bug: SSO userinfo request is using HTTP POST method

[wvandeun]

Component

API Server / GraphQL

Infrahub version

1.0.2

Current Behavior

The userinfo request during the OAUTH2 and OIDC process is sent using an HTTP POST.
Some authorization servers only support this using a HTTP GET request.

According to the spec, both methods are supported and it is recommended to use HTTP GET:
https://openid.net/specs/openid-connect-core-1_0.html#UserInfoRequest

When we send the userinfo request using an HTTP POST to a server that only supports this using an HTTP GET, we will get back an HTTP 404 response. This response will not contain a JSON payload, which will cause an exception to be raised:

infrahub/backend/infrahub/api/oauth2.py

Line 123 in 136bdd7

body=response.json(),

Expected Behavior

Support calling the userinfo endpoint using the HTTP GET method

Steps to Reproduce

Configure an SSO authorization server that only supports the userinfo request using HTTP GET in Infrahub.

Additional Information

No response