implement systemd timer for backing up the database

Signed-off-by: Jakub Sokołowski <jakub@status.im>

README.md

@@ -44,3 +44,29 @@ Configuration consists of two templates:
 
 * `grafana.ini.j2` - Grafana main configuration file.
 * `prometheus.yml.j2` - Initial configuration of the query backend(s).
+
+# Backups
+
+Done by a Sytemd timer daily:
+```
+ > sudo systemctl list-timers 'grafana-backup'
+NEXT                        LEFT          LAST PASSED UNIT                 ACTIVATES             
+Wed 2020-12-09 00:00:00 UTC 3h 10min left n/a  n/a    grafana-backup.timer grafana-backup.service
+
+ > sudo systemctl status grafana-backup
+● grafana-backup.service - Grafana batabase backup
+     Loaded: loaded (/lib/systemd/system/grafana-backup.service; static; vendor preset: enabled)
+     Active: inactive (dead) since Tue 2020-12-08 20:48:45 UTC; 6s ago
+TriggeredBy: ● grafana-backup.timer
+       Docs: https://github.com/status-im/infra-role-systemd-timer
+    Process: 1938613 ExecStart=/usr/local/bin/grafana-backup (code=exited, status=0/SUCCESS)
+   Main PID: 1938613 (code=exited, status=0/SUCCESS)
+```
+```
+ > ls -lh /var/backups/grafana
+total 2.3M
+-rw-r--r-- 1 root root 563K Dec  5 20:20 grafana-20201205-202043.db.gz
+-rw-r--r-- 1 root root 563K Dec  6 20:48 grafana-20201206-204838.db.gz
+-rw-r--r-- 1 root root 563K Dec  7 20:48 grafana-20201207-204840.db.gz
+-rw-r--r-- 1 root root 563K Dec  8 20:48 grafana-20201208-204845.db.gz
+```

defaults/main.yml

@@ -41,6 +41,13 @@ grafana_smtp_port: ~
 grafana_smtp_user: ~
 grafana_smtp_pass: ~
 
+# Backups
+grafana_backup_dir: '/var/backups/{{ grafana_service_name }}'
+grafana_backup_user: 'root'
+grafana_backup_frequency: 'daily'
+grafana_backup_timeout_sec: 30
+grafana_backup_max_kept: 14
+
 # optional anonymous access
 grafana_anonymous: false
 

tasks/backup.yml

@@ -0,0 +1,28 @@
+---
+- name: Create backups directory
+  file:
+    path: '{{ grafana_backup_dir }}'
+    owner: '{{ grafana_backup_user }}'
+    group: 'adm'
+    state: directory
+    mode: 0750
+
+- name: Create backup timer service
+  include_role: name=systemd-timer
+  vars:
+    systemd_timer_description: 'Grafana batabase backup'
+    systemd_timer_name: '{{ grafana_service_name }}-backup'
+    systemd_timer_user: '{{ grafana_backup_user }}'
+    systemd_timer_frequency: '{{ grafana_backup_frequency }}'
+    systemd_timer_timeout_sec: '{{ grafana_backup_timeout_sec }}'
+    systemd_timer_work_dir: '{{ grafana_backup_dir }}'
+    systemd_timer_start_on_creation: true
+    systemd_timer_script_content: |
+      #!/usr/bin/env bash
+      MAX_KEPT={{ grafana_backup_max_kept }}
+      DB_PATH="{{ grafana_cont_vol }}/lib/grafana.db"
+      TSAMP=$(date -u +%Y%m%d-%H%M%S)
+      echo "Saving Grafana database..."
+      gzip -c "${DB_PATH}" > "grafana-${TSAMP}.db.gz"
+      echo "Cleaning up old archives..."
+      rm -vf $(ls -Art | head -n -${MAX_KEPT})

tasks/main.yml

@@ -2,3 +2,4 @@
 - import_tasks: config.yml
 - import_tasks: container.yml
 - import_tasks: consul.yml
+- import_tasks: backup.yml