Every app needs authentication and authorization. Logto is an Auth0 alternative designed for modern apps and SaaS products.
In this article, we will go through the steps to quickly build the OAuth2 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 OAuth2 account.
Create an application in Logto
In you browser, open a new tab and enter the link of Logto Admin Console.
Once the page is loaded, in the "Get Started" section click the View all
link to open the application framework list page.
Choose your application type
In the opening modal, scroll to the "Traditional web" section or filter all the available " Traditional web" frameworks using the quick filter checkboxes on the left.
Click the "undefined" framework card to start creating your application.
Enter application name
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 Logto SDK
- 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
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.
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:
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:
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:
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:
func main() {
// ...
logtoConfig := &client.LogtoConfig{
Endpoint: "<your-logto-endpoint>", // E.g. http://localhost:3001
AppId: "<your-application-id>",
AppSecret: "<your-application-secret>",
}
// ...
}
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:
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))
})
// ...
}
Implement sign-in route
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:
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.
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:
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.
Open your Go app to test if the integration works. When you click the "Sign In" button, the page should be redirected to a Logto sign-in page, and you should be able to create a new account by entering username and password and complete the sign-in process.
Add OAuth2 connector
To add a social connector, go to the "Connector" tab in the Admin Console, then click on "Social connectors". From there, click "Add social connector".
In the openning modal, select "OAuth2" and click "Next".
On the next page, you will see a two-column layout with the README content on the left and configuration on the right.
Feel free to follow the README file in place or read the following section to complete the configuration process. If you follow the in-place guide, you can skip the next section.
Set up Standard OAuth 2.0 app
Create your OAuth 2.0 app
When you open this page, we believe you already know which social identity provider you want to connect to. The first thing to do is to confirm that the identity provider supports the OAuth 2.0 protocol, which is a prerequisite for configuring a valid connector. Then, follow the identity provider's instructions to register and create the relevant app for OAuth 2.0 authorization.
Configure your connector
We ONLY support "Authorization Code" grant type for security consideration and it can perfectly fit Logto's scenario.
clientId
and clientSecret
can be found at your OAuth 2.0 apps details page.
clientId: The client ID is a unique identifier that identifies the client application during registration with the authorization server. This ID is used by the authorization server to verify the identity of the client application and to associate any authorized access tokens with that specific client application.
clientSecret: The client secret is a confidential key that is issued to the client application by the authorization server during registration. The client application uses this secret key to authenticate itself with the authorization server when requesting access tokens. The client secret is considered confidential information and should be kept secure at all times.
scope: The scope parameter is used to specify the set of resources and permissions that the client application is requesting access to. The scope parameter is typically defined as a space-separated list of values that represent specific permissions. For example, a scope value of "read write" might indicate that the client application is requesting read and write access to a user's data.
You are expected to find authorizationEndpoint
, tokenEndpoint
and userInfoEndpoint
in social vendor's documentation.
authenticationEndpoint: This endpoint is used to initiate the authentication process. The authentication process typically involves the user logging in and granting authorization for the client application to access their resources.
tokenEndpoint: This endpoint is used by the client application to obtain an access token that can be used to access the requested resources. The client application typically sends a request to the token endpoint with a grant type and authorization code to receive an access token.
userInfoEndpoint: This endpoint is used by the client application to obtain additional information about the user, such as their fullname, email address or profile picture. The user info endpoint is typically accessed after the client application has obtained an access token from the token endpoint.
Logto also provide a profileMap
field that users can customize the mapping from the social vendors' profiles which are usually not standard. The keys are Logto's standard user profile field names and corresponding values should be social profiles' field names. In current stage, Logto only concern 'id', 'name', 'avatar', 'email' and 'phone' from social profile, only 'id' is required and others are optional fields.
responseType
and grantType
can ONLY be FIXED values with authorization code grant type, so we make them optional and default values will be automatically filled.
For example, you can find Google user profile response and hence its profileMap
should be like:
{
"id": "sub",
"avatar": "picture"
}
ℹ️ Note
We provided an OPTIONAL
customConfig
key to put your customize parameters. Each social identity provider could have their own variant on OAuth 2.0 standard protocol. If your desired social identity provider strictly stick to OAuth 2.0 standard protocol, the you do not need to care aboutcustomConfig
.
Config types
Name | Type | Required |
---|---|---|
authorizationEndpoint | string | true |
userInfoEndpoint | string | true |
clientId | string | true |
clientSecret | string | true |
tokenEndpointResponseType | enum | false |
responseType | string | false |
grantType | string | false |
tokenEndpoint | string | false |
scope | string | false |
customConfig | { [key: string]: string } | false |
profileMap | ProfileMap | false |
ProfileMap fields | Type | Required | Default value |
---|---|---|---|
id | string | false | id |
name | string | false | name |
avatar | string | false | avatar |
string | false | ||
phone | string | false | phone |
Reference
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 OAuth2 connector should be available now.
Enable OAuth2 connector in Sign-in Experience
Switch to the "Sign-in experience" tab, then click the "Sign-up and sign-in" tab.
If it's the first time you enter the tab, you will see a quick introduction about Sign-in Experience and its basic configuration.
Select "None" for the "Sign-up identifier" to provide minimum sign-up effort for OAuth2 sign-in, which may increase your conversion rate.
In the "Social sign-in" section, add "Add Social Connector" and choose "OAuth2". Then you should be able to see a button with text "Continue with OAuth2" in the preview section.
Finally, click "Save changes" on the bottom right corner.
Testing and Validation
Return to your Go app. You should now be able to sign in with OAuth2. Enjoy!
Further readings
Protect your API For native and single page apps, you'll need to call one or more API endpoints to retrieve and update data.
Learn more about identifying who's who and keeping your API secure.
User management We know you care about user management and activities, as we also do.
Learn more about how to know your users and see the figures like DAU and MAU graphically.
Localization From one regional business to a global corporate, the willingness to offer the best user experience won't change.
You can change current language phrases or add a new language without friction.
Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.