How to Use Refresh Token With Fastapi in 2024?

To use a refresh token with FastAPI, you first need to set up an authentication system that includes both access tokens and refresh tokens. Access tokens are short-lived tokens used to access protected resources, while refresh tokens are used to obtain new access tokens when the current one expires.

In FastAPI, you can implement this by creating endpoints for login (which will generate both access and refresh tokens), refresh (which will request a new access token using a refresh token), and protected resources (which will require a valid access token to access).

You can store refresh tokens in a database or another secure data store, along with the user they are associated with and their expiration date. When a user requests a new access token using a refresh token, you can verify the refresh token against the stored tokens and issue a new access token if it is valid.

By implementing a robust authentication system with access and refresh tokens in FastAPI, you can ensure the security and reliability of your application while providing a seamless user experience.

How to handle token invalidation and revocation in FastAPI?

To handle token invalidation and revocation in FastAPI, you can use various strategies such as token blacklisting, token expiration, or token revocation lists.

Token Blacklisting: One common strategy is to maintain a blacklist of revoked tokens in your application. When a token is issued, you can store the token's unique identifier (such as the JWT token's "jti" claim) in a blacklist. Before processing a request with a token, you can check if the token's identifier exists in the blacklist to determine if it has been revoked.

Here's an example of how you can implement token blacklisting in FastAPI:

from fastapi import HTTPException, Depends
from fastapi.security import OAuth2PasswordBearer
from jose import jwt, JWTError

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/token")
blacklisted_tokens = set()

def is_token_blacklisted(token: str):
    try:
        payload = jwt.decode(token, "secret_key", algorithms=["HS256"])
        token_id = payload.get("jti")
        return token_id in blacklisted_tokens
    except JWTError:
        return False

def get_current_user(token: str = Depends(oauth2_scheme)):
    if is_token_blacklisted(token):
        raise HTTPException(status_code=401, detail="Token has been revoked")
    
    # Verify and decode token to get current user
    try:
        payload = jwt.decode(token, "secret_key", algorithms=["HS256"])
        user_id = payload.get("sub")
        return user_id
    except JWTError:
        raise HTTPException(status_code=401, detail="Invalid token")

Token Expiration: Another common approach is to set an expiration time for tokens. Once a token expires, it can no longer be used to access protected resources. You can include the expiration time in the token payload and check if the token has expired before processing the request.

from datetime import datetime

def is_token_expired(token: str):
    try:
        payload = jwt.decode(token, "secret_key", algorithms=["HS256"])
        expiration_time = payload.get("exp")
        return datetime.utcfromtimestamp(expiration_time) < datetime.utcnow()
    except JWTError:
        return True

Token Revocation Lists: You can also maintain a list of revoked tokens in a database or cache to manage token revocation. When a user logs out or changes their password, you can add the token to the revocation list to invalidate it.

from fastapi import HTTPException

def revoke_token(token_id: str):
    blacklisted_tokens.add(token_id)

def is_token_revoked(token: str):
    try:
        payload = jwt.decode(token, "secret_key", algorithms=["HS256"])
        token_id = payload.get("jti")
        return token_id in blacklisted_tokens
    except JWTError:
        return False

By implementing these strategies, you can effectively handle token invalidation and revocation in your FastAPI application to enhance security and protect sensitive data.

What is the impact of using refresh tokens on API performance in FastAPI?

Using refresh tokens in FastAPI can have a slight impact on API performance, as the process of requesting and validating a new access token (using the refresh token) adds an extra step in the authentication process. This can increase the overall response time for API requests that require authentication.

However, this impact is typically minimal and is outweighed by the security benefits of using refresh tokens to securely manage access to your API. Refresh tokens help mitigate security risks by limiting the lifetime of access tokens and allowing for more granular control over when and how users can access your API.

Overall, the impact of using refresh tokens on API performance in FastAPI is generally minor and the added security benefits make it a worthwhile tradeoff.

How to use refresh tokens for long-lived sessions in FastAPI?

