Category: Flask authentication and authorization

Flask authentication and authorization

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I need to understand how flask authenticating works.

I have not found much information on the subject. Is there a complete tutorial on how to roll your own solution?

If not, I certainly would like to hear some thoughts on how you would approach it for a a flask app. I just thought about it. I also need to open a real API.

flask authentication and authorization

How do i secure that part of the app? I would suggest using the flask-login extension, it makes session management really easy to add to your flask application, and provides a nice documentation which covers in details every aspect of the extension.

Here are some snippets for basic HTTP authentication and authentication with some third-party providers. Otherwise you will need to roll your own or use a framework that has this baked in like Django. Here is a discussion thread on this topic with a useful link.

Flask-Login doesn't, technically, do authentication - it does session management, leaving the tricky to securely implement authentication details to you. Learn more. Flask user authentication Ask Question. Asked 8 years, 8 months ago. Active 9 months ago.

Flask: Basic authentication

Viewed 39k times.Depending on the type of application you're creating, you could use sessions or tokens. The information stored when doing authentication in a Flask app is usually something that we can use to identify the user for whom we generated the JWT.

That last point is important. When we receive a JWT we know to be valid, we know we generated it for a specific user. We can check this using the information stored inside the JWT. Since we know the user sent us the JWT that we generated when they logged in, we can treat this used as a "logged in user".

Learning one will make learning the other very straightforward. You also need to define app. We also have an import for authenticate and identity. That means that the simple app in that code already has an endpoint that users can access. The authenticate function is used to authenticate a user. That means, when a user gives us their username and password, what data we want to put into the JWT.

Remember, the data we put into the JWT will come back to us when the user sends it with each request. Usually in the authenticate function I check the validity of a user's username and password, and then tell Flask-JWT to store the user's id inside the JWT.

My authenticate function accepts a username and password. It then goes into the database and finds a user matching that username, and checks the password is correct. You can change which property gets stored in the JWT by setting an app configuration property.

They will do this by adding a header to their request:. Data stored inside a JWT is called a "payload", so our identity function accepts that payload as a parameter:. The payload['identity'] contains the user's id property that we saved into the JWT when we created it. The payload also contains other things, such as when the token was created, when it expires, and more.

For more information, read the "Payload" section of this post. Since payload['identity'] is the user's id —we use that to find the user in the database and return it. Here's a simple apptaken from the official documentation, that you can use to test your Flask-JWT requests. I would recommend testing different scenarios with Flask-JWT to check what it can return you.

For example, what happens if:. For example, it allows for token refreshing. If you sign up to our mailing list below, that's the best way to get access to a discount code—we share them every month with our subscribers!Flask is my favorite Python web framework. I love almost everything about Flask development, with one exception: user management.

User management in Flask, just like in many other web frameworks, is difficult. Even awesome libraries like Flask-Login and Flask-Security can be difficult to setup and maintain over long periods of time as your requirements change.

Okta is a free-to-use API service that stores user accounts, and makes handling user authentication, authorization, social login, password reset, etc. Okta utilizes open standards like OpenID Connect to make integration seamless. The first thing you need to do is copy down the Org URL from the top-right portion of your Okta dashboard page.

This URL will be used to route to your authorization server, communicate with it, and much more. Okta allows you to store and manage users for multiple applications you might be creating. This means that before we can go any further, you need to create a new OpenID Connect application for this project.

Applications in OpenID Connect have a username and password referred to as a client ID and client secret that allow your authorization server to recognize which application is talking to it at any given time. To create a new application browse to the Applications tab and click Add Application. To create an authentication token click the API tab at the top of the page followed by the Create Token button. Give your token a name, preferably the same name as your application, then click Create Token.

Once your token has been created, copy down the token value as you will need it later. The last piece of setup you need to complete is to enable user registration functionality for the authorization server. Normally, authorization servers only support login, logout, and stuff like that. Hover over that button and select the Classic UI menu option that appears. Next, hover over the Directory tab at the top of the page then select the Self-Service Registration menu item.

On this page click the Enable Registration button. The first thing you need to do in order to initialize your Flask app is install all of the required dependencies. NOTE : I also strongly recommend you get familiar with pipenv when you get some time. As you can see from the small file above, building a minimalist app with Flask can be really simple.

All you need to do is:. The next step to building a simple Flask app is creating a homepage and dashboard page. To get started, open up you app. Templates in Flask are built using the Jinja2 templating language.

Login authentication with Flask

All templates in Flask should live inside the templates folder. This layout. The block Jinja2 tag allows us to inject content from a child template into this parent template.

This is what lets us build complex HTML pages without writing redundant code. Everything inside the block tags is then injected back into the parent template from before. This template works in the same way, except it also outputs some variables.

