Add docs

docs/advanced_usage.md

@@ -640,3 +640,42 @@ single-sided split marker page, the split document(s) will have an empty page at
 whatever else was on the backside of the split marker page.) You can work around that by having
 a split marker page that has the split barcode on _both_ sides. This way, the extra page will
 get automatically removed.
+
+## SSO and third party authentication with Paperless-ngx
+
+Paperless-ngx has a built-in authentication system from Django but you can easily integrate an
+external authentication solution using one of the following methods:
+
+### Remote User authentication
+
+This is a simple option that uses remote user authentication made available by certain SSO
+applications. See the relevant configuration options for more information:
+[PAPERLESS_ENABLE_HTTP_REMOTE_USER](configuration.md#PAPERLESS_ENABLE_HTTP_REMOTE_USER) and
+[PAPERLESS_HTTP_REMOTE_USER_HEADER_NAME](configuration.md#PAPERLESS_HTTP_REMOTE_USER_HEADER_NAME)
+
+### OpenID Connect and social authentication
+
+Version 2.5.0 of Paperless-ngx added support for integrating other authentication systems via
+the [django-allauth](https://github.com/pennersr/django-allauth) package. Once setup, users
+can either login or (optionally) signup using any third party systems you integrate. See the
+relevant [configuration settings](configuration.md#PAPERLESS_SOCIALACCOUNT_PROVIDERS) and
+[django-allauth docs](https://docs.allauth.org/en/latest/socialaccount/configuration.html)
+for more information.
+
+As an example, to setup login via Github, the following environment variables would need to be
+set:
+
+qweqweqweq
+
+```conf
+PAPERLESS_APPS="allauth.socialaccount.providers.github"
+PAPERLESS_SOCIALACCOUNT_PROVIDERS='{"github": {"APPS": [{"provider_id": "github","name": "Github","client_id": "<CLIENT_ID>","secret": "<CLIENT_SECRET>"}]}}'
+```
+
+Or, to use OpenID Connect ("OIDC"):
+
+```conf
+PAPERLESS_APPS="allauth.socialaccount.providers.openid_connect"
+PAPERLESS_SOCIALACCOUNT_PROVIDERS='
+{"openid_connect": {"APPS": [{"provider_id": "keycloak","name": "Keycloak","client_id": "paperless","secret": "<CLIENT_SECRET>","settings": { "server_url": "https://<KEYCLOAK_SERVER>/realms/<REALM>/.well-known/openid-configuration"}}]}}'
+```

docs/configuration.md

@@ -535,6 +535,36 @@ This is for use with self-signed certificates against local IMAP servers.
     Settings this value has security implications for the security of your email.
     Understand what it does and be sure you need to before setting.
 
+#### [`PAPERLESS_SOCIALACCOUNT_PROVIDERS=<json>`](#PAPERLESS_SOCIALACCOUNT_PROVIDERS) {#PAPERLESS_SOCIALACCOUNT_PROVIDERS}
+
+: This variable is used to setup login and signup via social account providers which are compatible with django-allauth.
+See the corresponding [django-allauth documentation](https://docs.allauth.org/en/0.60.0/socialaccount/providers/index.html)
+for a list of provider configurations. You will also likely need to include the relevant Django 'application' inside the
+[PAPERLESS_APPS](#PAPERLESS_APPS) setting.
+
+    Defaults to None, which does not enable any third party authentication systems.
+
+#### [`PAPERLESS_SOCIAL_AUTO_SIGNUP=<bool>`](#PAPERLESS_SOCIAL_AUTO_SIGNUP) {#PAPERLESS_SOCIAL_AUTO_SIGNUP}
+
+: Attempt to signup the user using retrieved email, username etc from the third party authentication
+system. See the corresponding
+[django-allauth documentation](https://docs.allauth.org/en/0.60.0/socialaccount/configuration.html)
+
+    Defaults to 'https'
+
+#### [`PAPERLESS_ACCOUNT_ALLOW_SIGNUPS=<bool>`](#PAPERLESS_ACCOUNT_ALLOW_SIGNUPS) {#PAPERLESS_ACCOUNT_ALLOW_SIGNUPS}
+
+: Allow users to signup for a new Paperless-ngx account using any setup third party authentication systems.
+
+    Defaults to 'https'
+
+#### [`PAPERLESS_ACCOUNT_DEFAULT_HTTP_PROTOCOL=<string>`](#PAPERLESS_ACCOUNT_DEFAULT_HTTP_PROTOCOL) {#PAPERLESS_ACCOUNT_DEFAULT_HTTP_PROTOCOL}
+
+: The protocol used when generating URLs, e.g. login callback URLs. See the corresponding
+[django-allauth documentation](https://docs.allauth.org/en/latest/account/configuration.html)
+
+    Defaults to 'https'
+
 ## OCR settings {#ocr}
 
 Paperless uses [OCRmyPDF](https://ocrmypdf.readthedocs.io/en/latest/)
@@ -905,6 +935,14 @@ documents.
 
     Default is none, which disables the temporary directory.
 
+#### [`PAPERLESS_APPS=<string>`](#PAPERLESS_APPS) {#PAPERLESS_APPS}
+
+: A comma-separated list of Django apps to be included in Django's
+[`INSTALLED_APPS`](https://docs.djangoproject.com/en/5.0/ref/applications/). This setting should
+be used with caution!
+
+    Defaults to None, which does not add any additional apps.
+
 ## Document Consumption {#consume_config}
 
 #### [`PAPERLESS_CONSUMER_DELETE_DUPLICATES=<bool>`](#PAPERLESS_CONSUMER_DELETE_DUPLICATES) {#PAPERLESS_CONSUMER_DELETE_DUPLICATES}