[deploy] Fixed password authentication failure #562

Prevents credential mismatch when reinstalling without clearing volumes.
The script now detects existing postgres_data volumes and aborts with
a clear warning instead of silently generating new credentials that
break database connectivity.

Fixes #562

Author: Srinath0916

deploy/auto-install.sh

@@ -103,6 +103,17 @@ setup_docker_openwisp() {
 	echo -ne ${GRN}"Do you have .env file? Enter filepath (leave blank for ad-hoc configuration): "${NON}
 	read env_path
 	if [[ ! -f "$env_path" ]]; then
+		if [[ ! -f "$INSTALL_PATH/.env" ]] && [[ ! -f "$ENV_BACKUP" ]]; then
+			if docker volume inspect "docker-openwisp_postgres_data" &>/dev/null; then
+				echo -e "${RED}CRITICAL: Existing database data detected!${NON}" | tee -a "$LOG_FILE"
+				echo -e "New credentials will break your connection to existing volumes."
+				echo -e "\nTo fix, either restore your .env or run:"
+				echo -e "${YLW}cd ${INSTALL_PATH} && docker compose down --volumes${NON}"
+				echo -e "or directly: ${YLW}docker volume rm docker-openwisp_postgres_data${NON}"
+				echo -e "\nAborting to prevent authentication failure." | tee -a "$LOG_FILE"
+				exit 1
+			fi
+		fi
 		# Dashboard Domain
 		echo -ne ${GRN}"(1/5) Enter dashboard domain: "${NON}
 		read dashboard_domain