restic: Add stack

Adapted from cloudserve-infrastructure, implements a backup stack using
restic. The actual backups have to be implemented by individual other
roles but this sets up initialization, pruning and checking of a repository.

roles/restic/defaults/main.yml

@@ -0,0 +1,24 @@
+---
+# inherited from global
+restic_enable: true
+restic_tz: "{{ timezone | default('America/Chicago') }}"
+
+restic_version: latest
+restic_auto_init: true
+
+restic_prune_cron: 0 0 4 * * * # go-cron starts with seconds in first pos
+restic_forget_args: --prune --keep-last 14 --keep-daily 2 --keep-weekly 2
+
+restic_check_cron: 0 30 4 * * SUN
+restic_check_args: --read-data-subset=15%
+
+restic_repo: /opt/stack_restic_backup
+restic_pass: my-restic-pass
+restic_s3_key:
+restic_s3_secret:
+
+# S3 example
+# restic_repo: s3.eu-central-1.wasabisys.com/myrepo
+# restic_pass: <restic-pass>
+# restic_s3_key: <s3-key>
+# restic_s3_secret: <s3-secret>