to be 'auth_user'. You can check out the difference between different values.

Config types

Name	Type	Enum values
appId	string	N/A
privateKey	string	N/A
signType	enum string	'RSA' \| 'RSA2'
charset	enum string (OPTIONAL)	'gbk' \| 'utf8' \| undefined
scope	enum string (OPTIONAL)	'auth_user' \| 'auth_base'

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 Alipay (Web) connector should be available now.

Once you create a social connector successfully, you can enable it as a "Continue with Alipay (Web)" button in Sign-in Experience.

Navigate to Console > Sign-in experience > Sign-up and sign-in.
(Optional) Choose "Not applicable" for sign-up identifier if you need social login only.
Add configured Alipay (Web) connector to the "Social sign-in" section.

Testing and Validation

Return to your Go app. You should now be able to sign in with Alipay (Web). Enjoy!

Create an application in Logto​

Integrate Go with Logto​

Installation​

Create a session storage​

Init LogtoClient​

Implement sign-in route​

Implement the callback route​

Implement sign-out route​

Checkpoint: Test your application​

Add Alipay (Web) connector​

Set up Alipay web app​

Register Alipay developer account​

Create and configure Alipay app​

Set up the Logto Alipay Web connector settings​

Config types​

Save your configuration​

Enable Alipay (Web) connector in Sign-in Experience​

Testing and Validation​

Further readings​

Create an application in Logto

Integrate Go with Logto

Installation

Create a session storage

Init LogtoClient

Implement sign-in route

Implement the callback route

Implement sign-out route

Checkpoint: Test your application

Add Alipay (Web) connector

Set up Alipay web app

Register Alipay developer account

Create and configure Alipay app

Set up the Logto Alipay Web connector settings

Config types

Save your configuration

Enable Alipay (Web) connector in Sign-in Experience

Testing and Validation

Further readings