Merge pull request #641 from haiwen/thunmnail-server

Add explanation of how to configure thunmnail-server at a cluster

Author: freeplant

manual/extension/thumbnail-server.md

@@ -55,7 +55,7 @@ Then modify the `.env` file according to your environment. The following fields
 | `SEAFILE_MYSQL_DB_PASSWORD`| Seafile MySQL password                                                                                    |  
 | `TIME_ZONE`            | Time zone                                                                                                     |  
 | `JWT_PRIVATE_KEY`      | JWT key, the same as the config in Seafile `.env` file                                                         |  
-| `INNER_SEAHUB_SERVICE_URL`| Intranet URL for accessing Seahub component, like `http://<your Seafile server intranet IP>`.  |   
+| `INNER_SEAHUB_SERVICE_URL`| Intranet URL for accessing Seahub component, like `http://<your Seahub component intranet IP>`.  |   
 | `SEAF_SERVER_STORAGE_TYPE`   | What kind of the Seafile data for storage. Available options are `disk` (i.e., local disk), `s3` and `multiple` (see the details of [multiple storage backends](../setup/setup_with_multiple_storage_backends.md)) |
 | `S3_COMMIT_BUCKET`   | S3 storage backend commit objects bucket |
 | `S3_FS_BUCKET`   | S3 storage backend fs objects bucket |
@@ -70,7 +70,17 @@ Then modify the `.env` file according to your environment. The following fields
 | `S3_SSE_C_KEY`   | A string of 32 characters can be generated by openssl rand -base64 24. It can be any 32-character long random string. It's required to use V4 authentication protocol and https if you enable SSE-C. |
 | `NON_ROOT`   | Run container without a root user      | `false` |
 
-Then you can run thumbnail server with the following command:
+
+!!! tip "About INNER_SEAHUB_SERVICE_URL"
+    The thumbnail server must call the Seahub component to verify permissions.
+    
+    The INNER_SEAHUB_SERVICE_URL should point to the Seahub URL located at one of the front-end nodes, such as http://192.168.0.10 .
+
+    Alternatively, you can use an external URL for the thumbnail server to access Seahub, like https://seafile.example.com . In this scenario, it is essential to ensure that the CA is trusted on the thumbnail server node.
+
+
+
+You can run thumbnail server with the following command:
 
 ```sh
 docker compose up -d