Add a systemd unit file + default with flags

README.md

@@ -47,6 +47,35 @@ scrape_configs:
       - targets: ['localhost:9781']
 ```
 
+## systemd
+
+A unit file and defaults file are included.
+
+```sh
+# install binary
+go build -o /usr/local/bin/ctlog-uptime-exporter .
+
+# install defaults (edit to taste)
+cp ctlog-uptime-exporter.default /etc/default/ctlog-uptime-exporter
+
+# install and start the service
+cp ctlog-uptime-exporter.service /etc/systemd/system/
+systemctl daemon-reload
+systemctl enable --now ctlog-uptime-exporter
+```
+
+Runtime flags are controlled via the `ARGS` variable in `/etc/default/ctlog-uptime-exporter`.
+
+## Grafana dashboard
+
+`dashboard.json` can be imported directly into Grafana (Dashboards -> Import).
+It expects a Prometheus datasource and provides:
+
+- Summary stats: number of logs, endpoint types, average uptime, degraded count, fetch status, last fetch time
+- Variable selectors for Log URL and Endpoint (both multi-select with All)
+- Time series panel showing the rolling 24h uptime ratio over the chosen time range
+- Table of the top N least-available log/endpoint pairs (N is selectable: 5, 10, 25, 50)
+
 ## License
 
 Apache 2.0 - see [LICENSE](LICENSE).