Improve the docker experience

- Only one env variable to configure on first usage
- Auto-generate a default config
- Improve doc

src/docker/start.sh

@@ -1,2 +1,26 @@
 #!/bin/sh
+
+if ! [ -z "$CONF_FILE_PATH" ] && ! [ -f "CONF_FILE_PATH" ]; then
+    echo "Generating config file $CONF_FILE_PATH"
+    touch "CONF_FILE_PATH"
+
+    if ! [ -z "$MATRIX_DOMAIN" ]; then
+        echo "Setting matrix domain to $MATRIX_DOMAIN"
+        echo "matrix.domain: $MATRIX_DOMAIN" >> "$CONF_FILE_PATH"
+    fi
+
+    if ! [ -z "$SIGN_KEY_PATH" ]; then
+        echo "Setting signing key path to $SIGN_KEY_PATH"
+        echo "key.path: $SIGN_KEY_PATH" >> "$CONF_FILE_PATH"
+    fi
+
+    if ! [ -z "$SQLITE_DATABASE_PATH" ]; then
+        echo "Setting SQLite DB path to $SQLITE_DATABASE_PATH"
+        echo "storage.provider.sqlite.database: $SQLITE_DATABASE_PATH" >> "$CONF_FILE_PATH"
+    fi
+
+    echo "Starting mxisd..."
+    echo
+fi
+
 exec java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -Dspring.config.location=/etc/mxisd/ -Dspring.config.name=mxisd -jar /mxisd.jar