Dozzle Monitoring with Vigilmon: Uptime, Health Checks & Log Viewer Alerts

You won't know your Docker log viewer is down until you urgently need to debug a failing container. Dozzle — the lightweight, real-time Docker log viewer — is a critical ops tool. When it goes offline, you lose visibility into every container on your host. That's a terrible time to discover your monitoring tool isn't being monitored.

Vigilmon provides external uptime monitoring that catches Dozzle failures before your next incident — watching the health API, web UI availability, response time, and SSL certificate. This tutorial walks you through complete Dozzle monitoring with Vigilmon.

What You'll Build

A Vigilmon HTTP monitor on Dozzle's /healthcheck endpoint
A web UI availability monitor with keyword verification
Response time monitoring with baseline alerts
SSL certificate expiry alerts
Alert channels for immediate notification

Prerequisites

A running Dozzle instance (typically on port 8080, behind a reverse proxy)
A free account at vigilmon.online

Step 1: Monitor the /healthcheck Endpoint

Dozzle exposes a dedicated health endpoint at /healthcheck. It returns OK with a 200 status code when the service is operational and the Docker socket is accessible.

Test it from your terminal:

curl https://dozzle.yourdomain.com/healthcheck

Expected response:

OK

This endpoint confirms that the Dozzle process is running and can communicate with the Docker socket at /var/run/docker.sock. If the Docker daemon restarts, the socket becomes temporarily unavailable, or Dozzle itself crashes, this check fails immediately.

Set up the Vigilmon monitor:

Log in to Vigilmon and click New Monitor → HTTP.
Set URL to https://dozzle.yourdomain.com/healthcheck.
Set Check interval to 60 seconds.
Set Expected status code to 200.
Under Advanced → Keyword check, add:
- Keyword present: OK
Save the monitor.

Vigilmon now polls your Dozzle health endpoint every minute from multiple geographic regions.

Step 2: Monitor Web UI Availability

The /healthcheck endpoint confirms the Dozzle process is alive and the Docker socket is reachable, but doesn't verify the web interface is rendering correctly. A misconfigured reverse proxy header, a broken static asset, or a JavaScript error can leave the backend healthy while the UI is unusable.

Add a keyword monitor on the web UI:

Click New Monitor → HTTP in Vigilmon.
Set URL to https://dozzle.yourdomain.com/ (your Dozzle homepage).
Set Expected status code to 200.
Under Advanced → Keyword check, configure:
- Keyword present: Dozzle
Save.

The Dozzle homepage HTML includes the application name in its title tag and navigation. If the static file server is misconfigured or the frontend bundle is missing, this check catches the failure independently of the /healthcheck monitor.

Step 3: Response Time Monitoring

Dozzle streams Docker logs in real time via server-sent events. High response times on the main UI indicate either host resource pressure (CPU, memory) or a slow Docker socket — both conditions that degrade your log viewing experience before causing outright failure.

Configure response time alerting in Vigilmon:

Open your Dozzle web UI monitor.
Go to Settings → Response Time.
Set Alert threshold to 3000 ms (3 seconds).
Enable Alert if response time exceeds threshold for 2 consecutive checks.
Save.

This catches early performance degradation — typically the first sign of host resource exhaustion or Docker daemon slowness — well before Dozzle becomes fully unreachable.

Step 4: SSL Certificate Monitoring

Dozzle is typically served over HTTPS via Nginx, Caddy, or Traefik. An expired TLS certificate locks you out of your log viewer at exactly the wrong moment — during an incident when you most need it.

Vigilmon automatically monitors SSL certificate validity on HTTPS monitors. Configure dedicated expiry alerts:

Open any of your HTTPS Dozzle monitors in Vigilmon.
Go to Settings → SSL.
Enable Alert when certificate expires within 14 days.
Optionally enable Alert when certificate expires within 30 days for early warning.

You'll receive alerts like:

⚠️  SSL Warning: dozzle.yourdomain.com
Certificate expires in 9 days (2026-07-15)

Let's Encrypt certificates renewed by Certbot or Caddy expire silently when auto-renewal fails. Vigilmon's certificate monitor catches this gap before you're locked out.

Step 5: Alert Channels

Go to Notifications → New Channel in Vigilmon and configure your preferred alert delivery:

Email — immediate alerts to your inbox
Webhook — forward to Discord, Slack, or ntfy.sh for push notifications on mobile

For Discord, paste your server webhook URL. A Dozzle downtime alert looks like:

🔴 DOWN: dozzle.yourdomain.com/healthcheck (HTTP 502)
Dozzle health check failed
Region: EU-West
Triggered: 2026-01-15 03:22 UTC

Recovery notification:

✅ RECOVERED: dozzle.yourdomain.com/healthcheck
Downtime: 4 minutes

Step 6: Status Page

Go to Status Pages → New Status Page in Vigilmon. Add your Dozzle monitors and publish. Share the link with your ops team so they can quickly check whether Dozzle is up or whether they need an alternative approach to accessing container logs.

What You've Built

| Scenario | How Vigilmon catches it | |---|---| | Dozzle process crash or OOM kill | /healthcheck returns non-200 or connection refused | | Docker socket unavailable | /healthcheck fails (socket required for health pass) | | Reverse proxy (Nginx/Caddy) misconfiguration | HTTPS monitor detects 502 or TLS error | | Web UI assets missing or broken | Keyword monitor on homepage fails | | High host resource usage slowing log delivery | Response time threshold alert fires | | SSL certificate expired or expiring | SSL expiry alert triggers at threshold |

Your Docker log viewer is a critical ops tool — you need it most during incidents. Vigilmon watches Dozzle from outside your network, from multiple regions, with no agents to install.

Start monitoring Dozzle today — register free at vigilmon.online.