Globus `identity_provider` restriction ignored when used with `allow_all` in JupyterHub 5.0

Impact

JupyterHub < 5.0, when used with GlobusOAuthenticator, could be configured to allow all users from a particular institution only. The configuration for this would look like:

# Require users to be using the "foo.horse" identity provider, often an institution or university
c.GlobusAuthenticator.identity_provider = "foo.horse"
# Allow everyone who has that identity provider to log in
c.GlobusAuthenticator.allow_all = True

This worked fine prior to JupyterHub 5.0, because allow_all did not take precedence over identity_provider.

Since JupyterHub 5.0, allow_all does take precedence over identity_provider. On a hub with the same config, now all users will be allowed to login, regardless of identity_provider. identity_provider will basically be ignored.

This is a documented change in JupyterHub 5.0,
but is likely to catch many users by surprise.

Patches

OAuthenticator 16.3.1 fixes the issue with JupyterHub 5.0, and does not affect previous versions.

Workarounds

Do not upgrade to JupyterHub 5.0 when using GlobusOAuthenticator in the prior configuration.