Add heartbeat from NetData to Alerta

tasks/heartbeat.yml

+---
+# file: roles/netdata/tasks/heartbeat.yml
+
+- name: "Crontab for heartbeat"
+  cron:
+    name: 'Heartbeat'
+    job: '/usr/bin/curl -XPOST {{ netdata_alerta_webhook }}/heartbeat -H ''Authorization: Key {{ netdata_alerta_apikey }}'' -H ''Content-type: application/json'' -d ''{"origin":"{{ inventory_hostname }}","timeout":120}'' >/dev/null 2>&1'
+  tags: 'cron'

tasks/main.yml

@@ -30,4 +30,6 @@
   - import_tasks: varnish.yml
     when: groups['varnishserver'] is defined and inventory_hostname in groups['varnishserver']
 
+  - import_tasks: heartbeat.yml
+
   when: '"netdata" not in excluded_roles'