Health Checks

The Seq.Input.HealthCheck app periodically GETs an HTTP or HTTPS URL and logs various response metrics to Seq. This can form a basis for simple alerting, trend analysis, and diagnostics.

Seq.Input.HealthCheck is a Seq App that needs to be installed and configured before it can be used.

The app is installed once, and then an instance of the app is configured for each URL that needs to be health-checked.

Installing the Input

In Settings > Apps, select Install from NuGet:

The input's package id is Seq.Input.HealthCheck:

Once the app is installed, it will be shown in the app list:

Checking a URL

The app will periodically issue an HTTP GET request to a specified URL. A new instance of the app needs to be run for each URL that will be checked.

Still in the apps screen, select Add Instance next to the input app's name. This will request a number of details including the URL and checking interval.

Note that health check events take up space on the Seq server. The default checking interval of 60 seconds is recommended for most health checks.

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If the URL is an HTTPS URL, then the Seq server must trust the SSL certificate that the target server is using.

Once the instance of the app is saved, it will show in the apps list under the Health Check Input.

Use the Add Instance button to check more URLs.

Health Check Events

Each time a check is completed, details of the response will be written back to the Seq event stream:

The events include various properties describing the response.

If a health check fails, the event's level will be set to Error:

Network failures like the one above will display a StatusCode of null, since no HTTP request could be completed. If the request is completed but the status code does not indicate success, this will be included in the event, too.

Further reading

• The next step after configuring health checks is often to configure alerts based on unexpected, failed or slow responses.
• For information on integrating with ASP.NET Core health checks, see ;this article](https://blog.datalust.co/simple-health-checks-for-any-url/).
• Seq.Input.CertificateCheck is a similar input that checks SSL certificate validity and time-to-expiry, written by Jan-Pieter Zoutewelle.