ansible: monitoring with Prometheus, Loki and Grafana

Nothing watched the servers: tonight's asxpio crash loop was found by
hand. On asxpio-ops, Prometheus (30 days), Loki (14 days) and Grafana
at gf.asxp.io (WireGuard only), with blackbox_exporter probing every
service from outside and postgres_exporter. On both hosts node_exporter
and cAdvisor on the VPC address, and Alloy shipping container logs, the
journal and Traefik's access log to Loki over the VPC.

Traefik and Forgejo expose their metrics; restic and the bucket replica
record their last success for node_exporter. Dashboards: an overview as
home, plus hosts, containers, Traefik, probes, Postgres and logs.
Alerts by email to me@asxp.io: host or service down, certificate under
14 days, disk or memory nearly full, a container restart-looping,
Postgres down, backup or replica stale.

Assisted-by: Claude:opus-5-5

ansible/roles/s3_replicate/templates/s3-replicate.j2

@@ -16,4 +16,8 @@ rclone sync hel1:{{ p.src }} fsn1:{{ p.dst }} \
 {% endfor %}
   --stats-one-line -v || failed=1
 {% endfor %}
+if [ $failed = 0 ]; then
+  f={{ monitoring_textfile_dir }}/s3_replicate.prom
+  printf '# HELP s3_replicate_last_success_timestamp_seconds Last fully successful hel1 to fsn1 replica.\n# TYPE s3_replicate_last_success_timestamp_seconds gauge\ns3_replicate_last_success_timestamp_seconds %s\n' "$(date +%s)" > "$f.tmp" && mv "$f.tmp" "$f"
+fi
 exit $failed