Alert

An alert is a sequence of named queries calculated once a minute. The resulting query value is compared to the preset threshold values. If a threshold is reached, 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: 1 hour
• 1d: 1 day
• 1w: 1 week
• 1m: 1 month

The minimum scale is 1h. Each chart column shows the alert status for the given 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

QueriesQueries

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

You can:

• Disable query calculation by clicking and selecting Deactivate. Links to queries that are not calculated will return errors.
• Hide query calculation results from the chart by clicking .
• Display 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: 1 hour
• 1m: 1 minute
• 1s: 1 second

For example, 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 policyNo data policy

No data policies define how the service responds when no data points or metrics are available in the evaluation window. Data points may be missing due to delays in data collection or for other reasons. These policies apply before calculating the trigger conditions and set the alert to the appropriate status.

Available policy options:

• Manual: Policy for manual no data handling. If historical data is available, the chart will be displayed even if the evaluation window contains no data. You can use this policy to view the current values for an in-depth analysis.

• Ok, Warn, Alarm, No data: If data for at least one metric is missing in the evaluation window, each of these policies automatically sets the alert to the appropriate status. Historical data is ignored. When there is no data in the evaluation window, the chart will no longer be displayed.

  Changing the evaluation window size may affect the availability of data points and the chart display.

When there are no metrics or points in an evaluation window, you can handle this scenario in two ways:

• Change the alert status using the No metrics by selector or No points in evaluation window policies.
• Handle it manually.

No selector metricsNo selector metrics

The policy determines the alert status if no metrics were found for at least one selector. For example, these metrics do not exist or they were deleted after their TTL expired.

The possible values are:

• Default: No data for all alert types.
• OK: Changes the alert status to OK.
• Warn: Changes the alert status to Warning.
• Alarm: Changes the alert status to Alarm.
• No data: Changes the alert status to No data.

No points in evaluation windowNo points in evaluation window

The policy determines the alert status if at least one of the metrics in the evaluation window has no points.

For threshold alerts that monitor several metrics, predicates are checked for each metric independently. The final alert status is an aggregation of statuses for each of the metrics in the following order: No data < OK < Warning < Error < Alarm. If there is a line that has no points, and the No points in evaluation window policy changes the status of a threshold alert to Warning, while for another line, the predicate that changes the alert to Alarm is true, the resulting alert status will be Alarm.

The possible values are:

• Default: Default value (No data) for all types of threshold alerts.
• OK: Changes the alert status to OK.
• Warning: Changes the alert status to Warning.
• Alarm: Changes the alert status to Alarm.
• No data: Changes the alert status to No data.
• Manual: Gives control to the predicates or alert program for manual handling.

Manual processing of no dataManual processing of no data

Setting the Manual value for any policy will give control to the alert predicates or program.

Avoid the Manual value as it complicates the alert program. The No data policy value should cover most cases.