These variables will eventually be available once we hook up the OpenID Connect library.Authentication is the mechanism whereby systems may securely identify their users. OAuth2 integration is easily accomplished. Authorization is the mechanism by which a system determines what level of access a particular authenticated user should have access to resources controlled by the system.

In Eve, you can restrict access to all API endpoints, or only some of them. You can protect some HTTP verbs while leaving others open.

flask authentication and authorization

For example, you can allow public read-only access while leaving item creation and edition restricted to authorized users only. There is also support for role-based access control. Security is one of those areas where customization is very important.

Flask & Python Authentication & Authorization - RTask Day 3

This is why you are provided with a handful of base authentication classes. They implement the basic authentication mechanism and must be subclassed in order to implement authorization logic.

To enable authentication for your API just pass the custom auth class on app instantiation. All your API endpoints are now secured, which means that a client will need to provide the correct credentials in order to consume the API:.

But what if your authorization logic is more complex, and you only want to secure some endpoints or apply different logics depending on the endpoint being consumed? You could get away with just adding logic to your authentication class, maybe with something like this:. This way the global level auth class, the one passed to the Eve constructor as seen above, would still be active on all endpoints except those where different authorization logic is needed.

Alternatively, we could even choose to not provide a global auth class, effectively making all endpoints public, except the ones we want protected. With a system like this we could even choose to have some endpoints protected with, say, Basic Authentication while others are secured with Token, or HMAC Authentication!

Well, turns out this is actually possible by simply enabling the resource-level authentication setting when we are defining the API domain. The people endpoint will now be using the MySuperCoolAuth class for authentication, while the invoices endpoint will be using the general-purpose auth class if provided or else it will just be open to the public. There are other features and options that you can use to reduce complexity in your auth classes, especially but not only when using the global level authentication system.

Lets review them. You might want a public read-only API where only authorized users can write, edit and delete. Add the following to your settings. And run your API. Suppose that you want to allow public read access to only certain resources. You do that by declaring public methods at resource level, while declaring the API domain :. Be aware that, when present, resource settings override global settings.

You can use this to your advantage. You first open read access for all endpoints:. The eve. It should be subclassed in order to implement custom authentication. Encoding passwords with bcrypt is a great idea. This script assumes that user accounts are stored in an accounts MongoDB collection, and that passwords are stored as bcrypt hashes.Its good practice to time out logged in session after specific time, you can achieve that with Flask-Login.

Default session lifetime is 31 days, user need to specify the login refresh view in case of timeout. One of the simpler ways of implementing an authorization system is using the flask-login extension. The project's website contains a detailed and well-written quickstart, a shorter version of which is available in this example. I would recommend to place all auth related code in a separate module or package, for example auth.

That way you can create the necessary classes, objects or custom functions separately. The extension uses a LoginManager class which has to be registered on your Flask application object. As mentioned earlier LoginManager can for example be a global variable in a separate file or package.

Then it can be imported in the file in which the Flask object is created or in your application factory function and initialized. A users will normally be loaded from a database. The callback must return an object which represents a user corresponding to the provided ID.

It should return None if the ID is not valid. What does that mean exactly? That object can for example be a wrapper around user objects stored in your database or simply directly a model from your database.

That object has to implement the following methods and properties. That means that if the callback returns your database model you need to ensure that the mentioned properties and methods are added to your model.

This property should return True if the user is authenticated, i. This property should return True if this is an active user - in addition to being authenticated, they also have activated their account, not been suspended, or any condition your application has for rejecting an account. Inactive accounts may not log in. If you don't have such a mechanism present return True from this method. This property should return True if this is an anonymous user.

flask authentication and authorization

Note that this must be a unicode - if the ID is natively an int or some other type, you will need to convert it to unicode.

You can see how those methods and properties are implemented by default in this mixin here. The extension leaves the validation of the username and password entered by the user to you. In fact the extension doesn't care if you use a username and password combo or other mechanism. This is an example for logging users in using username and password.

As shown this will usually happen after retrieving the user from the database and validating his credentials, however the user object just magically appears in this example. By defult an AnonymousUserMixin is returned:. To use a different object for anonymous users provide a callable either a class or factory function that creates anonymous users to your LoginManager with:.

This concludes the basic introduction to the extension. To learn more about configuration and additional options it is highly recommended to read the official guide. Flask Pedia. Tutorial Knowledge-Base Awesome. Authorization and authentication Timing out the login session Its good practice to time out logged in session after specific time, you can achieve that with Flask-Login. General idea The extension exposes a set of functions used for: logging users in logging users out checking if a user is logged in or not and finding out which user is that What it doesn't do and what you have to do on your own: doesn't provide a way of storing the users, for example in the database doesn't provide a way of checking user's credentials, for example username and password Below there is a minimal set of steps needed to get everything working.

