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/README.md

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+# restic
+
+Backup maintenance stack.
+
+Takes care of regularly pruning the backup repository and checking its integrity.
+Currently only supports S3 as a backend.
+
+## Defaults
+
+```yaml
+restic_timezone: US/Chicago
+```
+
+The timezone to be used for the cronjob.
+
+```yaml
+restic_version: latest
+```
+
+The docker image version to be used in stack creation.
+
+```yaml
+restic_repo: s3.eu-central-1.wasabisys.com/myrepo
+restic_pass: <restic-pass>
+```
+
+The repository url and the restic repository password.
+See the restic documentation for more information.
+
+```yaml
+restic_s3_key: <s3-key>
+restic_s3_secret: <s3-secret>
+```
+
+The restic S3 credentials, i.e. the `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY`.
+
+```yaml
+restic_prune_cron: 0 0 4 * * *
+restic_forget_args: --prune --keep-last 14 --keep-daily 2 --keep-weekly 2
+```
+
+The default prune and forget cronjob schedule and arguments: Prune the repository every day at 4:00 AM and keep the last 14 snapshots, 2 daily snapshots and 2 weekly snapshots.
+
+```yaml
+restic_check_cron: 0 15 5 * * *
+restic_check_args: --read-data-subset=5%
+```
+
+The default check cronjob schedule and arguments: Check the repository integrity every day at 5:15 AM and in addition to structural checks, read 5 randomly chosen % for a data integrity check.

roles/restic/defaults/main.yml

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+---
+# 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>

roles/restic/meta/main.yml

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+---
+galaxy_info:
+  author: Marty Oehme
+  description: Installs a restic-based backup maintenance stack.
+  license: GPL-3.0-only
+  min_ansible_version: "2.9"
+  galaxy_tags: []

roles/restic/tasks/main.yml

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+---
+- name: Create local backup directory
+  ansible.builtin.file:
+    state: directory
+    path: "{{ restic_repo }}"
+    owner: root
+    group: root
+    mode: 0770
+  when: restic_repo is regex('^/.+')
+
+- name: Deploy restic to compose
+  community.docker.docker_compose_v2:
+    project_name: restic
+    definition: "{{ lookup('template', 'docker-compose.yaml.j2') | from_yaml }}"
+    remove_orphans: true
+    wait: true
+    wait_timeout: 60

roles/restic/templates/docker-compose.yaml.j2

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+services:
+  prune:
+    image: "mazzolino/restic:{{ restic_version }}"
+    hostname: docker
+    environment:
+      - "TZ={{ restic_tz }}"
+      - "SKIP_INIT={{ not restic_auto_init }}"
+      - "RUN_ON_STARTUP=true"
+      - "PRUNE_CRON={{ restic_prune_cron }}"
+      - "RESTIC_FORGET_ARGS={{ restic_forget_args }}"
+      - "RESTIC_REPOSITORY={{ restic_repo }}"
+      - "RESTIC_PASSWORD={{ restic_pass }}"
+      - "AWS_ACCESS_KEY_ID={{ restic_s3_key }}"
+      - "AWS_SECRET_ACCESS_KEY={{ restic_s3_secret }}"
+{% if restic_repo is regex('^/.+') %}
+    volumes:
+      - "{{ restic_repo }}:{{ restic_repo }}"
+{% endif %}
+
+  check:
+    image: "mazzolino/restic:{{ restic_version }}"
+    hostname: docker
+    environment:
+      - "TZ={{ restic_tz }}"
+      - "SKIP_INIT=true" # only run init on one container to avoid race cond
+      - "RUN_ON_STARTUP=false"
+      - "CHECK_CRON={{ restic_check_cron }}"
+      - "RESTIC_CHECK_ARGS={{ restic_check_args }}"
+      - "RESTIC_REPOSITORY={{ restic_repo }}"
+      - "RESTIC_PASSWORD={{ restic_pass }}"
+      - "AWS_ACCESS_KEY_ID={{ restic_s3_key }}"
+      - "AWS_SECRET_ACCESS_KEY={{ restic_s3_secret }}"
+{% if restic_repo is regex('^/.+') %}
+    volumes:
+      - "{{ restic_repo }}:{{ restic_repo }}"
+{% endif %}

roles/restic/vars/main.yml

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+---
+stack_name: restic
+
+stack_image: "mazzolino/restic"
+
+stack_compose: "{{ lookup('template', 'docker-stack.yml.j2') | from_yaml }}"
+
+backup_enable: true