Add (Postgres + SQLite) support to matrix-mautrix-telegram bridge

I don't use this bridge, so this is completely untested.

roles/matrix-bridge-mautrix-telegram/defaults/main.yml

@@ -43,6 +43,35 @@ matrix_mautrix_telegram_systemd_wanted_services_list: []
 matrix_mautrix_telegram_appservice_token: ''
 matrix_mautrix_telegram_homeserver_token: ''
 
+
+# Database-related configuration fields.
+#
+# To use SQLite, stick to these defaults.
+#
+# To use Postgres:
+# - change the engine (`matrix_mautrix_telegram_database_engine: 'postgres'`)
+# - adjust your database credentials via the `matrix_mautrix_telegram_postgres_*` variables
+matrix_mautrix_telegram_database_engine: 'sqlite'
+
+matrix_mautrix_telegram_sqlite_database_path_local: "{{ matrix_mautrix_telegram_data_path }}/mautrix-telegram.db"
+matrix_mautrix_telegram_sqlite_database_path_in_container: "/data/mautrix-telegram.db"
+
+matrix_mautrix_telegram_postgres_username: 'matrix_mautrix_telegram'
+matrix_mautrix_telegram_postgres_password: 'some-password'
+matrix_mautrix_telegram_postgres_hostname: 'matrix-postgres'
+matrix_mautrix_telegram_postgres_port: 5432
+matrix_mautrix_telegram_postgres_db_name: 'matrix_mautrix_telegram'
+
+matrix_mautrix_telegram_postgres_connection_string: 'postgresql://{{ matrix_mautrix_telegram_postgres_username }}:{{ matrix_mautrix_telegram_postgres_password }}@{{ matrix_mautrix_telegram_postgres_hostname }}:{{ matrix_mautrix_telegram_postgres_port }}/{{ matrix_mautrix_telegram_postgres_db_name }}'
+
+matrix_mautrix_telegram_appservice_database: "{{
+	{
+		'sqlite': matrix_mautrix_telegram_sqlite_database_path_in_container,
+		'postgres': matrix_mautrix_telegram_postgres_connection_string,
+	}[matrix_mautrix_telegram_database_engine]
+}}"
+
+
 # Can be set to enable automatic double-puppeting via Shared Secret Auth (https://github.com/devture/matrix-synapse-shared-secret-auth).
 matrix_mautrix_telegram_login_shared_secret: ''
 

roles/matrix-bridge-mautrix-telegram/tasks/setup_install.yml

@@ -8,6 +8,26 @@
       The matrix-bridge-mautrix-telegram role needs to execute before the matrix-synapse role.
   when: "matrix_synapse_role_executed|default(False)"
 
+- block:
+  - name: Check if an SQLite database already exists
+    stat:
+      path: "{{ matrix_mautrix_telegram_sqlite_database_path_local }}"
+    register: matrix_mautrix_telegram_sqlite_database_path_local_stat_result
+
+  - name: Fail if an SQLite database already exists when using Postgres
+    fail:
+      msg: >-
+        matrix_mautrix_telegram_database_engine has been set to `postgres` (which is our new default now).
+        However, we've discovered an existing SQLite database in {{ matrix_mautrix_telegram_sqlite_database_path_local }}.
+        It appears that you've been using this bridge with the SQLite engine until now.
+        To continue using SQLite, opt into it explicitly: add `matrix_mautrix_telegram_database_engine: sqlite` to your vars.yml file and re-run this same command.
+        Alternatively, to migrate your existing SQLite database to Postgres:
+        1. Stop all services (`ansible-playbook -i inventory/hosts setup.yml --tags=stop`)
+        2. Import the SQLite database into Postgres (`ansible-playbook -v -i inventory/hosts setup.yml --tags=import-generic-sqlite-db --extra-vars='sqlite_database_path={{ matrix_mautrix_telegram_sqlite_database_path_local }} postgres_connection_string_variable_name=matrix_mautrix_telegram_postgres_connection_string'`)
+        3. Re-run the playbook (`ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,start`)
+    when: "matrix_mautrix_telegram_sqlite_database_path_local_stat_result.stat.exists"
+  when: "matrix_mautrix_telegram_database_engine == 'postgres'"
+
 - name: Ensure Mautrix Telegram image is pulled
   docker_image:
     name: "{{ matrix_mautrix_telegram_docker_image }}"

roles/matrix-bridge-mautrix-telegram/templates/config.yaml.j2

@@ -27,7 +27,7 @@ appservice:
     # Format examples:
     #   SQLite:   sqlite:///filename.db
     #   Postgres: postgres://username:password@hostname/dbname
-    database: postgres://mautrix_bridge_telegram:{{ matrix_addtional_databases | selectattr('name', 'equalto', 'matrix_bridge_telegram') | map(attribute='pass') | first }}@{{ matrix_postgres_connection_hostname }}/mautrix_bridge_telegram
+    database: {{ matrix_mautrix_telegram_appservice_database|to_json }}
 
     # Public part of web server for out-of-Matrix interaction with the bridge.
     # Used for things like login if the user wants to make sure the 2FA password isn't stored in