Do not redefine matrix-postgres role vars in matrix-postgres-backup

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/868

group_vars/matrix_servers

@@ -1786,6 +1786,8 @@ matrix_postgres_backup_connection_port: "{{ matrix_postgres_connection_port }}"
 matrix_postgres_backup_connection_username: "{{ matrix_postgres_connection_username }}"
 matrix_postgres_backup_connection_password: "{{ matrix_postgres_connection_password }}"
 
+matrix_postgres_backup_postgres_data_path: "{{ matrix_postgres_data_path if matrix_postgres_enabled else '' }}"
+
 # the default matrix synapse databse is not always part of the matrix_postgres_additional_databases variable thus we have to add it if the default database is used
 matrix_postgres_backup_databases: |
   {{

roles/matrix-postgres-backup/defaults/main.yml

@@ -14,8 +14,10 @@ matrix_postgres_backup_healthcheck_port: "8080"
 matrix_postgres_backup_databases: []
 matrix_postgres_backup_path: "{{ matrix_base_data_path }}/postgres-backup"
 
-matrix_postgres_base_path: "{{ matrix_base_data_path }}/postgres"
-matrix_postgres_data_path: "{{ matrix_postgres_base_path }}/data"
+# Specifies where the Postgres data is.
+# We use this to autodetect the Postgres version during playbook runtime (by parsing the `PG_VERSION` file contained there).
+# You can leave this empty to prevent auto-detection.
+matrix_postgres_backup_postgres_data_path: ""
 
 matrix_postgres_backup_architecture: amd64
 

roles/matrix-postgres-backup/tasks/setup_postgres_backup.yml

@@ -4,14 +4,14 @@
 # Tasks related to setting up an internal postgres server
 #
 - import_tasks: "{{ role_path }}/tasks/util/detect_existing_postgres_version.yml"
-  when: matrix_postgres_enabled|bool
+  when: 'matrix_postgres_backup_enabled|bool and matrix_postgres_backup_postgres_data_path != ""'
 
 # If we have found an existing version (installed from before), we use its corresponding Docker image.
 # If not, we install using the latest Postgres.
 #
 # Upgrading is supposed to be performed separately and explicitly (see `upgrade_postgres.yml`).
 - set_fact:
-    matrix_postgres_backup_docker_image_to_use: "{{ matrix_postgres_backup_docker_image_latest if matrix_postgres_backup_detected_version_corresponding_docker_image == '' else matrix_postgres_backup_detected_version_corresponding_docker_image }}"
+    matrix_postgres_backup_docker_image_to_use: "{{ matrix_postgres_backup_docker_image_latest if matrix_postgres_backup_detected_version_corresponding_docker_image|default('') == '' else matrix_postgres_backup_detected_version_corresponding_docker_image }}"
   when: matrix_postgres_backup_enabled|bool
 
 - name: Ensure postgres backup Docker image is pulled