Added documentation for S3 storage configuration

avatar-realm-resource/README.md

@@ -19,17 +19,32 @@ To build the JAR artifact it is sufficient to type
 
     mvn clean package
 
-### Installation and configuration
+### Installation
 
 The type of the storage to be used is configured in the `org.gcube.keycloak.avatar.storage.AvatarStorageProviderFactory` file under the `META-INF/services/` folder of the module source/JAR.
 
-To use the S3 persistence, the content of the file should be: `org.gcube.keycloak.avatar.storage.s3.MinioAvatarStorageProviderFactory`
+To use the S3 persistence (default), the content of the file should be: `org.gcube.keycloak.avatar.storage.s3.MinioAvatarStorageProviderFactory`
 
 #### Quarkus based Keycloak
 
 In order to deploy the module it is sufficient to copy into the `[keycloak-home]/providers` folder.
 
-##### 
+### Configuration
+
+In order to configure the storage provider you have to add some lines to the `[keycloak-home]/conf/keycloak.conf` configuration file.
+
+Let's see the specific setting for every provider.
+
+#### Minio avatar storage provider
+
+To configure the S3 endpoint, name and credentials you should use the following configuration lines:
+
+    spi-avatar-storage-avatar-storage-s3-server-url=[server-address]
+    spi-avatar-storage-avatar-storage-s3-access-key=[access-key]
+    spi-avatar-storage-avatar-storage-s3-secret-key=[secret-key]
+    spi-avatar-storage-avatar-storage-s3-root-bucket=[bucket-name]
+
+#### File avatar storage provider
 
 If you need to customize the folder where avatars images are saved (defaulting `[user-home]/avatar`) you can add the following line to the `[keycloak-home]/conf/keycloak.conf` file:
 
@@ -41,7 +56,6 @@ By default the `username` of the user is used as a filename for the image into t
 
     spi-avatar-storage-avatar-storage-file-use-email-as-filename=true
 
-
 ## Change log
 
 See [CHANGELOG.md](CHANGELOG.md).