docker: Fix permission issues, remove user from container

docker-entrypoint.sh

@@ -15,4 +15,24 @@ for SECRET in LLDAP_JWT_SECRET LLDAP_LDAP_USER_PASS; do
     fi
 done
 
+CONFIG_FILE=/data/lldap_config.toml
+
+if [[ ( ! -w "/data" ) ]] || [[ ( ! -d "/data" ) ]]; then
+  echo "[entrypoint] The /data folder doesn't exist or cannot be written to. Make sure to mount
+  a volume or folder to /data to persist data across restarts, and that the current user can
+  write to it."
+  exit 1
+fi
+
+if [[ ! -f "$CONFIG_FILE" ]]; then
+  echo "[entrypoint] Copying the default config to $CONFIG_FILE"
+  echo "[entrypoint] Edit this file to configure LLDAP."
+  cp /app/lldap_config.docker_template.toml $CONFIG_FILE
+fi
+
+if [[ ! -r "$CONFIG_FILE" ]]; then
+  echo "[entrypoint] Config file is not readable. Check the permissions"
+  exit 1;
+fi
+
 exec /app/lldap "$@"