telegraf: Add parameter to enable ZFS stats

Previous templates used the assumptioon, that FreeBSD will always have
ZFS and nothing else.

README.md

@@ -70,6 +70,7 @@ Telegraf is configured with basic host telemetry by default. You can add more fe
 - `telegraf_docker_file`: filename of the docker telegraf config part in `{{role_path}}/templates` (default `telegraf-docker.conf`).
 - `telegraf_unifi_file`: filename of the SNMP telegraf config part in `{{role_path}}/templates` (default `telegraf-UniFi.conf.j2`).
 - `telegraf_airmax_file`: filename of the SNMP telegraf config part in `{{role_path}}/templates` (default `telegraf-AirMAX.conf.j2`).
+- `telegraf_enable_zfs`: gather ZFS stats (default `false`).
 
 Optional settings:
 - `telegraf_interval`: Data sampling interval (default `300s`)

defaults/main.yml

@@ -9,6 +9,7 @@ telegraf_interval: "300s"
 telegraf_docker_file: "telegraf-docker.conf"
 telegraf_unifi_file: "telegraf-UniFi.conf.j2"
 telegraf_airmax_file: "telegraf-AirMAX.conf.j2"
+telegraf_enable_zfs: false
 
 exim_etc_mailname: "{{ inventory_hostname }}"
 exim_skip_install: false

templates/telegraf.conf.j2

@@ -84,7 +84,7 @@
   name_override = "cpu_temp"
 {% endif %}
 
-{% if ((override_os_family is defined) | ternary(override_os_family,ansible_os_family)) == 'FreeBSD' %}
+{% if telegraf_enable_zfs %}
 # Read metrics of ZFS from arcstats, zfetchstats, vdev_cache_stats, and pools
 [[inputs.zfs]]
   ## By default, telegraf gather all zfs stats