Create a LoginManager The extension uses a LoginManager class which has to be registered on your Flask application object. Specify a callback used for loading users A users will normally be loaded from a database. Logging the users in The extension leaves the validation of the username and password entered by the user to you.In this tutorial you will learn how to build a login web app with Python using Flask.

The first one displays the login screen or the home screen, based on the condition if you are logged in. The second route validates the login variables on login. If all of these terms are unfamiliar to you, just keep reading. This file will create the database structure.

Inside the directory you will find a file called tutorial. Create a file called dummy. Validating the login credentials with SqlAlchemy The next step is to write the functionality that validates the user and password exist in the database. We map the objects to relational database tables and vice versa. The definition User is given in tabledef.

The s. We have two conditions: the username and password must match. The query. This gives us this total code:. Download Flask Examples. Hash your database passwords. Log the failed login attempts. Building a Flask login screen Create this Python file and save it as app.

Simple JWT Authentication with Flask-JWT

We picked a random login template from codepen. As you may have seen, there is no logout button or functionality. Creating that is very easy. The solution proposed below is only one of the many solutions. This function clears the session variable and returns to the login screen. Flask does not have out of the box database support.

You have to use a third party library if you want database support. In this tutorial we will use SqlAlchemy. Create the file tabledef.

Finally we update our app. What about security? We have demonstrated a simple login app above. However, it is your job to properly secure it. There are many guys out there that are going to try to break into your app.

Download Flask Examples Best practices: Hash your database passwords. Posted in Flask.Many web sites offer users the option to use a streamlined single-click registration and login built on third party authentication services, typically run by the big social networks. In this article I want to give you an introduction to the OAuth protocol, which these days has replaced OpenID as the preferred third party authentication mechanism.

With these two implementations as a guide you should find it easy to add any other OAuth providers you may need. The best way to explain OAuth is by going over the list of events that occur during the sign in process:.

You can see above that the exchange between the application and the third party service is not trivial, but for the user it is extremely simple, since all the user needs to do is log in to the third party site and give permission to share information with the application.

There are two versions of the OAuth protocol currently in use, both following the overall process described above but with some implementation differences.

OAuth 1. OAuth 2, used by Facebook, is a backwards incompatible revision of the protocol that eliminates much of the complexity of version 1. Before an application can use a third party OAuth provider it needs to register with it.

For Facebook and Twitter this is done on their respective developer sites with the creation of an "app" that represents the application for users of these sites. Then enter a name and category for your app. You will be asked to provide the app name, description, website and callback URL. Note: If you want to use other OAuth providers you will need to find the appropriate procedure to register an application in their developer documentation.

The newly created app will be assigned two codes, usually called "id" and "secret". These identify the application that is making the authentication request, and are passed in the query string of the redirect URL to the provider site, in step 2 above. In the following sections I'm going to describe a relatively simple Flask application that implements Facebook and Twitter authentication. At the end of this article I show you the instructions on how to run it.

The users of the example application are stored in a SQLAlchemy database. The application uses the Flask-SQLAlchemy extension to work with the database, and the Flask-Login extension to keep track of logged in users.

The database has a single table for the users. In addition to the id that is the primary key, the users table contains three columns:. The model also inherits from UserMixin from Flask-Login, as that gives it the methods required by that extension. There are several OAuth client packages for Python.

For this example I have decided to use Rauth. But even when using an OAuth package, there are many aspects of the authentication against OAuth service providers that are left up to each provider to implement, which makes the task harder. First of all, there are the two versions of the OAuth protocol, both widely used.

But even among different providers using the same OAuth version, there are many details that are not part of the specification and need to be done according to the provider's own documentation. For this reason I have decided to implement an abstraction layer on top of Rauth, so that the Flask application can be written generically. Below you can see a simple base class under which the provider specific implementations will be written:.

The OAuthSignIn base class defines the structure that the subclasses that implement each provider must follow. The constructor initializes the provider's name, and the application id and secret assigned by it, which are obtained from the configuration.

Below you can see how the example application is configured of course you will need to replace these codes with your own when you try this application :.

At a high level there are two significant events supported by this class that are common to all OAuth providers:. This method uses introspection to find all the OAuthSignIn subclasses, and then saves an instance of each in a dictionary. I create an object of this class in each provider's OAuthSignIn subclass.

The implementations for Facebook and Twitter are shown below:. The service object is initialized with the name of the service and several OAuth specific arguments. Twitter implements OAuth 1.


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