tutorial

Plex Media Server Monitoring with Vigilmon: Uptime, Health Checks & SSL Alerts

Monitor your self-hosted Plex Media Server with Vigilmon — track the /identity health check, web UI availability, transcoder service, SSL certificate expiry, and media library availability.

Plex goes down at the worst times — during a weekend binge, when guests want to watch something, or at 2 AM when an automatic update breaks the transcoder. When Plex is self-hosted, you are the support team. Without external monitoring, you're also the last person to know it's down.

Vigilmon provides external uptime monitoring for self-hosted Plex Media Server — watching your health endpoints, web interface, transcoder, SSL certificate, and media library from outside your network, without requiring any agents or plugins installed on the Plex host.

What You'll Build

  • An HTTP monitor on Plex's /identity endpoint for baseline health
  • A web UI availability check with keyword verification
  • A transcoder and media library availability check via the API
  • SSL certificate expiry alerts
  • Alert notifications so you know before your users do

Prerequisites

  • A running Plex Media Server instance (typically on port 32400 behind a reverse proxy)
  • A free account at vigilmon.online

Step 1: Monitor the /identity Endpoint

Plex exposes an unauthenticated /identity endpoint that confirms the server is running and reachable. It returns XML with the server's machine identifier and version:

curl https://plex.yourdomain.com/identity

Expected response:

<MediaContainer size="0" machineIdentifier="abc123..." version="1.40.x" />

This endpoint works without a Plex authentication token, making it the ideal lightweight health check. A Plex process crash, OOM kill, or hung startup will cause this endpoint to return a connection error.

Set up the Vigilmon monitor:

  1. Log in to Vigilmon and click New Monitor → HTTP.
  2. Set URL to https://plex.yourdomain.com/identity.
  3. Set Check interval to 60 seconds.
  4. Set Expected status code to 200.
  5. Under Advanced → Keyword check:
    • Keyword present: machineIdentifier
  6. Save the monitor.

Step 2: Monitor Web UI Availability

The Plex Web interface is a separate application from the media server backend. A broken JavaScript bundle, a missing static asset, or a misconfigured proxy can leave the backend returning 200 while every browser client sees a blank screen.

Add a keyword check on the Plex Web client:

  1. Click New Monitor → HTTP in Vigilmon.
  2. Set URL to https://plex.yourdomain.com/web/index.html.
  3. Set Expected status code to 200.
  4. Under Advanced → Keyword check:
    • Keyword present: Plex
  5. Save.

If Plex Web assets are missing or the static file routing breaks after an update, this check fires independently of the /identity monitor.

Step 3: Monitor the Transcoder and Media Library

Plex's transcoding pipeline converts media to compatible formats on the fly. A failed FFmpeg dependency, missing codec, or hardware transcoding driver issue can break playback silently — the server reports healthy while streams fail or buffer indefinitely.

Verify the transcoder and library availability using the Plex API:

Get your Plex token:

  1. Sign in to Plex Web, open any media item, click the three-dot menu → Get Info → View XML.
  2. Copy the X-Plex-Token value from the URL.

Alternatively, retrieve it from ~/.config/plex/Plex Media Server/Preferences.xml on Linux, or from the Plex log directory on Windows/Mac.

Set up the monitor:

  1. Click New Monitor → HTTP in Vigilmon.
  2. Set URL to: 
    https://plex.yourdomain.com/library/sections?X-Plex-Token=YOUR_TOKEN
  3. Set Expected status code to 200.
  4. Under Advanced → Keyword check:
    • Keyword present: MediaContainer
  5. Save.

This verifies that the media library is accessible and the Plex database is responding. A corrupted library database or a disconnected storage volume will cause this check to fail while the /identity endpoint may still return 200.

Step 4: SSL Certificate Monitoring

Plex clients — the Plex app on Roku, Apple TV, Fire Stick, Android TV, and iOS — are strict about TLS certificate validity. An expired certificate causes every remote client to fail with a TLS error, even if the server itself is running fine.

Vigilmon checks SSL certificate expiry automatically for HTTPS monitors. Enable explicit expiry alerts:

  1. Open any of your HTTPS Plex monitors in Vigilmon.
  2. Navigate to Settings → SSL.
  3. Enable Alert when certificate expires within 14 days.
  4. Optionally enable 30-day early warning for extra runway.

A typical expiry alert from Vigilmon:

⚠️  SSL Warning: plex.yourdomain.com
Certificate expires in 8 days (2026-07-08)
Action required: renew Let's Encrypt certificate

For Plex servers using Plex's built-in relay or direct HTTPS (not a reverse proxy), check that your custom domain certificate is covered by the renewal process — Plex's built-in certificate management operates separately from your system's Let's Encrypt setup.

Step 5: Configure Alert Channels

Go to Notifications → New Channel in Vigilmon and configure your alerts:

  • Email — reliable delivery for non-urgent alerts and daily summaries
  • Webhook → Discord — instant notifications to your Plex management channel
  • Webhook → Slack — for team or family group notifications

An example Discord alert when Plex goes down:

🔴 DOWN: plex.yourdomain.com/identity
Plex Media Server unreachable
Status code: Connection timeout
Region: US-East
Started: 2026-01-20 21:05 UTC

Configure escalation policies so that a brief hiccup (under 2 minutes) sends only an email, while a sustained outage triggers a Discord ping.

Step 6: Create a Status Page

Go to Status Pages → New Status Page in Vigilmon. Add all your Plex monitors, name the page (e.g. "Plex Media Server"), and publish it. Share the link with household members or co-users — it answers "is Plex down?" without requiring you to diagnose anything.

What You've Built

| Failure scenario | How Vigilmon catches it | |---|---| | Plex process crash or OOM kill | /identity returns connection error | | Reverse proxy down or misconfigured | HTTPS monitor detects 502 or TLS error | | Plex Web UI assets broken after update | Keyword check on /web/index.html fails | | Media library database corrupted | Library sections API monitor fires | | SSL certificate expired | SSL expiry alert fires at configured threshold | | Storage volume disconnected | Library sections check returns unexpected response |

Running Plex yourself gives you control over your media library without subscriptions or cloud dependency — but it also means you're responsible for keeping it online. Vigilmon watches your Plex server from the outside, from multiple regions, with no agents to install.

Start monitoring your Plex server today — register free at vigilmon.online.

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