metricspi: Scrape Zincati metrics from CoreOS hosts

Zincati is the automatic update manager on Fedora CoreOS.  It exposes
Prometheus metrics for host/update statistics, which are useful to track
the progress of automatic updates and identify update issues.

Zinciti actually exposes its metrics via a Unix socket on the
filesystem.  Another process, [local_exporter], is required to expose
the metrics from this socket via HTTP so Prometheus can scrape them.

[local_exporter]: https://github.com/lucab/local_exporter

group_vars/metricspi/scrape.yml

@@ -234,3 +234,17 @@ vmagent_scrape_configs:
   static_configs:
   - targets:
     - kubernetes.pyrocufflink.blue:6443
+
+- job_name: zincati
+  scrape_interval: 1m
+  metrics_path: /bridge?selector=zincati
+  static_configs:
+  - targets:
+    - k8s-aarch64-n0.pyrocufflink.blue
+    - nvr1.pyrocufflink.blue
+  relabel_configs:
+  - source_labels: [__address__]
+    target_label: instance
+  - source_labels: [__address__]
+    target_label: __address__
+    replacement: '$1:9598'