So connecting to Viya via an external client....
That is really a three step process (0, 1, 2)
Step 0: Done by an administrator. They register a new 'client' with the Oauth Server known as SASLogon this requires a console token, an id (what you want your app to be known as), and a priveate key (password)
Once this is completed the Oauth server know knows that some named client can connect with some passphrase
This is normally done only once per client, then the admin has to share this id,password with the end users who would need to connect.
Step 1: You try to authenticate from a client.
So this would be you in Python, trying to connect to SASViya to authenticate and get an Oauth token that can then be leveraged in API or CAS connections. This also requires that you send a client id,password so that the Oauth server knows that the requires is coming from a valid source.
Step 2: Using your Oauth token to connect to a secure resource.
So that that you have authenticated to SASLogon and gotten an oauth token back, you can leverage that token to connect to secure resources like CAS or API endpoints. However you might not be authorized for some resources, but that is another post entirely.
This is broken down really well here with examples: https://developer.sas.com/reference/auth/
In this example they create a new registered client in the Oauth server called 'app', with some "client_secret" (the password/key/whatever you want to call it)
Then they use that to authenticate to Viya with
curl -X POST "https://server.example.com/SASLogon/oauth/token" \
-H "Content-Type: application/x-www-form-urlencoded" \
-d "grant_type=password&username=<user-id>&password=<password>" \
-u "app:mysecret"
Where they use -u on the post with the 'app:password' that was registered in what I would call step 0. And what they get back is the oauth token they then leverage in an API call or CAS connection
