Add collector role

Sets up prometheus to pull metrics, with telegraf to process SNMP data.

roles/collector/templates/prometheus-job.yml.j2

@@ -0,0 +1,20 @@
+{% set devices = query("netbox.netbox.nb_lookup", "devices", api_filter="{{ item.nb_filter }}", raw_data=true)
+    | selectattr("primary_ip")
+    | map(attribute="name")
+    | map("extract", hostvars) -%}
+
+scrape_configs:
+  - job_name: "{{ item.name }}"
+    relabel_configs:
+      - source_labels: [__address__]
+        regex: '([^.]+).*'
+        target_label: name
+        replacement: ${1}
+    static_configs:
+      - targets:
+{% for address in devices
+    | selectattr("dns_name", "defined")
+    | map(attribute="dns_name")
+    | reject("none") | sort | unique %}
+          - "{{ address }}:9100"
+{% endfor %}