v-m: Use dynamic discovery for some collectd nodes

We don't need to explicitly specify every single host individually.
Domain controllers, for example, are registered in DNS with SRV records.
Kubernetes nodes, of course, can be discovered using the Kubernetes API.
Both of these classes of nodes change frequently, so discovering them
dynamically is convenient.

victoria-metrics/scrape.yml

@@ -81,9 +81,6 @@ scrape_configs:
   static_configs:
   - targets:
     - gw1.pyrocufflink.blue
-    - k8s-aarch64-n0.pyrocufflink.blue
-    - k8s-aarch64-n1.pyrocufflink.blue
-    - k8s-amd64-n3.pyrocufflink.blue
     - loki0.pyrocufflink.blue
     - nut0.pyrocufflink.blue
     - nvr2.pyrocufflink.blue
@@ -94,12 +91,20 @@ scrape_configs:
   file_sd_configs:
   - files:
     - /scrape/collectd/scrape-collectd.yml
+  dns_sd_configs:
+  - names:
+    - _ldap._tcp.pyrocufflink.blue
+  kubernetes_sd_configs:
+  - role: node
   relabel_configs:
+  - action: labelmap
+    regex: __meta_kubernetes_node_label_(.+)
   - source_labels:
     - __address__
     target_label: host__tmp
   - source_labels: [__address__]
     target_label: __address__
+    regex: '([^:]+)(:.*)?'
     replacement: '$1:9103'
   metric_relabel_configs:
   - source_labels: