Monitoring Dashdot with Vigilmon: Web UI Availability, Health Check, SSL Certificates & Response Time Alerts

Dashdot is the sleek, real-time system dashboard that gives you a live view of CPU usage, RAM, disk I/O, and network throughput for your self-hosted server. It's the glass you look through when a service slows down — the first place you check when latency spikes or a host runs hot. When Dashdot itself goes down, you lose that visibility exactly when you need it most. Vigilmon gives you external monitoring for Dashdot's web interface, health endpoint, and SSL certificate so you're alerted before your dashboard becomes unavailable during an incident.

What You'll Build

• An HTTP monitor for Dashdot web UI availability
• A health check monitor on the Dashdot API endpoint
• Response time tracking to detect performance degradation
• SSL certificate monitoring for your Dashdot domain

Prerequisites

• A running Dashdot instance accessible via a domain or IP
• HTTPS configured (e.g., https://dash.example.com) via reverse proxy
• A free account at vigilmon.online

Step 1: Verify Dashdot Web UI Availability

Dashdot serves its React-based dashboard from the root path. A healthy instance returns HTTP 200 with the web application HTML:

curl -I https://dash.example.com
# Expected: HTTP/2 200

The root response includes Dashdot's JavaScript bundle. A 502 Bad Gateway or connection refused means the Dashdot container is down or the reverse proxy is misconfigured.

Step 2: Create a Vigilmon HTTP Monitor for Web Availability

1. Log in to Vigilmon → Add Monitor → HTTP.
2. URL: https://dash.example.com.
3. Check interval: 60 seconds.
4. Response timeout: 10 seconds.
5. Expected status: 200.
6. Keyword: dashdot (or Dashdot).
7. Label: Dashdot Web UI.
8. Click Save.

This monitor catches:

• Dashdot Docker container crashes or restarts
• Reverse proxy configuration errors blocking traffic to the container
• Out-of-memory kills when the host is under heavy load
• Network interface or port conflicts preventing Dashdot from binding

When this monitor fires, you lose real-time visibility into your server's resource usage — CPU, memory, disk, and network graphs go dark.

Step 3: Monitor the Dashdot API Health Endpoint

Dashdot exposes an internal REST API that serves live metrics to its frontend. The /api/info endpoint returns JSON with the system's configuration and version information:

curl https://dash.example.com/api/info
# Expected: HTTP 200 with JSON body

A typical response:

{"os":{"distro":"Ubuntu","release":"22.04"},"cpu":{"brand":"Intel Core i5"},"ram":{"size":16384}}

This endpoint is particularly useful because it confirms the Node.js backend is alive and collecting data, not just that a static file is being served.

1. Add Monitor → HTTP.
2. URL: https://dash.example.com/api/info.
3. Check interval: 2 minutes.
4. Expected status: 200.
5. Keyword: os.
6. Label: Dashdot API Health.
7. Click Save.

Why monitor the API separately? A reverse proxy can serve a cached or static error page with HTTP 200 while the Dashdot backend is down. The API endpoint confirms the application's data collection layer is actually running, not just the web server.

Step 4: Track Response Time for Performance Degradation

Dashdot is a real-time dashboard — it refreshes metrics on a tight polling interval. Slow response times from the API cause laggy charts and delayed readings, which defeats the purpose of a live monitoring dashboard.

Vigilmon records response time for every check. To set up response time alerting:

1. Open the Dashdot Web UI monitor you created in Step 2.
2. Navigate to Advanced → Response Time Threshold.
3. Alert if response time exceeds: 3000 ms.
4. Click Save.

Common causes of Dashdot response time degradation:

• Host CPU or I/O saturation (the very condition Dashdot is supposed to show you)
• Disk I/O pressure slowing /proc reads on Linux hosts
• Reverse proxy buffering or connection pool exhaustion
• Container resource limits constraining the Dashdot process

A Dashdot that's slow to respond is often a leading indicator that the host itself is under load — the monitoring tool becomes its own diagnostic signal.

Step 5: Monitor SSL Certificates

Dashdot is typically accessed at a custom subdomain (dash.example.com). An expired SSL certificate locks you out of your dashboard and forces you to either accept a browser security warning or edit your TLS configuration while your host may already be struggling.

1. Add Monitor → SSL Certificate.
2. Domain: dash.example.com.
3. Alert when expiry is within: 30 days.
4. Alert again: 14 days, 7 days, 3 days, 1 day.
5. Click Save.

Step 6: Configure Alerting

In Vigilmon under Settings → Notifications, configure your alert channels:

| Monitor | Trigger | Action | |---|---|---| | Web UI | Non-200 or keyword missing | Check Dashdot container status; inspect Docker logs | | API Health | Non-200 or keyword missing | Check Node.js backend; restart container if needed | | Response Time | > 3 s | Investigate host CPU/IO; check container resource limits | | SSL Certificate | < 30 days to expiry | Renew certificate; verify Let's Encrypt auto-renewal |

Alert after: 2 consecutive failures for HTTP monitors. Transient spikes during metric collection are normal — two consecutive failures confirm a real issue.

Common Dashdot Failure Modes and What Vigilmon Catches

| Scenario | Vigilmon monitor | |---|---| | Dashdot container crash | Web UI and API monitors fire simultaneously | | Reverse proxy misconfiguration | Web UI monitor fires; container may be healthy | | Host OOM kill affecting Dashdot | API monitor fires; web UI may serve stale cached response | | /proc filesystem permission error | API returns errors; keyword check fails | | SSL certificate expires | SSL monitor alerts at 30 days | | Response time > 3 s | Response time threshold alert fires | | DNS misconfiguration | All monitors fire simultaneously | | Port conflict on container restart | Web UI monitor fires after next check |

Your system dashboard should be the most reliable thing on your server — the tool you reach for the moment something else acts up. Vigilmon watches Dashdot's web interface, API health, response time, and SSL certificate so you know the moment your visibility layer goes dark.

Start monitoring Dashdot in under 5 minutes — register free at vigilmon.online.