monitoring: nice labels for openwrt switches

* keep instance label
* add site and location labels

templates/prometheus.yml

@@ -38,9 +38,16 @@ scrape_configs:
 
   - job_name: 'snmp'
     static_configs:
-      - targets:
 {% for host in groups['switches_stock'] %}
-          - {{ hostvars[host]['ip'] }}
+      - targets: ["{{ hostvars[host]['ip'] }}"]
+        labels:
+          instance: "{{ host }}"
+{% if hostvars[host]['site'] is defined %}
+          site: "{{ hostvars[host]['site'] }}"
+{% endif %}
+{% if hostvars[host]['location'] is defined %}
+          location: "{{ hostvars[host]['location'] }}"
+{% endif %}
 {% endfor %}
     metrics_path: /snmp
     params: