How to build Kakao sign-in with Python

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 Kakao sign-in experience (user authentication) with Python and Logto.

Prerequisites

A running Logto instance. Check out the introduction page to get started.
Basic knowledge of Python.
A usable Kakao 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 "Flask" 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 Flask SDK

tip:

The example uses Flask, but the concepts are the same for other frameworks.
The Python sample project is available on our Python SDK repo.
Logto SDK leverages coroutines, remember to use await when calling async functions.

Installation

Execute in the project root directory:

pip install logto # or `poetry add logto` or whatever you use

Init LogtoClient

First, create a Logto config:

client.py
from logto import LogtoClient, LogtoConfig

client = LogtoClient(
    LogtoConfig(
        endpoint="https://you-logto-endpoint.app",  # Replace with your Logto endpoint
        appId="replace-with-your-app-id",
        appSecret="replace-with-your-app-secret",
    ),
)

tip:

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

Also replace the default memory storage with a persistent storage, for example:

client.py
from logto import LogtoClient, LogtoConfig, Storage
from flask import session
from typing import Union

class SessionStorage(Storage):
    def get(self, key: str) -> Union[str, None]:
        return session.get(key, None)

    def set(self, key: str, value: Union[str, None]) -> None:
        session[key] = value

    def delete(self, key: str) -> None:
        session.pop(key, None)

client = LogtoClient(
    LogtoConfig(...),
    storage=SessionStorage(),
)

See Storage for more details.

In your web application, add a route to properly handle the sign-in request from users. Let's use /sign-in as an example:

flask.py
@app.route("/sign-in")
async def sign_in():
  # Get the sign-in URL and redirect the user to it
  return redirect(await client.signIn(
      redirectUri="http://localhost:3000/callback",
  ))

Replace http://localhost:3000/callback with the callback URL you set in your Logto Console for this application.

If you want to show the sign-up page on the first screen, you can set interactionMode to signUp:

flask.py
@app.route("/sign-in")
async def sign_in():
  return redirect(await client.signIn(
      redirectUri="http://localhost:3000/callback",
      interactionMode="signUp", # Show the sign-up page on the first screen
  ))

Now, whenever your users visit http://localhost:3000/sign-in, it will start a new sign-in attempt and redirect the user to the Logto sign-in page.

Note Creating a sign-in route isn't the only way to start a sign-in attempt. You can always use the signIn method to get the sign-in URL and redirect the user to it.

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

To clean up the Python session and Logto session, a sign-out route can be implemented as follows:

flask.py
@app.route("/sign-out")
async def sign_out():
  return redirect(
      # Redirect the user to the home page after a successful sign-out
      await client.signOut(postLogoutRedirectUri="http://localhost:3000/")
  )

Handle authentication status

In Logto SDK, we can use client.isAuthenticated() to check the authentication status, if the user is signed in, the value will be true, otherwise, the value will be false.

Here we also implement a simple home page for demonstration:

If the user is not signed in, show a sign-in button;
If the user is signed in, show a sign-out button.

@app.route("/")
async def home():
    if client.isAuthenticated() is False:
        return "Not authenticated <a href='/sign-in'>Sign in</a>"
    return "Authenticated <a href='/sign-out'>Sign out</a>"

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 Kakao connector

To enable quick sign-in and improve user conversion, connect with Flask 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 "Kakao".
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 Kakao login

Set up a project in the Kakao Devlopers Console

Visit the Kakao Developers Console and sign in with your Kakao account.
Click the Add an application to create new project or choose exist project.

Click the Product Settings -> Kakao Login from the menu.
Turn on Kakao Login Activation
Add below URL into Redirect URI
- http(s)://YOUR_URL/callback/${connector_id} (The connector_id can be found on the top bar of the Logto Admin Console connector details page.)
- (Please replace YOUR_URL with your Logto URL, and choose http or https on your situation.)

Privacy Setting

Click the Product Settings -> Kakao Login -> Consent Item from the menu.
Change state of Nickname, Profile image, and Email to Required consent (You might not able to change Email to Required consent because of your project setting.)

Security Setting (Optional)

Click the Product Settings -> Kakao Login -> Security from the menu.
Click the Client secret code to generate secret code.
Change Activation state to Enable. (If you enable it, secret code is necessary.)

Configure Logto

Config types

Name	Type
clientId	string
clientSecret	string?

clientId

clientId is REST API key of your project. (You can find it from summary of your project from Kakao developers console.)

clientSeceret

clientSecret is Secret Code of your project. (Please check Security Setting (Optional))

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 Kakao connector should be available now.

Once you create a social connector successfully, you can enable it as a "Continue with Kakao" 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 Kakao connector to the "Social sign-in" section.

Sign-in Experience tab

Testing and Validation

Return to your Python app. You should now be able to sign in with Kakao. Enjoy!

Create an application in Logto​

Integrate Flask SDK​

Installation​

Init LogtoClient​

Implement sign-in and sign-out​

Handle authentication status​

Checkpoint: Test your application​

Add Kakao connector​

Set up Kakao login​

Set up a project in the Kakao Devlopers Console​

Configure Kakao Login​

Activate Kakao Login​

Privacy Setting​

Security Setting (Optional)​

Configure Logto​

Config types​

clientId​

clientSeceret​

Save your configuration​

Enable Kakao connector in Sign-in Experience​

Testing and Validation​

Further readings​