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5-Minute Recipe: Log Alerting and Anomaly Detection

Until software becomes so sophisticated that it becomes truly self-healing without human intervention it will remain important that we humans be notified of any problems with computing systems we run. This is especially true for large or distributed systems where it quickly becomes impossible to watch logs manually, and a log management solution is crucial.

A common practice is to watch performance metrics instead, centralize logs, and dig into logs only when performance problems are detected. If you use Sematext Infrastructure Monitoring already, you are used to defining alerts on critical metrics, and if you are a Logsene user you can now use alerting on logs, too!

Here is how:

  1. Run your query in Logsene to search for relevant logs and press the “Save” button (see screenshot below)
  2. Mark the checkbox “Create Alert Query” and pick whether you want threshold-based or anomaly detection-based alerting:
Threshold-based alert in Logsene
Threshold-based alert in Logsene
Anomaly Detection using “Algolerts” in Logsene
Manage Alert Queries in Logsene

While alert creation dialog currently shows only email as a possible destination for alert notifications, you can actually have alert notifications sent to one or more other destinations.  To configure that go to “App Settings” as shown below:


Once there, under “Notification Transport” you will see all available alert destinations:


In addition to email, PagerDuty, and Nagios, you can have alert notifications go to any WebHook you configure, including Slack and Hipchat.

How does one decide between Threshold-based and Anomaly Detection-based Alerts (aka Algolerts)?

The quick answers:

  • If you have a clear idea about how many logs should be matching a given Alert Query, then simply use threshold-based Alerts.
  • If you do not have a sense of how many matches a given Alert Query matches on a regular basis, but you want to watch out for sudden changes in volume, whether dips or spikes, use Algolerts (Anomaly Detection-based Alerts).

For more detailed explanations of Logsene alerts, see the FAQ on our Wiki.

3-Part Blog Series about Log Queries

Speaking of log queries…this post is part of our 3-part blog series to detail the different types of Queries that Logsene lets you create.  Check out the other posts about Saved Queries and Scheduled Queries.

Keep an eye on anomalies or other patterns in your logs

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