Website Monitoring

Central Logging can monitor your websites and web services for uptime, performance, and content changes. The scheduler wakes every minute and runs whichever monitors are due, and alerts are sent through your configured notification channel.

For a worked setup, see monitoring website uptime from your own server.

Setting Up a Monitor

From the Website Monitors page, create a new monitor with a Name and a URL. The remaining settings are on the monitor’s edit page:

• Check Frequency — Every 1, 2, 5 or 10 minutes
• Keyword — Optional text to search for in the response body
• Alert When — If a keyword is set, choose to alert when the keyword exists or does not exist in the response
• Case Sensitive — Whether keyword matching is case-sensitive (default: case-insensitive)

Each check is a GET request and times out after 5 seconds. Other methods, custom headers and authentication are not supported.

What Gets Checked

Each check records:

• Response Time — How long the request took (displayed in human-readable format, e.g. 24ms, 2s)
• Status Code — The HTTP response status code
• Remote IP — The resolved IP address of the target
• Response Headers — HTTP response headers
• TLS Certificate — Issuer and expiration date (for HTTPS URLs)
• Keyword Found — Whether the keyword was found in the response
• Errors — Any connection errors

Alerts

Website monitoring generates alerts for the following conditions:

• Connection Errors — When a check fails to connect — DNS failure, refused connection, timeout, TLS handshake failure. A recovery alert is sent when the site comes back up.
• Keyword State Changes — When the keyword presence changes (found vs. not found), based on your alert condition.
• TLS Certificate Expiration — An alert is sent when a TLS certificate is expiring within 7 days. This alert is throttled to once every 24 hours.

HTTP status codes do not alert. A server answering 500 or 404 has answered, so the check records the status code and nothing fires. To catch a broken page, set a keyword that appears on a healthy response and alert when it does not exist.

Error, recovery and keyword alerts fire on a change of state, and repeats within 10 minutes are suppressed so two checks landing together only notify once.

Monitor Details

The monitor detail page shows:

• Response time history
• TLS certificate expiration date
• Check frequency
• Favicon for the monitored site
• Individual check logs with full details

Check history is kept for 30 days.