Switch Prometheus/collectd to pull

Transitioning from push-based to pull-based monitoring with
Prometheus/collectd.  The *write_prometheus* plugin will be installed on
all hosts, and Prometheus will be configured to scrape them directly.

collectd.yml

@@ -4,7 +4,7 @@
     tags:
     - collectd
 
-- hosts: prometheus
+- hosts: collectd-prometheus
   roles:
   - role: collectd-prometheus
     tags:

group_vars/collectd.yml

@@ -0,0 +1 @@
+collectd_prometheus_allow_outside: true

group_vars/prometheus.yml

@@ -1,5 +0,0 @@
-collectd_network_servers: []
-collectd_network_listen:
-- '::'
-- ff18::efc0:4a42
-collectd_prometheus_host: '::1'

host_vars/vmhost0.pyrocufflink.blue.yml

@@ -45,6 +45,3 @@ networkd_networks:
 
 samba_interfaces:
 - enp5s0
-collectd_network_servers:
-- host: ff18::efc0:4a42
-  interface: enp5s0

host_vars/vmhost1.pyrocufflink.blue.yml

@@ -10,6 +10,3 @@ dhcpcd_interfaces:
 storage_iface: bond1
 samba_interfaces:
 - enp5s0
-collectd_network_servers:
-- host: ff18::efc0:4a42
-  interface: enp5s0

hosts

@@ -20,6 +20,9 @@ burp1.pyrocufflink.blue
 [collectd:children]
 pyrocufflink
 
+[collectd-prometheus:children]
+collectd
+
 [dch-proxy]
 
 [dch-vpn]