Alert

An alert is a set of consecutive named queries calculated on a regular basis.

A set of queries is calculated once a minute. The resulting query value specified in the settings is compared to the preset threshold values.

If the result of the query specified in the settings reaches the preset threshold value, Monitoring changes the alert status to Alarm or Warning and notifies the user via a notification channel.

Alert statusesAlert statuses

An alert can have one of the following statuses:

Status	Description
OK	The metric value is within the specified normal threshold.
Warning	The metric value has reached the Warning threshold.
Alarm	The metric value has reached the Alarm critical status threshold.
No data	Lack of metric data to calculate the alert function.
Error	The alert value cannot be calculated.

Alert evaluation historyAlert evaluation history

Alert evaluation history is represented as a chart that consists of columns colored depending on the alert status as of its calculation.

To navigate through history, you can choose one of the preset output scales:

• 1h: One hour
• 1d: One day
• 1w: One week
• 1m: One month

The minimum history output scale is 1h: each column in a chart shows the alert status for the respective minute. For big output scales, the column color is made up of the statuses calculated within the interval.

By clicking a column, you bring up the alert settings information as of the selected evaluation point.

Alert settingsAlert settings

Alert settings are configured when creating an alert. You can edit them after you save the alert.

QueriesQueries

This is a set of queries that return a line or multiple lines.

You can:

• Disable query calculation by clicking or selecting Deactivate. Links to queries that are not calculated will return errors.
• Hide query calculation results on the chart by clicking .
• Present query calculation results on the chart by clicking .

Alert triggersAlert triggers

Test queryTest query

Name of query to whose calculation result an aggregation function applies.

Aggregation functionAggregation function

Aggregation function is applied to the test query calculation results.

Aggregation function	Description
At least one value	At least one metric value in the query exceeds the thresholds set in the specified period.
All values	All metric values in the query exceed the thresholds set in the specified period.
Average	Calculates an average value for each metric in the specified period. For example, if a query returns two metrics, Monitoring calculates an average value for each of them in the specified window.
Count	Calculates the number of metric values in the specified period.
Last value	Uses the latest metric value in the specified period. If Yandex Monitoring could not obtain the metric value, it changes the alert status to No data.
Maximum	Uses the maximum metric value in the specified period.
Minimum	Uses the minimum metric value in the specified period.
Sum	Calculates the sum of values for each metric in the specified period.

For example, to track the latest metric value within the last 15 minutes, select the Last function and set the evaluation window to 15m.

Comparison functionComparison function

Comparison functions are applied to aggregation function calculation results and the Warning and Alarm threshold values. If an aggregated value matches the threshold one, Monitoring changes the alert status.

WarningWarning

Threshold value upon which the alert status changes to Warning.

AlarmAlarm

Threshold value upon which the alert status changes to Alarm.

Evaluation windowEvaluation window

Time interval for which the aggregation function is calculated. The window allows to exclude sudden changes in metric values by only responding to changes over a longer period.

You can select a preset value or specify your own in the following format:

• 1h: One hour
• 1m: One minute
• 1s: One second

For example, the value 3m 45s sets an evaluation window of 3 minutes 45 seconds.

Evaluation delayEvaluation delay

Back-shift of the time window in seconds. The default value is 0. Allows avoiding a situation when an alert is triggered unexpectedly, if a query uses metrics collected at a different interval. You can select a preset value or specify your own, same as for the evaluation window.

No data processingNo data processing

Policies define the status an alert will get if there are no points in the evaluation window or no metrics matching the specified selector. Policies apply before calculating the alert trigger conditions and, depending on the result, the alert gets the status specified in the settings.