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docs/ops/RAP_HOST_AGENT_MONITOR.md

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+# RAP host-agent monitor
+
+`rap-host-agent monitor-loop` is the local watchdog that runs near a node host.
+It complements the update loop:
+
+- starts watched Docker containers when they are stopped;
+- restarts watched containers when Docker health is `unhealthy`;
+- restarts containers stuck in `restarting` longer than the stale threshold;
+- rate-limits repeated remediation with a restart cooldown;
+- watches disk pressure and runs safe cleanup when the cleanup threshold is reached;
+- removes old `/tmp/rap-*` and `/tmp/go-build*` build directories;
+- writes an optional JSON status file;
+- reports monitor status to the control plane through the node update-status channel.
+
+Example:
+
+```bash
+rap-host-agent monitor-loop \
+  --backend-url http://127.0.0.1:18121/api/v1 \
+  --cluster-id cfc0743d-d960-49fb-9de8-96e063d5e4aa \
+  --node-id 108a0d66-d65e-4dea-b9a8-135366bf7dba \
+  --current-version 0.2.261-vpnfarm \
+  --interval-seconds 60 \
+  --disk-warn-percent 80 \
+  --disk-cleanup-percent 85 \
+  --disk-critical-percent 95 \
+  --status-file /tmp/rap-web-admin/html/downloads/ops/host-monitor-status.json \
+  --watch-container rap_test_postgres \
+  --watch-container rap_test_redis \
+  --watch-container rap_test_backend
+```
+
+On the shared test Docker host the current public status file is:
+
+`http://docker-test.cin.su:18080/downloads/ops/host-monitor-status.json`