chore(restic): allow adding commandline parameters to restic backup command

roles/restic/README.md

@@ -24,6 +24,14 @@ To control what and how data is backed up, see:
 - `restic_backup_commands`: takes an array of dictionaries of
   the form `{command, filename}`, where the output of `command`
   is fed into `restic backup --stdin --stdin-filename {{ filename }}`.
+- `restic_backup_parameters`: takes a dictionary of key-value pairs
+  which are added as commandline parameters to the `restic backup` call
+  for `restic_backup_paths`, for example:
+  ```yaml
+  restic_backup_parameters:
+    exclude: /home/user/.cache/
+    verbose:
+  ```
 
 To control when backups are run, see `restic_systemd_timer_on_calendar`
 and `restic_systemd_timer_accuray_sec`.

roles/restic/defaults/main.yml

@@ -9,6 +9,7 @@ restic_password: ~
 
 restic_backup_paths: []
 restic_backup_commands: []
+restic_backup_parameters: {}
 
 restic_systemd_user: root
 restic_systemd_unit_name: "restic"

roles/restic/templates/restic.service.j2

@@ -17,7 +17,21 @@ ExecStart=/bin/sh -c '{{ commands.command }} | {{ restic_binary }} backup --verb
 {% endfor %}
 
 {% if restic_backup_paths | length > 0 %}
-ExecStart={{ restic_binary }} --verbose backup {{ restic_backup_paths | join(' ') }}
+ExecStart={{ restic_binary }} backup {{ restic_backup_paths | join(' ') }}{% if restic_backup_parameters | length > 0 %} \
+    {% for param in restic_backup_parameters | dict2items %}
+      {%- set outer_loop = loop %}
+      {%- if param.value is not string and param.value is not mapping and param.value is iterable -%}
+        {%- for item in param.value -%}
+    --{{ param.key }}={{ item }}{% if not loop.last %} \
+    {% endif -%}
+        {%- endfor -%}
+      {%- else -%}
+    --{{ param.key }}{% if param.value %}={{ param.value }}{% endif %}
+      {%- endif %}
+      {%- if not outer_loop.last %} \{% endif %}
+
+    {% endfor -%}
+{% endif %}
 {% endif %}
 
 ExecStartPost=-{{ restic_binary }} snapshots