auth: Add social_backends to /server_settings.

zerver/openapi/zulip.yaml

@@ -2099,6 +2099,11 @@ paths:
                       description: Each key-value pair in the object indicates
                         whether the authentication method is enabled on this
                         server.
+                    social_backends:
+                      type: array
+                      description: List of "social backend" objects, describing which
+                        social backends are enabled and their parameters - most importantly
+                        the login url, display_name and display_logo.
                     zulip_version:
                       type: string
                       description: The version of Zulip running in the server.

zerver/tests/test_auth_backends.py

@@ -33,7 +33,7 @@ from zerver.lib.avatar_hash import user_avatar_path
 from zerver.lib.dev_ldap_directory import generate_dev_ldap_dir
 from zerver.lib.mobile_auth_otp import otp_decrypt_api_key
 from zerver.lib.validator import validate_login_email, \
-    check_bool, check_dict_only, check_string, Validator
+    check_bool, check_dict_only, check_list, check_string, Validator
 from zerver.lib.request import JsonableError
 from zerver.lib.storage import static_path
 from zerver.lib.users import get_all_api_keys
@@ -57,7 +57,8 @@ from zproject.backends import ZulipDummyBackend, EmailAuthBackend, \
     require_email_format_usernames, AUTH_BACKEND_NAME_MAP, \
     ZulipLDAPConfigurationError, ZulipLDAPExceptionOutsideDomain, \
     ZulipLDAPException, query_ldap, sync_user_from_ldap, SocialAuthMixin, \
-    PopulateUserLDAPError, SAMLAuthBackend, saml_auth_enabled, email_belongs_to_ldap
+    PopulateUserLDAPError, SAMLAuthBackend, saml_auth_enabled, email_belongs_to_ldap, \
+    get_social_backend_dicts
 
 from zerver.views.auth import (maybe_send_to_registration,
                                _subdomain_token_salt)
@@ -1836,10 +1837,12 @@ class FetchAuthBackends(ZulipTestCase):
             ]
             for backend_name_with_case in AUTH_BACKEND_NAME_MAP:
                 authentication_methods_list.append((backend_name_with_case.lower(), check_bool))
+            social_backends = get_social_backend_dicts()
 
             self.assert_json_success(result)
             checker = check_dict_only([
                 ('authentication_methods', check_dict_only(authentication_methods_list)),
+                ('social_backends', check_list(None, length=len(social_backends))),
                 ('email_auth_enabled', check_bool),
                 ('is_incompatible', check_bool),
                 ('require_email_format_usernames', check_bool),

zerver/views/auth.py

@@ -847,7 +847,8 @@ def api_get_server_settings(request: HttpRequest) -> HttpResponse:
             "realm_uri",
             "realm_name",
             "realm_icon",
-            "realm_description"]:
+            "realm_description",
+            "social_backends"]:
         if context[settings_item] is not None:
             result[settings_item] = context[settings_item]
     return json_success(result)