To use refresh tokens for long-lived sessions in FastAPI, you can follow these steps:

Define a refresh token model: Create a Pydantic model to represent the refresh token data. This model should include fields such as token, user_id, expiration datetime, and any other relevant information.
Generate and save refresh tokens: When a user logs in or authenticates, generate a refresh token using a secure random token generator. Save this token along with the user's ID and expiration datetime in a database or cache.
Return refresh tokens to the client: After generating a refresh token, return it to the client in the response body. Make sure to securely transmit the token to the client to prevent any security vulnerabilities.
Implement token refresh endpoint: Create an API endpoint in your FastAPI application that allows clients to refresh their access tokens using a valid refresh token. This endpoint should check the provided refresh token against the stored tokens and issue a new access token if the refresh token is valid.
Verify token expiration: When a client submits a refresh token for token refresh, verify that the token has not expired before issuing a new access token. If the refresh token has expired, prompt the user to log in again.
Secure token storage: Make sure to securely store refresh tokens in your database or cache to prevent unauthorized access. Use strong encryption and hashing algorithms to protect the token data.

By following these steps, you can effectively implement refresh tokens for long-lived sessions in FastAPI and provide a secure authentication mechanism for your application.

How to handle token expiration and invalidation in FastAPI?

In FastAPI, you can handle token expiration and invalidation by implementing token validation logic in your authentication middleware. Here are steps to handle token expiration and invalidation in FastAPI:

Implement token validation logic: Create a middleware function that checks the validity of the token provided by the user in the request headers. You can use libraries like PyJWT to decode and verify JWT tokens.
Add middleware to your FastAPI application: Register the middleware function with your FastAPI application by using the app.add_middleware() method. This will ensure that the token validation logic is executed for each request before it reaches your endpoint handler functions.
Check token expiration and invalidation: In your middleware function, check if the token has expired or has been invalidated. If the token is expired or invalid, return a 401 Unauthorized response to the client.
Handle token expiration and invalidation errors: In your endpoint handler functions, catch and handle the 401 Unauthorized responses returned by the middleware function. You can provide appropriate error messages to the client or redirect them to a login page.

By following these steps, you can effectively handle token expiration and invalidation in your FastAPI application. This will help ensure the security and integrity of your authentication system.

How to store refresh tokens securely in FastAPI?

The best practice for storing refresh tokens securely in FastAPI is to use a secure and encrypted data store, such as a database or Redis, to securely store the tokens. Here are some steps to follow:

Use a secure storage solution: Avoid storing refresh tokens in plaintext in your code or in configuration files. Instead, use a secure data storage solution, such as a database like PostgreSQL or SQLite, to store the tokens securely.
Encrypt the tokens: Before storing the refresh tokens in the database, make sure to encrypt them using a strong encryption algorithm. This adds an extra layer of security to protect the tokens from unauthorized access.
Use secure authentication mechanisms: Implement secure authentication mechanisms, such as JWT (JSON Web Tokens) or OAuth, to generate and validate refresh tokens. This helps ensure that only authorized users can access the tokens.
Set proper permissions: Make sure to set proper permissions and access controls on the data store where you store the refresh tokens. Limit access to only authorized users and regularly monitor and audit access to the storage.
Rotate and expire tokens: Implement token rotation and expiration policies to regularly rotate refresh tokens and expire them after a certain period of time. This helps prevent token misuse and reduces the risk of unauthorized access.

By following these best practices, you can securely store refresh tokens in FastAPI and protect them from unauthorized access or misuse.

How to monitor and log refresh token usage in FastAPI?

To monitor and log refresh token usage in FastAPI, you can implement a custom middleware that intercepts requests and checks the validity of the refresh token. Here's an example of how you can implement this middleware:

Create a new Python file for your custom middleware, for example, refresh_token_middleware.py.
Implement the middleware by creating a class that inherits from RequestMiddleware in FastAPI.

from fastapi import Request
from fastapi.responses import JSONResponse
from fastapi.middleware.base import BaseHTTPMiddleware

class RefreshTokenMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next):
        # Check if the request has a valid refresh token
        refresh_token = request.cookies.get("refresh_token")
        if not refresh_token:
            return JSONResponse(status_code=401, content={"error": "Refresh token missing"})

        # Log the refresh token usage
        # You can log the details of the request using your preferred logging library
        print(f"Refresh token used for user: {get_user_from_refresh_token(refresh_token)}")

        # Call the next middleware or route handler
        response = await call_next(request)
        return response

Import your custom middleware in your FastAPI app and add it to the middleware stack.

from fastapi import FastAPI
from refresh_token_middleware import RefreshTokenMiddleware

app = FastAPI()

@app.get("/")
async def home():
    return {"message": "Hello, World!"}

app.add_middleware(RefreshTokenMiddleware)

Create a function get_user_from_refresh_token that extracts user information from the refresh token.

With this setup, every request that passes through the middleware will be checked for a valid refresh token. The middleware will log each usage of the refresh token.

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How to Use Refresh Token With Fastapi?