feat: add host_agent plugin — push-model host resource monitoring

Lightweight stdlib-only Python agent runs on each monitored host,
collects CPU / memory / disk / load / uptime from /proc every 30s,
and POSTs signed payloads to the Roundtable ingest endpoint. One-line
curl-pipe installer creates a hardened systemd unit; admin UI manages
host registrations with rotate / revoke.

- agent.py: 370 LoC single-file daemon, ring buffer + exponential backoff
- ingest route: bearer-token auth, metric expansion into plugin_metrics
- install.sh.j2: systemd unit with NoNewPrivileges / ProtectSystem / ProtectHome
- settings UI: add host / rotate token / delete registration (admin-only)
- dashboard widgets: fleet-glance table + per-host history chart
- stale-agent scheduler: 60s log warning for agents past 180s silence

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
2026-04-15 01:04:51 -04:00
parent be4654fc72
commit 7468806bad
14 changed files with 1210 additions and 0 deletions
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#!/bin/sh
# Roundtable host agent installer
# Generated for: {{ host_name }} ({{ host_address }})
# Roundtable URL: {{ url }}
set -e
ROUNDTABLE_URL="{{ url }}"
AGENT_TOKEN="{{ token }}"
AGENT_VERSION="{{ agent_version }}"
AGENT_USER="roundtable-agent"
AGENT_DIR="/usr/local/lib/roundtable-agent"
CONF_FILE="/etc/roundtable-agent.conf"
UNIT_FILE="/etc/systemd/system/roundtable-agent.service"
# ── preflight ────────────────────────────────────────────────────────────────
[ "$(id -u)" = "0" ] || { echo "must run as root (use sudo)"; exit 1; }
command -v systemctl >/dev/null 2>&1 || { echo "systemd not found — unsupported init system"; exit 1; }
command -v python3 >/dev/null 2>&1 || { echo "python3 not found — install python3 first"; exit 1; }
# Handle --uninstall
if [ "${1:-}" = "--uninstall" ]; then
systemctl disable --now roundtable-agent.service 2>/dev/null || true
rm -f "$UNIT_FILE" "$CONF_FILE"
rm -rf "$AGENT_DIR"
systemctl daemon-reload
# keep the system user — removing it risks orphaned files elsewhere
echo "uninstalled"
exit 0
fi
# ── create system user ───────────────────────────────────────────────────────
if ! id "$AGENT_USER" >/dev/null 2>&1; then
useradd --system --no-create-home --shell /usr/sbin/nologin "$AGENT_USER"
fi
# ── drop the agent file ──────────────────────────────────────────────────────
mkdir -p "$AGENT_DIR"
curl -sSL "${ROUNDTABLE_URL}/plugins/host_agent/agent.py" -o "$AGENT_DIR/agent.py"
chmod 0755 "$AGENT_DIR/agent.py"
chown root:root "$AGENT_DIR/agent.py"
# ── write config ─────────────────────────────────────────────────────────────
cat > "$CONF_FILE" <<EOF
url = $ROUNDTABLE_URL
token = $AGENT_TOKEN
interval_seconds = 30
EOF
chown "root:$AGENT_USER" "$CONF_FILE"
chmod 0640 "$CONF_FILE"
# ── write systemd unit ───────────────────────────────────────────────────────
cat > "$UNIT_FILE" <<EOF
[Unit]
Description=Roundtable host agent
After=network-online.target
Wants=network-online.target
[Service]
Type=simple
User=$AGENT_USER
ExecStart=/usr/bin/python3 $AGENT_DIR/agent.py
Restart=on-failure
RestartSec=10
NoNewPrivileges=yes
ProtectSystem=strict
ProtectHome=yes
PrivateTmp=yes
ReadOnlyPaths=/proc /sys
[Install]
WantedBy=multi-user.target
EOF
systemctl daemon-reload
systemctl enable --now roundtable-agent.service
echo
echo "Roundtable host agent $AGENT_VERSION installed and running."
echo "Check status: systemctl status roundtable-agent"
echo "Logs: journalctl -u roundtable-agent -f"
