docs: add Readd example config for Seafile

Readds both the previous example for Seafile and an alternative setup with Authelia as an intermediary.

README.md

@@ -205,6 +205,7 @@ folder for help with:
   - [KeyCloak](example_configs/keycloak.md)
   - [Matrix](example_configs/matrix_synapse.yml)
   - [Organizr](example_configs/Organizr.md)
+  - [Seafile](example_configs/seafile.md)
 
 ## Comparisons with other services
 

example_configs/seafile.md

@@ -0,0 +1,89 @@
+# Configuration for Seafile
+Seafile's LDAP interface requires a unique, immutable user identifier in the format of `username@domain`. Since LLDAP does not provide an attribute like `userPrincipalName`, the only attribute that somewhat qualifies is therefore `mail`. However, using `mail` as the user identifier results in the issue that Seafile will treat you as an entirely new user if you change your email address through LLDAP. If this is not an issue for you, you can configure LLDAP as an authentication source in Seafile directly. A better but more elaborate way to use Seafile with LLDAP is by using Authelia as an intermediary. This document will guide you through both setups.
+
+## Configuring Seafile to use LLDAP directly
+Add the following to your `seafile/conf/ccnet.conf` file:
+```
+[LDAP]
+HOST = ldap://192.168.1.100:3890
+BASE = ou=people,dc=example,dc=com
+USER_DN = uid=admin,ou=people,dc=example,dc=com
+PASSWORD = CHANGE_ME
+LOGIN_ATTR = mail
+```
+* Replace `192.168.1.100:3890` with your LLDAP server's ip/hostname and port.
+* Replace every instance of `dc=example,dc=com` with your configured domain.
+
+After restarting the Seafile server, users should be able to log in with their email address and password.
+
+### Filtering by group membership
+If you only want members of a specific group to be able to log in, add the following line:
+```
+FILTER = memberOf=cn=seafile_user,ou=groups,dc=example,dc=com
+```
+* Replace `seafile_user` with the name of your group.
+
+## Configuring Seafile to use LLDAP with Authelia as an intermediary
+Authelia is an open-source authentication and authorization server that can use LLDAP as a backend and act as an OpenID Connect Provider. We're going to assume that you have already set up Authelia and configured it with LLDAP.
+If not, you can find an example configuration [here](authelia_config.yml).
+
+1. Add the following to Authelia's `configuration.yml`:
+```
+identity_providers:
+  oidc:
+    hmac_secret: Your_HMAC_Secret #Replace with a random string
+    issuer_private_key: |
+        -----BEGIN RSA PRIVATE KEY-----
+        Your_Private_Key
+        #See https://www.authelia.com/configuration/identity-providers/open-id-connect/#issuer_private_key for instructions on how to generate a key
+        -----END RSA PRIVATE KEY-----
+    cors:
+      endpoints:
+        - authorization
+        - token
+        - revocation
+        - introspection
+        - userinfo
+    clients:
+      - id: seafile
+        description: Seafile #The display name of the application. Will show up on Authelia consent screens
+        secret: Your_Shared_Secret #Replace with random string
+        public: false
+        authorization_policy: one_factor #Can also be two_factor
+        scopes:
+          - openid
+          - profile
+          - email
+        redirect_uris:
+          - https://seafile.example.com/oauth/callback/
+        userinfo_signing_algorithm: none
+        pre_configured_consent_duration: 6M
+        #On first login you must consent to sharing information between Authelia and Seafile. This option configures the amount of time after which you need to reconsent.
+        # y = years, M = months, w = weeks, d = days
+```
+
+2. Add the following to `seafile/conf/seahub_settings.py`
+```
+ENABLE_OAUTH = True
+OAUTH_ENABLE_INSECURE_TRANSPORT = True
+OAUTH_CLIENT_ID = 'seafile' #Must be the same as in Authelia
+OAUTH_CLIENT_SECRET = 'Your_Shared_Secret' #Must be the same as in Authelia
+OAUTH_REDIRECT_URL = 'https://seafile.example.com/oauth/callback/'
+OAUTH_PROVIDER_DOMAIN = 'auth.example.com'
+OAUTH_AUTHORIZATION_URL = 'https://auth.example.com/api/oidc/authorization'
+OAUTH_TOKEN_URL = 'https://auth.example.com/api/oidc/token'
+OAUTH_USER_INFO_URL = 'https://auth.example.com/api/oidc/userinfo'
+OAUTH_SCOPE = [
+  "openid",
+  "profile",
+  "email",
+]
+OAUTH_ATTRIBUTE_MAP = {
+    "preferred_username": (True, "email"), #Seafile will create a unique identifier of your <LLDAP's User ID >@<the value specified in OAUTH_PROVIDER_DOMAIN>. The identifier is not visible to the user and not actually used as the email address unlike the value suggests
+    "name": (False, "name"),
+    "id": (False, "not used"),
+    "email": (False, "contact_email"),
+}
+```
+
+Restart both your Authelia and Seafile server. You should see a "Single Sign-On" button on Seafile's login page. Clicking it should redirect you to Authelia. If you use the [example config for Authelia](authelia_config.yml), you should be able to log in using your LLDAP User ID.