admin.py

from django.contrib.admin import AdminSite
from django.http import HttpResponseRedirect
from django.urls import reverse
from django.views.decorators.cache import never_cache


class CustomAdminSite(AdminSite):
    @never_cache
    def login(self, request, extra_context=None):
        if request.method == 'GET' and self.has_permission(request):
            # Already logged-in, redirect to admin index
            index_path = reverse('admin:index', current_app=self.name)
            return HttpResponseRedirect(index_path)
        else:
            login_path = reverse('oidc_authentication_init')
            return HttpResponseRedirect(login_path)

apps.py

from django.contrib.admin.apps import AdminConfig


class CustomAdminConfig(AdminConfig):
    default_site = 'admin.admin.CustomAdminSite'

LICENSE

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License for https://gist.github.com/dmptrluke/792781d52e4c294f018cdf17ca8cf18b/

Zero-Clause BSD

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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