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{% extends "base.html" %}
{% block title %}Host Agent — Roundtable{% endblock %}
{% block content %}
<h1 class="page-title">Host Agent — Registered Hosts</h1>
{% if new_token %}
<div class="card" style="background:var(--accent-bg);">
<h3>New token — copy this install command now</h3>
<p style="font-size:0.82rem;color:var(--text-muted);">
This is the only time the raw token is shown. Rotate if you lose it.
</p>
<pre style="user-select:all;word-break:break-all;">curl -sSL '{{ install_url }}' | sudo sh</pre>
</div>
{% endif %}
<div class="card">
<form method="post" action="/plugins/host_agent/settings/add-host"
style="display:flex;gap:0.5rem;align-items:flex-end;">
<div class="form-group">
<label>Host name</label>
<input type="text" name="name" required>
</div>
<div class="form-group">
<label>Address (optional)</label>
<input type="text" name="address">
</div>
<button type="submit" class="btn">Add host</button>
</form>
</div>
<div class="card">
<table>
<thead>
<tr>
<th>Host</th><th>Agent version</th><th>Distro</th>
<th>Last seen</th><th>Actions</th>
</tr>
</thead>
<tbody>
{% for item in registrations %}
<tr>
<td>{{ item.host.name if item.host else item.reg.host_id }}</td>
<td>{{ item.reg.agent_version or "—" }}</td>
<td>{{ item.reg.distro or "—" }}</td>
<td>{{ item.reg.last_seen_at.strftime("%Y-%m-%d %H:%M:%S") if item.reg.last_seen_at else "never" }}</td>
<td>
<form method="post" action="/plugins/host_agent/settings/{{ item.reg.host_id }}/rotate-token" style="display:inline;">
<button type="submit" class="btn btn-ghost">Rotate token</button>
</form>
<form method="post" action="/plugins/host_agent/settings/{{ item.reg.host_id }}/delete" style="display:inline;">
<button type="submit" class="btn btn-ghost">Delete</button>
</form>
</td>
</tr>
{% else %}
<tr><td colspan="5">No hosts registered. Add one above.</td></tr>
{% endfor %}
</tbody>
</table>
</div>
{% endblock %}
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<div class="widget-history">
<h3>{{ host.name }} — last {{ hours }}h</h3>
<canvas id="host-agent-chart-{{ host.id }}" width="600" height="200"></canvas>
<script>
(function() {
const ctx = document.getElementById("host-agent-chart-{{ host.id }}").getContext("2d");
const series = {{ series|tojson }};
new Chart(ctx, {
type: "line",
data: {
datasets: [
{ label: "CPU %", data: series.cpu_pct.map(p => ({x: p.t, y: p.v})) },
{ label: "Mem %", data: series.mem_used_pct.map(p => ({x: p.t, y: p.v})) },
{ label: "Disk % worst", data: series.disk_used_pct_worst.map(p => ({x: p.t, y: p.v})) },
],
},
options: {
responsive: true,
scales: { x: { type: "time" }, y: { min: 0, max: 100 } },
},
});
})();
</script>
</div>
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<table class="widget-table">
<thead>
<tr><th>Host</th><th>CPU %</th><th>Mem %</th><th>Disk % (worst)</th><th>Load 1m</th><th>Last seen</th></tr>
</thead>
<tbody>
{% for r in rows %}
<tr>
<td><a href="/plugins/host_agent/{{ r.host.id }}/">{{ r.host.name }}</a></td>
<td>{{ "%.1f"|format(r.cpu_pct) if r.cpu_pct is not none else "—" }}</td>
<td>{{ "%.1f"|format(r.mem_used_pct) if r.mem_used_pct is not none else "—" }}</td>
<td>{{ "%.1f"|format(r.disk_worst) if r.disk_worst is not none else "—" }}</td>
<td>{{ "%.2f"|format(r.load_1m) if r.load_1m is not none else "—" }}</td>
<td>{{ r.reg.last_seen_at.strftime("%H:%M:%S") if r.reg.last_seen_at else "never" }}</td>
</tr>
{% else %}
<tr><td colspan="6">No hosts with agent data yet.</td></tr>
{% endfor %}
</tbody>
</table>