Quickstart

This section covers basic installation and usage of the PyCAS-SSO library.

Requirements

  • Python 3.10 or newer.

Installation

First step is to install the library.

Note

It’s highly recommended to use Python virtual env..

Using PyPi

Installing PyCAS-SSO from PyPi is the easiest way to install the library.

  • In your Python venv :

pip install pycas-sso[httpx]

It will install PyCAS-SSO alongside the HTTPX library. The HTTPX library is the default choice for PyCAS-SSO because it supports both synchronous and asynchronous programming.

If you want to use another HTTP client with PyCAS-SSO refer to the list of supported library below.

Supported HTTP Clients

Client

Synchronous

Asynchronous

Installation

requests

✅

❌

pip install pycas-sso[requests]

httpx

✅

✅

pip install pycas-sso[httpx]

aiohttp

❌

✅

pip install pycas-sso[aiohttp]

From Git Repository

  • To install the library manually in your project, download the latest release from GitHub.

  • Extract the archive and copy the pycas_sso folder into your project folder.

  • Install the library dependencies from the requirements.txt file.

pip install -r requirements.txt

  • Finally install httpx or another supported HTTP client using pip.

pip install httpx

Basic Usage

The common uses of CAS are:

  • Check if a user is authenticated on a service, and if not, redirect them to the CAS login page;

  • After user sign-in, they will be redirected to the service with a ticket included in the callback URL;

  • The service validates the ticket with the CAS service and then marks the user as authenticated if successful.

Start a CAS Client

Let’s get started. First we need to instantiate a CAS client using pycas_sso.cas.CASClient.create.

from pycas_sso.cas import CASClient

# URL of your CAS service
provider = "https://cas.example.com"

# URL of your service
# Note: don't forget to authorize this url on your CAS service
service = "https://service.example.com/"

# Callback URL of you service
# This is the URL where user will be redirect after sign-in
callback = "https://service.example.com/login"

if __name__ == "__main__":
    # Use Python ContextManager with CASClient.create
    with CASClient.create(provider, service, callback) as client:
        pass

pycas_sso.cas.CASClient.create will return a pycas_sso.clients.core.CASClientBase instance depending on your HTTP client. You can force the HTTP client by specifying the http_lib parameter (e.g., http_lib = 'requests'), otherwise it will search for a supported HTTP library that is installed and use it.

If you want to use asynchronous operations:

import asyncio
from pycas_sso.cas import CASClient

...

async def main():
    async with CASClient.create(provider, service, callback, is_async = True) as client:
        pass

if __name__ == "__main__":
    asyncio.run(main())

Don’t forget the is_async = True parameter.

Get Login Page URL

To retrieve the login page URL, use pycas_sso.clients.core.CASClientBase.login_form_url.

with CASClient.create(provider, service, callback) as client:
    login_url = client.login_form_url()

Extract Service Ticket from URL

To extract ticket from a URL you just need to pass the URL to pycas_sso.clients.core.CASClientBase.ticket_from_url.

url = "https://service.example.com/login?ticket=ST-123456-789"

with CASClient.create(provider, service) as client:
    ticket = client.ticket_from_url(url) # ticket = "ST-123456-789"

Validate the Service Ticket

Validating the ticket allows verification of the ticket with the CAS service and retrieval of user information. To achieve this, we will use pycas_sso.clients.core.CASClientBase.service_validate.

from pycas_sso.errors import CASServiceAuthenticationFailure

ticket = "ST-123456-789"

with CASClient.create(provider, service, callback) as client:
    try:
        data = client.service_validate(ticket)
        print(f"Validation succeeded\nUsername: {data.username}")
    except CASServiceAuthenticationFailure as err:
        print(err)

Or with asynchronous:

...

async with CASClient.create(provider, service, callback) as client:
    try:
        data = await client.aservice_validate(ticket)
        print(f"Validation succeeded\nUsername: {data.username}")
    except CASServiceAuthenticationFailure as err:
        print(err)

Tip

Use the version='2|3' parameter to specify which version of the CAS protocol to use when performing a service validation call.

You can also use:

Go Further