Alerting: No Data in Classic Conditions are confusing and do not behave as expected

[grobinson-grafana]

Background:

Classic Conditions is a feature in Grafana Alerting that supports the reduction and comparison of one or more conditions, and the grouping of related conditions is known as a ConditionsCmd. A condition in ConditionsCmd can reduce a time series, contain an instant metric, or the result of another expression; and checks if it exceeds a threshold, falls within a range, or does not contain a value.

If a ConditionsCmd contains more than one condition, it reduces the boolean outcomes of the threshold, range or value checks using the logical operator of the right hand side condition until all conditions have been reduced to a single boolean outcome. ConditionsCmd does not follow operator precedence.

For example if we have the following classic condition:

min(A) > 5 OR max(B) < 10 AND C = 1

which reduces to the following boolean outcomes:

false OR true AND true

then the outcome of this ConditionsCmd is true.

What happened:

No Data in Classic Conditions are confusing and do not behave as expected.

• A condition in a ConditionsCmd is considered No Data when all of the series contain No Data

• The outcome of the ConditionsCmd is No Data when either:

  1. All conditions in ConditionsCmd are No Data if the and operator is used for all conditions
  2. At least one condition in ConditionsCmd is No Data if the or operator is used for all conditions
  3. The last condition in ConditionsCmd is No Data

What you expected to happen:

• A condition in a ConditionsCmd should still be considered No Data when all of the series contain No Data

• However, the outcome of the ConditionsCmd should change to the following:

  1. No Data when all the conditions are No Data
  2. No Data when at least one condition is No Data and the and operator is used

If we take the example min(A) > 5 OR max(B) < 10 AND C = 1 and create a No Data matrix:

A	B	C	Outcome
Data	No Data	No Data	No Data
Data	Data	No Data	No Data
Data	Data	Data	Data
No Data	No Data	No Data	No Data
No Data	Data	No Data	No Data
No Data	Data	Data	Data

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

Environment:

• Grafana version:
• Data source type & version:
• OS Grafana is installed on:
• User OS & Browser:
• Grafana plugins:
• Others:

[un000]

Have the same problem with a Classic conditions and multiple time series:

• series A returns numbers (5, 5, 5, 5...)
• series B returns No Data

Classic conditions:

• WHEN median() of A IS ABOVE 1 < must be fired
• OR
• WHEN median() OF B IS ABOVE 0 < No Data

Result is 0 firing, 1 normal, but firing on A expected.

[segfaultdoc]

Experiencing the same issues as the ones mentioned here. This has led us to duplicate alerts across our different environments so that they can individually trigger NoData conditions.

[esemeniuc]

Also experiencing this, would like to have this resolved

[esemeniuc]

This also seems to happen when using math expression, we're missing the NoData alert:

Alert configuration:

Results:

[JinXiu2023]

Experiencing the same probelms. The result of classic condition follows the nodata querys. It is very confusing. Will the issue be solved? Thanks very much.

[kshnyakin]

I join the request to solve the problem. It's already a year old and it's pretty serious.
The same problem and with Math conditions (a year has passed since the task was opened :-))

[Aboitier]

Also joining.

I have 3 time-series queries that are all reduced to have a single number. One of the three queries displays 'No Data' and the resulting Math Expression ($Q1+$Q2+$Q3) displays 'No Data'. I find this... strange logic.